Category: Astronomy

Charles Messier was born on June 26, 1730 in Lorraine, France. In 1744 at age fourteen, he saw the “Great Comet” appear in the skies above Lorraine and four years later in 1748, witnessed an annular solar eclipse. Perhaps it was these inspiring events that led Charles to a lifelong love of astronomy. In 1751, his excellence in handwriting brought him a job as assistant to Navy Astronomer, Joseph Delisle at the Paris Observatory. It was there that Messier learned to keep accurate records of astronomical observations and the first known entry made by Messier was the transit of Mercury across the Sun in 1753.

At the time, discovering a comet made an astronomer not only noteworthy in the eyes of their peers, but quite famous as well. In 1757 the big search was on for the Comet Halley – predicted to return during that year. While Charles wasn’t the first to locate it, he quickly came to realize during his “sweeps” that there were many objects which could be mistaken as cometary – yet remained in fixed positions. Thus began the Messier Catalog, and its first entry in 1758 was M1, the “Crab Nebula”. While Messier was compiling his catalog of non-cometary objects, he also discovered a genuine comet in 1763 and two more in 1764.

Charles’ catalog was published in several editions as it was amended and the first 45 entries was printed in 1771. In its classic form, it contained 103 entries. In later years, after careful study of his notes, Dr. Helen Sawyer Hogg and Dr. Owen Gingerich would suggest that another four to six objects should be added to bring the total to 110 – the Messier Catalog we know today. Not all of the objects were his original discovery – a fact which he made clear in his notes – and it is rather ironic that what Messier thought of to be “nuisance nebula” that might confuse the comet hunter would later become his major claim to fame. With his small telescopes aimed towards the night sky, he would give future generations of astronomers one of the finest sets of targets for mid-northern latitudes to enjoy.

It isn’t long before the novice astronomer becomes aware of the “Messier List” – and rightly so. This wonderful collection of deep sky gems are easily accessible to a small telescope and most can even be perceived in binoculars. A large majority of the objects can be conquered easily with modest instruments under less than perfect sky conditions, a few can be seen with the unaided eye and some are quite challenging. As a whole, they make for great nights of study, piquing both interest and intellect, as well as observing skills. They range from vague misty patches to grand swaths of stellar landscape!

The Messier Objects (as presented here), contain proper sky coordinates for setting circles or entry into GoTo systems. You’ll also find included a rough map of location, descriptions, scientific information and history. Do not be disappointed if your observations don’t match the grand photos that accompany each article. It is unfortunate that photography can’t always depict what can be seen at the eyepiece, but do rejoice that you are catching a smudge that’s such a huge distance away! Do not give up if you don’t find a particular object easily… Conquering the Messier list takes time and patience. There are also many fine organizations that offer awards for observing the Messier List and instructions for participation can be easily found on the web. Most of all? Enjoy your observations!

Charles Messier (archival image), Messier Objects Poster courtesy of SEDS.

Object Name: Messier 110
Alternative Designations: M110, NGC 205
Object Type: E6p Elliptical Galaxy
Constellation: Andromeda
Right Ascension: 00 : 40.4 (h:m)
Declination: +41 : 41 (deg:m)
Distance: 2900 (kly)
Visual Brightness: 8.5 (mag)
Apparent Dimension: 17×10 (arc min)

Locating Messier 110: M110 is easily located with smaller telescopes as the northeastern companion galaxy of M31 – the Great Andromeda Galaxy. It can be spotted as a small hazy patch in larger binoculars from a dark sky site and easily begins to display structure with a mid-sized telescope. While it isn’t as grand as its nearby neighbor, most backyard astronomers would find this bright little galaxy far more interesting if it were on its own! It is well suited to a small amount of light pollution and makes for an excellent suburban challenge.

What You Are Looking At: Classified as a dwarf spheroidal galaxy, M110 enjoys its life some 2.9 million years away from our solar system on the outskirts of the Andromeda Galaxy. Despite its diminuative size, its an active little galaxy with a system of 8 globular clusters in a halo around it. “We present measurements of ages, metallicities and [?/Fe] ratios for 16 globular clusters (GCs) in NGC 147, 185 and 205 and of the central regions of the diffuse galaxy light in NGC 185 and 205. Our results are based on spectra obtained with the SCORPIO multislit spectrograph at the 6-m telescope of the Russian Academy of Sciences. We include in our analysis high-quality Hubble Space Telescope/WFPC2 photometry of individual stars in the studied GCs to investigate the influence of their horizontal branch (HB) morphology on the spectroscopic analysis. All our sample GCs appear to be old (T > 8 Gyr) and metal-poor ([Z/H]??1.1) , except for the GCs Hubble V in NGC 205 (T= 1.2 ± 0.6 Gyr, [Z/H]=?0.6 ± 0.2) , Hubble VI in NGC 205 (T= 4 ± 2 Gyr, [Z/H]=?0.8 ± 0.2) and FJJVII in NGC 185 (T= 7 ± 3 Gyr, [Z/H]=?0.8 ± 0.2) . The majority of our GCs sample has solar [?/Fe] enhancement in contrast to the halo population of GCs in M31 and the Milky Way.” says M.E. Sharina (et al). “The HB morphologies for our sample GCs follow the same behaviour with metallicity as younger halo Galactic GCs. We show that it is unlikely that they bias our spectroscopic age estimates based on Balmer absorption-line indices. Spectroscopic ages and metallicities of the central regions in NGC 205 and 185 coincide with those obtained from colour–magnitude diagrams. The central field stellar populations in these galaxies have approximately the same age as their most central GCs (Hubble V in NGC 205 and FJJIII in NGC 185), but are more metal-rich than the central GCs.”

But globular clusters are old… Are there new stars forming inside of M110? “NGC 205 is a peculiar dwarf elliptical galaxy hosting in its center a population of young blue stars. Their origin is still matter of debate, the central fresh star formation activity possibly being related to dynamical interactions between NGC 205 and M31. The star formation history around the NGC 205 central nucleus is investigated in order to obtain clues to the origin of the young stellar population. Methods. Deep HST/ACS CCD photometry is compared with theoretical isochrones and luminosity functions to characterize the stellar content of the region under study and compute the recent SF rate. Our photometry reveals a previously undetected blue plume of young stars.” says L. Monaco (et al). “Our analysis suggests that (they) were produced between approximately 62 Myr and 335 Myr ago in the NGC 205 inner regions, with a latest minor episode occurring 25 Myr ago. The excellent fit of the observed luminosity function of young main sequence stars obtained with a model having a constant star formation rate argues against a tidally triggered star formation activity over the last 300 Myr. Rather, a constant SF may be consistent with NGC 205 being on its first interaction with M 31.”

Is that all? The let’s stir up the interstellar medium… “In order to understand what determines the properties of the interstellar medium (ISM) and the relation of that ISM to star formation, it is important to observe the ISM in a variety of environments unlike our solar neighborhood. One example of an environment different from the solar neighborhood is the interior of the dwarf elliptical galaxy NGC 205, a companion of M31.” says L.M. Young and K. Yo. “Though it is an elliptical, NGC 205 has long been classified as peculiar, because it has dust clouds and signs of recent star formation near its center. Therefore, given the general deficiency of gas and star formation in elliptical galaxies, NGC 205 presents an excellent opportunity to study the properties of the interstellar medium”

Having such a dominate neighbor isn’t easy, either. According to the work of K.M. Howley (et al): “NGC 205, a close satellite of the M31 galaxy, is our nearest example of a dwarf elliptical galaxy. Photometric and kinematic observations suggest NGC 205 is undergoing tidal distortion from its interaction with M31. Despite earlier attempts, the orbit and progenitor properties of NGC 205 are not well known. We perform an optimized search for these unknowns by combining a genetic algorithm with restricted N-body simulations of the interaction. Coupled with photometric and kinematic observations as constraints, this allows for an effective exploration of the parameter space. We represent NGC 205 as a static Hernquist potential with embedded massless test particles serving as tracers of surface brightness. We explore three distinct, initially stable test particle configurations: cold rotating disk, warm rotating disk, and hot, pressure-supported spheroid. Each model reproduces some, but not all, of NGC 205’s observed features, leading us to speculate that a rotating progenitor with substantial pressure support could match all of the observables.”

Did M110 form from M31, or is it just hanging on the coattails of its big brother? Let’s ask the Isaac Newton Telescope. “The initial results of this survey could not have been more surprising: despite exhibiting a near pristene disk, M31’s halo is full of substructure and points to a history of accretion and disruption. Metal-poor/young stars are coded blue whilst metal rich/older stars are coded red. This spectacular image shows in amazing detail the wealth of information that the INT is helping to reveal about the structure of this previously invisible region of galaxies. The most obvious piece of substructure visible is the giant stellar stream (visible in the south-east). This extends to near the edge of our survey —a projected distance of some 60kpc. In fact, by examining the systematic shift in the luminosity function of the stream as a function of galactocentric radius, we find its actual length is much greater than 100kpc. The similarity of the colour of this feature with the loop of material at the north of the survey suggests a connection: deep follow-up imaging using HST/ACS confirms that they possess the same stellar population. It seems likely that the northern feature is an extension of the stream, after it has passed very close to the centre of the potential of M31.” says Alan McConnachie (et al). “A second large stellar stream candidate has also been identified. The progenitor of this feature appears to be the satellite galaxy NGC 205, although this awaits spectroscopic confirmation. This object has long been known to be tidally perturbed but it is only now that the full extent of its disruption is becoming clear.”

History: M110 was discovered by Charles Messier on August 10, 1773. In his notes he writes: “I examined, under a very good sky, the beautiful nebula of the girdle of Andromeda [M31], with my achromatic refractor, which I had made to magnify 68 times, for creating a drawing like the one of that in Orion [M42] (Mem. de l’acad. 1771, pag. 460). I saw that [nebula] which C. [Citizen] Legentil discovered on October 29, 1749 [M32]. I also saw a new, fainter one, placed north of the great [nebula], which was distant from it about 35′ in right ascension and 24′ in declination. It appeared to me amazing that this faint nebula has escaped [the discovery by] the astronomers and myself, since the discovery of the great [nebula] by Simon Marius in 1612, because when observing the great [nebula], the small is located in the same field [of view] of the telescope. I will give a drawing of that remarkable nebula in the girdle of Andromeda, with the two small which accompany it.”

Caroline Herschel independently discovered M110 on August 27, 1783, little more than 10 years after Messier, and William Herschel numbered it H V.18 when he cataloged it on October 5, 1784 and placed in his notes: “.. There is a very considerable, broad, pretty faint, small nebula near it [M31]; my Sister [Caroline] discovered it August 27, 1783, with a Newtonian 2-feet sweeper. It shews the same faint colour with the great one, and is, no doubt, in the neighborhood of it. It is not [M32] ..; but this is about two-thirds of a degree north preceding it, in a line parallel to Beta and Nu Andromedae.”

M110 would later be cataloged by John Herschel and poetically observed by Admiral Smyth: “A large faintish nebula of an oval form, with its major axis extending north and south. It it between the left arm and robes of Andromeda, a little to the np [North Preceding, NW] of 31 Messier; and was discovered by Miss Herschel in 1783, with a Newtonian 2-foot [FL] sweeper. It lies between two sets of stars, consisting of four each, and each disposed like the figure 7, the preceding group being the smallest; besides other telescopic stars to the south, This mysterious apparition was registered by H [William Herschel] as 30′ long and 12′ broad, but only half that size by his son; and there was a faint suspicion of a nucleus. This doubt must stand over for the present, – for whatever was a matter of uncertainty in the 20-foot reflector, would have no chance of definition in my instrument. It was carefully differentiated with Beta Andromedae.”

Enjoy this great little galaxy!

Top M110 image credit, Palomar Observatory courtesy of Caltech, M110 courtesy of J.C. Cuillandre, CFHT, M110 Image by Lowell Observatory, M110 by Adam Block/NOAO/AURA/NSF, Messier’s Andromeda and Companion Sketch (public image) and M110 image courtesy of NOAO/AURA/NSF.

Object Name: Messier 109
Alternative Designations: M109, NGC 3992
Object Type: Sbc Barred Spiral Galaxy
Constellation: Ursa Major
Right Ascension: 11 : 57.6 (h:m)
Declination: +53 : 23 (deg:m)
Distance: 55000 (kly)
Visual Brightness: 9.8 (mag)
Apparent Dimension: 7×4 (arc min)

Locating Messier 109: Locating M109 is a snap. It’s position is less than a degree southeast of Gamma Ursae Majoris – Phecda – the inside bottom corner star of the Big Dipper asterism. But just because it is easy to find doesn’t mean it is easy to see! Although it is considered rather large, the outer spiral arms are quite faint and only the bright central bar and nucleus region show well to smaller telescopes. Messier 109 will require dark, clear skies and at least mid-sized aperture to begin seeing details.

What You Are Looking At: This member of the Ursa Major Galaxy Cloud is about 55 million light years away from Earth and running away from us at an approximate speed of 1142 kilometers per second. However, it is not alone… It has companion galaxies as well – companions that may be contributing to M109’s bright central bar. “Detailed neutral hydrogen observations have been obtained of the large barred spiral galaxy NGC 3992 and its three small companion galaxies, UGC 6923, UGC 6940, and UGC 6969. For the main galaxy, the HI distribution is regular with a low level radial extension outside the stellar disc. However, at exactly the region of the bar, there is a pronounced central H I hole in the gas distribution. Likely gas has been transported inwards by the bar and because of the emptiness of the hole no large accretion events can have happened in recent galactic times.” says R. Bottemar (et al).

“The gas kinematics is very regular and it is demonstrated that the influence of the bar potential on the velocity field is negligible. A precise and extended rotation curve has been derived showing some distinct features which can be explained by the non-exponential radial light distribution of NGC 3992. The decomposition of the rotation curve gives a slight preference for a sub maximal disc, though a range of disc contributions, up to a maximum disc situation fits nearly equally well. For such a maximum disc contribution, which might be expected in order to generate and maintain the bar, the required mass-to-light ratio is large but not exceptional.”

And indeed its spiral structure is what makes it beautiful. Says K. Wilke: “For the intermediate-type barred galaxies NGC 3992 and NGC 7479 stationary models are constructed which reproduce in a consistent manner the observed distribution of the luminous matter and the observed gas kinematics in the inner disk regions affected by the bar. We present 2D fits to the observed NIR luminosity distributions that consist of three components: a bulge, a bar, and a disk. By projection to the reference frame of the galaxy, artificial rotation curves for every model are obtained and are compared with the observed rotation curves of the HII-gas. The parameters of the NGC 3992- and NGC 7479-models are optimized by computing and evaluating a large number of models with different parameter sets. This iterative procedure results in final models that accurately reproduce the morphological structure of NGC 3992 and NGC 7479 as well as the observed kinematics of the HII-gas.”

Because Messier 109 has a slightly different structure to its arms, it makes it a great place for astronomers to discover how starforming regions evolve. According to the work of J. P. Cepa and J. E. Beckman: “The present study estimates the efficiency ratio for massive star formation between the arms and the interarm discs of three grand design spirals. The estimate is based on H mapping observations of theHii regions in the galaxies. We find that this efficiency ratio is 10 in the zones between the Lindbalad resonances and the radius which we infer to be co-rotation, dropping to values close to unity at these three resonance raddii. these results point to a dominant influence of resonance structure in stimulating star formation in grand design spirals.”

However, Messier 109 isn’t just producing new stars. It’s magnetic halo is producing ultra high energy cosmic rays! “The study of the propagation of ultra-high-energy cosmic rays (UHECRs) is a key step to unveiling the secret of their origin. Up to now only the influence of the galactic and extragalactic magnetic fields was considered. In this article we focus our analysis on the influence of the magnetic field of the galaxies standing between possible UHECR sources and us. Our main approach is to start from the well-known galaxy distribution up to 120 Mpc.” says Pascal Chardonnet and Alvise Mattei. “We use the most complete galaxy catalog: the LEDA catalog. Inside a sphere of 120 Mpc, we extract 60,130 galaxies with known positions. In our simulations we assign a halo dipole magnetic field (HDMF) to each galaxy. The code developed is able to retro-propagate a charged particle from the arrival points of UHECR data across our galaxy sample. We present simulations in the case of the Virgo Cluster and show that there is a nonnegligible deviation in the case of protons of 7 × 1019 eV, even if the B value is conservative. Then special attention is devoted to the AGASA triplet, where we find that NGC 3998 and NGC 3992 could be possible source candidates.”

But things aren’t sitting still inside Messier 109 while the action goes on. The central bar is rotating rather unusually, too. “The pattern speed is one of the fundamental parameters that determines the structure of barred galaxies. This quantity is usually derived from indirect methods or by employing model assumptions. The number of bar pattern speeds derived using the model-independent Tremaine & Weinberg technique is still very limited. We present the results of model-independent measurements of the bar pattern speed in four galaxies ranging in Hubble type from SB0 to SBbc.” says Joris Gerssen (et al). “Three of the four galaxies in our sample are consistent with bars being fast rotators. The lack of slow bars is consistent with previous observations and suggests that barred galaxies do not have centrally concentrated dark matter haloes. This contradicts simulations of cosmological structure formation and observations of the central mass concentration in nonbarred galaxies.”

When it comes to galaxy dynamics, it is this speed that determines the bulge in the center. Says E. M. Corsini: “The dynamics of a barred galaxy depends on the pattern speed of its bar. The only direct method for measuring the pattern speed of a bar is the Tremaine-Weinberg technique. This method is best suited to the analysis of the distribution and dynamics of the stellar component. Therefore it has been mostly used for early-type barred galaxies. Most of them host a classical bulge. On the other hand, a variety of indirect methods, which are based on the analysis of the distribution and dynamics of the gaseous component, has been used to measure the bar pattern speed in late-type barred galaxies. Nearly all the measured bars are as rapidly rotating as they can be. By comparing this result with high-resolution numerical simulations of bars in dark matter halos, it is possible to conclude that these bars reside in maximal disks.”

History: This interesting spiral galaxy was first turned up by Pierre Mechain on the night of March 12, 1781. It was later confirmed by Charles Messier on March 24, 1781, along with M108 while doing the computations for M97. Originally Messier included this finding as object #99 is his rough draft, but did not give it a position. From Mechain’s letter to Bernoulli of May 6, 1783: “A nebula near Beta in the Great Bear. Mr. Messier mentions, when indicating its position, two others, which I also have discovered and of which one is close to this one [M108], the other is situated close to Gamma in the Great Bear [this is M109], but I could not yet determine their positions.”

Because it wasn’t included in the catalog, Sir William Herschel independently recovered it on on April 12, 1789, gave it his own catalog number and writes: “Considerably bright. Irregularly formed. Extended meridionally [along the Meridian, i.e. North-South]. Little brighter Nucleus. With faint brances 7 or 8′ long, and 5 or 6′ broad.” His son John would also go on to add it to his catalog on February 17, 1831 when he writes: “Bright; Large; very suddenly brighter to the Middle; round; 3′ diameter. Fine object.”

Because M109 wasn’t added to the published Messier catalog of the time, poetic stargazer – Admiral Smyth – would attribute its discovery to Herschel and write in his own notes: “A large pale-white nebula, on the Bear’s right haunch, about 1d 1/4 south of Gamma; discovered in April, 1789. It has a peculiar appearance in the field, from there being a coarse small double star north of it, and from its being followed by a vertical line of five equidistant telescopic stellar attendants. This object is fine, but, in my instrument, faintish; it brightens towards the middle; and WH says there is, in that part, an unconnected star, the which I cannot make out. From every inference this nebula is a vast and remote globular cluster of worlds, for JH assures us it is actually resolvable. By its blazing towards the centre, proof is afforded that the stars are more condensed there than around its margin, an obvious indication of a clustering power directed from all parts towards the middle of the spherical group. In other words, the whole appearance affords presumptive evidence of a wonderful physical fact, — the actual existence of a central force.”

Although he didn’t know he was looking at a distant galaxy, Smyth definitely had some sort of clue as to what was going on. May your observations prove as interesting!

Top M109 image credit, Palomar Observatory courtesy of Caltech, M109 Images courtesy of SSDS, M109 courtesy of Hunter Wilson (Wikipedia), M109 IPAC Image, M109 Core Region courtesy of NASA/ESA Hubble Space Telescope, M109 2MASS Image and M109 image courtesy of NOAO/AURA/NSF.

Object Name: Messier 108
Alternative Designations: M108, NGC 3556
Object Type: Sc Spiral Galaxy
Constellation: Ursa Major
Right Ascension: 11 : 11.5 (h:m)
Declination: +55 : 40 (deg:m)
Distance: 45000 (kly)
Visual Brightness: 10.0 (mag)
Apparent Dimension: 8×1 (arc min)

Locating Messier 108: M108 is easily located about one quarter the distance between Beta Ursa Majoris and Gamma Ursa Majoris… but locating doesn’t mean it’s always easily seen! At nearly edge-on in presentation, this mottled streak of light is a rather difficult catch for smaller telescopes and requires good, dark sky to see any details. Larger instruments will make out both faint and bright patches in structure.

What You Are Looking At: Located about 45 million light years away from Earth and running away from us at 772 kilometers per second, this disturbed looking galaxy is rich in dark dust, star forming regions and a supershell. “We present the first high resolution HI maps of the nearby edge-on galaxy, M 108 (NGC 3556). This galaxy is known to have a radio continuum thick disk and we have now found HI arcs and extensions protruding from the plane on kpc scales. Two HI arcs, positioned at either end of the optical major axis have the signature of expanding shells and, in the context of energy input from supernovae and stellar winds, the required input energy for the eastern shell is > 2.6 times 10^56 erg, making this the most energetic HI supershell yet detected.” says D. L. Giguere and J. Irwin.

“Since this galaxy is isolated, the supershells are unlikely to have been created through impacting external clouds, yet the required input energy is also greater than that available from the observed internal star formation rate. Thus it would appear that some form of energy enhancement (such as magnetic fields) must also be important in creating these features. The supershells are so dominant that they distort the outer major axis. Without a knowledge of the resolved structure of these features, the galaxy would mistakenly be considered warped. We have also modeled the underlying smooth density and velocity distributions of this galaxy by reproducing the line profiles in the HI cube.”

What else is unusual about Messier 108? Try a water maser that disappeared. “NGC 3556: is a nearby spiral galaxy located at a distance of 12Mpc. Its FIR luminosity, LFIR 1010 L?, is similar to that of the Milky Way. The detected H2O maser line initially had a central velocity of 738 kms?1. With a peak flux of 20–40mJy, the maser had an isotropic luminosity of 1 L. More recently, the maser feature disappeared and another weaker component, at 708 kms?1, was detected.” says A. Tarchi (et al). “The high rate of maser detections in our sample of galaxies strongly suggests that a relationship between FIR flux density and maser phenomena exists.”

What else is hiding? Perhaps an intermediate mass black hole, you say? “We present a 60 ks Chandra ACIS-S observation of the isolated edge-on spiral galaxy NGC 3556, together with a multiwavelength analysis of various discrete X-ray sources and diffuse X-ray features. Among 33 discrete X-ray sources detected within the IB = 25 mag arcsec-2 isophote ellipse of the galaxy, we identify a candidate for the galactic nucleus, an ultraluminous X-ray source that might be an accreting intermediate-mass black hole, a possible X-ray binary with a radio counterpart, and two radio-bright giant H II regions.” says Q. Daniel Wang (et al). “The diffuse X-ray emission exhibits significant substructures, possibly representing various blown-out superbubbles or chimneys of hot gas heated in massive star-forming regions. This X-ray-emitting gas has temperatures in the range of ~(2-7) × 106 K and has a total cooling rate of ~2 × 1040 ergs s-1. The energy can be easily supplied by supernova blast waves in the galaxy. These results show NGC 3556 to be a galaxy undergoing vigorous disk-halo interaction. The halo in NGC 3556 is considerably less extended, however, than that of NGC 4631, in spite of many similarities between the two galaxies. This may be due to the fact that NGC 3556 is isolated, whereas NGC 4631 is interacting. Thus, NGC 3556 presents a more pristine environment for studying the disk-halo interaction.”

History: According to SEDS, Charles Messier’s hand-written preliminary and unpublished version of his catalog, M108, similar to M109, was discovered by Pierre Méchain shortly after M97 (which he had found February 16, 1781): Méchain discovered M108 3 days after M97 on February 19, 1781, and M109 on March 12, 1781. Both objects were apparently also observed by Charles Messier when he measured the position of M97 (March 24, 1781), but apparently he didn’t find occasion to obtain positions for these objects at that time. Messier listed this object, M108, under number “98” in his preliminary manuscript version of his catalog, without giving a position.

M108 was catalog again by William Hershel in 1789, but best described by Admiral Smyth who said: “A large milky-white nebula, on the body of the Great Bear, with a small star at its sp [South Preceding, SW] apex, and an 8th-magnitude preceding [W] it at double the distance; there is also a brightish group in the np [North Preceding, NW] quadrant. It is easily found, since it lies only about 1 deg south-east of Beta, Merak. This object was discovered by H. [William Herschel] in April, 1789; and is No. 831 of his son’s Catalogue. It is faint but well defined, being much elongated with an axis-major trending sp [South Preceding, SW] and nf [north following, NE] across the parallel, and a small star, like a nucleus, in its center. As H. [WH] considers this star to be unconnected with the nebula, it follows that it is between us and it, and therefore strengthens to confirmation our belief in the inconceivable remoteness of those mysterious bodies.”

Enjoy every inch of this mysterious body!

Top M108 image credit, Palomar Observatory courtesy of Caltech, M108 Hubble Image, M108 courtesy of Ole Nielsen (Wikipedia), M108 GALEX image and M108 image courtesy of NOAO/AURA/NSF.

Object Name: Messier 107
Alternative Designations: M107, NGC 6171
Object Type: Class X Globular Cluster
Constellation: Ophicuhus
Right Ascension: 16 : 32.5 (h:m)
Declination: -13 : 03 (deg:m)
Distance: 20.9 (kly)
Visual Brightness: 7.9 (mag)
Apparent Dimension: 13.0 (arc min)

Locating Messier 107: M107 is easily found about 4 degrees (3 fingerwidths) south/southwest of Zeta Ophiuchi. In binoculars it is a small, round contrast change and it can even be spotted in larger finderscopes from a dark sky location. At near magnitude 8, Messier 107 can take some moderate light pollution and is well suited for urban and suburban viewing. In a 4.5″ telescope, this globular cluster will take on a grainy appearance and will resolve more and more as aperture is applied.

What You Are Looking At: Enjoying its “space” some 21,000 light years away from Earth, this darkly obscured globular cluster spans 80 light years and is coming towards us at a speed of 147 kilometers per second. While that may sound fast, in astronomical terms it’s a rather weak acceleration. “As part of an ongoing program to test Newton’s law of gravity in the low acceleration regime using globular clusters, we present here new results obtained for NGC 6171. Combining VLT spectra for 107 stars with data from the literature, we were able to trace the velocity dispersion profile up to 16 pc from the cluster center, probing accelerations of gravity down to 3.5e-9 cm/s/s. The velocity dispersion is found to remain constant at large radii rather than follow the Keplerian falloff.” says Riccardo Scarpa (et al). “We have now studied three clusters and all three have been found to have a flat dispersion profile beyond the radius where their internal acceleration of gravity is ~ 1e-8 cm/s/s. Whether this indicates a failure of Newtonian dynamics or some more conventional dynamical effect (e.g., tidal heating) is still unclear. However, the similarities emerging between globular clusters and elliptical galaxies seem to favor the first of the two possibilities.”

What’s causing M107 to slow down? At home in the halo of our own galaxy, this globular cluster could be caught in our own tidal drag from the MIilky Way’s central bar. Says Christine Allen: “We study the effect of a bar in the galactic orbits of forty-five globular clusters whose absolute proper motions are known. The orbital characteristics of the orbits are compared with those obtained for the case of an axisymmetric galactic potential. Tidal radii are computed and discussed for both cases.”

But there could be other reasons as well… “We report on the detection of SiO masers in Asymptotic Giant Branch variables toward bulge/disk globular clusters. In five out of six cases, the radial velocities are compatible with the optically measured radial velocities of globular clusters in the assessed uncertainty. Two sources, toward Terzan 5 and Terzan 12, lie very close to the cluster centers. The objects toward Pal 6 and Terzan 12 have luminosities appropriate to the AGB tip in globular clusters, while those toward NGC 6171, Pal 10, and Terzan 5 are brighter than expected.” says M. Noriyuki. “It is suggested that the latter three may have evolved from merged binaries, offering a test for binary-evolution scenarios in globular clusters, if the membership is approved.”

M107 might be a middleweight contender when it comes to metallicity, but it finishes the round with 25 variable stars. It is also known to contain blue straggler stars, too… But where did they come from? With all of those suns so closely packed together, it stands to reason that a collision may have happened more than once. “There are several observed phenomena in globular clusters that are thought to be the result of dynamical processes or binary star evolution. This review examines these manifestations of the interaction between globular cluster dynamics and stellar evolution. Blue stragglers may be formed by the evolution of primordial binaries or by collisions.” says A. Knudsen. “Current evidence suggests that both processes are likely to occur, and that the observed blue straggler sequences can place dynamically interesting limits on rates. Color gradients in globular clusters are thought to becaused by the stripping of giants by collisions, although the creation of blue subdwarfs by the same process may also be required to explain the observations. The observed X-ray sources and radio pulsars are apparently also made by a variety of dynamical processes that are still not fully understood.”

History: Messier 107 was originally discovered by Pierre Mechain in April 1782 – perhaps destined for a future edition of the Messier Catalog. In his letters he writes: “In April 1782 I discovered a small nebula in the left flank of Ophiuchus between the stars Zeta and Phi, the position of which I have not yet observed any closer.” It was independently recovered again by Sir William Herschel on May 12, 1793 and listed in his unpublished notes as: “A very beautiful extremely compressed cluster of stars, extremely rich, 5 or 6′ in diameter, gradually more compressed toward the centre.”

While Herschel’s son John would later add it to his catalog, it was observed beforehand by Admiral Smyth who states in his notes: “A large but pale granulated cluster of small stars, on the Serpent-bearer’s right leg. There are five telescopic stars around it, so placed as to form a crucifix, when the cluster is high in the field; but the region immediately beyond is a comparative desert. After long gazing, this object becomes more compressed in the centre, and perplexes the mind by so wonderful an aggregation. It was discovered by WH in May, 1793, and was registered 5′ or 6′ in diameter. The mean place was obtained by differentiation with Zeta Ophiuchi, from which it is distant 3 deg to the south-south-west, in the line between Beta Scorpii and Beta Ophiuchi.”

May you enjoy gazing into it until the stars resolve!

Top M107 image credit, Palomar Observatory courtesy of Caltech, Messier 107 Hubble Image, M107 courtesy of NOAO, Messier 107 courtesy of Western Washington University, M107 2MASS image and M107 image courtesy of NOAO/AURA/NSF.

Object Name: Messier 106
Alternative Designations: M106, NGC 4258
Object Type: Sbp Spiral Galaxy
Constellation: Canes Venetici
Right Ascension: 12 : 19.0 (h:m)
Declination: +47 : 18 (deg:m)
Distance: 25000 (kly)
Visual Brightness: 8.4 (mag)
Apparent Dimension: 19×8 (arc min)

Locating Messier 106: To begin in roughly the correct area to locate M106, identify the bottom corner star (towards the handle) of the Big Dipper asterism. This is Gamma Ursa Majoris. Now, locate Alpha Canes Venetici – Cor Caroli – about a fistwidth southeast. You will know if you have the correct star because Cor Caroli is an easily split double that will reveal itself to both binoculars, finderscopes and small telescopes. Now start your hunt for M106 directly between Gamma UM and Alpha CVn. At nearly magnitude 8, M106 can be spotted in most binoculars from a dark sky site and is easily seen in all telescopes. Unlike most galaxies, it is bright enough to stand up to moderate light pollution and resolves its structure well in larger instruments.

What You Are Looking At: Located roughly 25 million light years away, M106 may be a member of a small galaxy cloud that centers around Ursa Major. It has a great spiral structure, but many hidden facets. “It has been claimed that the megamaser observations of the nucleus of NGC 4258 show that a massive black hole is present in its center. We show that the evidence of ejection of gas, radio plasma, and X-ray emitting QSOs from this nucleus all show that the ejection is coming from the center in a curving flow within a cone with angle ~40 degrees, centered at P.A. 100 degrees.” says E.M. Burbidge abd G. Burbidge of the University of California, San Deigo. “This is close to the direction in which the velocities from the megamaser have been measured, so that the evidence taken as a whole suggests that the masering gas also is being ejected in the same direction at velocities +/- 900 km/sec and not rotating about a massive black hole. Thus it does not provide evidence for a black hole in the center.”

However, not every study agrees with that. “The sub-parsec masing disk recently found to be orbiting a central mass in the Seyfert/LINER galaxy NGC~4258 provides the most compelling evidence to date for the existence of a massive black hole in the nucleus of a galaxy. The disk is oriented nearly edge-on and the X-ray spectrum is heavily absorbed. Therefore, in this galaxy, the optical emission-line spectrum generally exhibited by an active galactic nucleus is perhaps best sought using polarized light: probing for light scattered off material surrounding the central source.” says Belinda J. Wilkes (et al). “New polarimetry of NGC~4258 has uncovered a compact polarized nucleus whose spectrum consists of a faint blue continuum similar to those of unobscured quasars, plus broadened emission lines. The lines are strongly linearly polarized ($5-10$%) at a position angle coincident with the plane of the maser disk. This result provides substantiating evidence for a weakly active central engine in NGC~4258 and for the existence of obscuring, orbiting tori which impart many of the perceived distinctions between various types of active galaxy.”

And indeed the central core region – and its accompanying accretion disc continue to fascinate astronmers. “A wealth of new information about the structure of the maser disk in NGC 4258 has been obtained from a series of 18 VLBA observations spanning three years, as well as from 32 additional epochs of spectral monitoring data from 1994 to the present, acquired with the VLA, Effelsberg, and GBT. The warp of the disk has been defined precisely. The thickness of the maser disk has been measured to be 12 micro-arcseconds (FWHM), which is slightly smaller than previously quoted upper limits. Under the assumption that the masers trace the true vertical distribution of material in the disk, from the condition of hydrostatic equilibrium the sound speed is 1.5 km s?1, corresponding to a thermal temperature of 600K.” says James M. Moran (et al).

“The accelerations of the high velocity maser components have been accurately measured for many features on both the blue and red side of the spectrum. The azimuthal offsets of these masers from the midline (the line through the disk in the plane of the sky) and derived projected offsets from the midline based on the warp model correspond well with the measured offsets. This result suggests that the masers are well described as discrete clumps of masing gas, which accurately trace the Keplerian motion of the disk. However, we have continued to search for evidence of apparent motions caused by “phase effects.” This work provides the foundation for refining the estimate of the distance to NGC 4258 through measurements of feature acceleration and proper motion. The refined estimate of this distance is expected to be announced in the near future.”

But that’s not all that’s hidden. Try magnetic interaction of jets and molecular clouds in NGC 4258! “NGC 4258 is a well known spiral galaxy with a peculiar large scale jet flow detected in the radio and in H alpha. Due to the special geometry of the galaxy, the jets emerge from the nuclear region through the galactic disk – at least in the inner region. Also the distribution of molecular gas looks different from that in other spiral galaxies: 12CO(1-0) emission has only been detected in the center and along the jets and only up to distances of about 50” (1.8 kpc) from the nucleus. This concentration of CO along the jets is similar to what is expected as fuel for jet-induced star formation in more distant objects. The reason for the CO concentration along the inner jets in NGC 4258 was not understood and is the motivation for the observations presented here.” says M. Krause (et al).

“We detected two parallel CO ridges along a position angle of -25° with a total length of about 80” (2.8 kpc), separated by a CO depleted funnel with a width of about 5” (175 pc). The Halpha emission is more extended and broader than the CO emission with its maximum just in between the two CO ridges. It seems to be mixed in location and in velocity with the CO emission. In CO we see a peculiar velocity distribution in the iso-velocity map and p-v diagrams. We discuss different scenarios for an interpretation and present a model which can explain the observational results consistently. We propose here that the concentration of CO along the ridges is due to interaction of the rotating gas clouds with the jet’s magnetic field by ambipolar diffusion (ion-neutral drift). This magnetic interaction is thought to increase the time the molecular clouds reside near the jet thus leading to the quasi-static CO ridge.”

History: M106 was discovered by Pierre Mechain in July 1781. In his personal letters to Bernouli he writes: “In July 1781 I found another nebula close to the Great Bear [Ursa Major] near the star No. 3 of the Hunting Dogs [Canes Venatici] and 1 deg more south, I estimate its right ascension 181d 40′ and its northern declination about 49d. I will be going to determine the more accurate position of this one shortly.” It was later independently rediscovered by William Herschel on March 9, 1788 who pens in his notes: “Very brilliant. Bright Nucleus. With faint milky branches north preceding and south following. 15′ long and to the south following running into very faint nebulosity extending a great way. The nucleus is not round.”

Roughly a half century later it would be observed and cataloged by Admiral Smyth who said: “A large white nebula, closely following the haunches of the Greater Bear, discovered by WH [William Herschel] in 1788, and No. 1175 of his son’s Catalogue. It is a noble-sized oval, trending rather from the vertical in a direction np [north preceding, NW] and sf [south following, SE], with a brightish nucleus in its southern portion; the lateral edges are better defined than the ends. It is preceded by two stars of the 10th magnitude, and followed by two others; and there are also some minute points of light in the field, seen occasionally by glimpses. This object was carefully differentiated with Alkaid; and its place will be indicated by a running diagonal line across the square of Ursa Major, from Alpha through Gamma, and carrying it 7 1/2 deg into the south-east, that is, a little less than the distance between those stars.”

Enjoy your observations!

Top M106 image credit, Palomar Observatory courtesy of Caltech, M106 Hubble Image, M106 SSDS Image, M106 courtesy of Western Washington University, M106 Core courtesy of Lowell Observatory, M106 2MASS Image, M106 image courtesy of Hunter Wilson (Wikipedia) and M106 image courtesy of N.A.Sharp, REU program NOAO/AURA/NSF.

Object Name: Messier 105
Alternative Designations: M105, NGC 3379
Object Type: E1 Elliptical Galaxy
Constellation: Leo
Right Ascension: 10 : 47.8 (h:m)
Declination: +12 : 35 (deg:m)
Distance: 38000 (kly)
Visual Brightness: 9.3 (mag)
Apparent Dimension: 2.0 (arc min)

Locating Messier 105: Begin your starhop for this great galaxy by identifying Alpha Leonis (Regulus), the brightest star in the backwards question mark that is the signature asterism of the constellation of Leo. Now, look east for the shallow triangle that marks the Lion’s hips. Your next marker is the southwestern star – Theta. Between them, on the belly of the Lion, you will see another faint, but unaided eye visible star. You’ll find Messier 105 just about two degrees (a fingerwidth) to the southeast of this star. If you cannot see this star, chances are you won’t be able to see this egg-shaped elliptical galaxy, either. From a clear, dark sky it can be spotted in larger binoculars and is fairly easy with a small telescope. While larger aperture will make the galaxy appear brighter and somewhat misty around the edges, elliptical galaxies do not produce much detail.

What You Are Looking At: Hanging out with the Leo 1 galaxy group some 38 million light years from our solar system, this ancient galaxy sports a core region that contains about 50 million times more mass than our own Sun. What is it? You got it. A black hole. “We combine Hubble Space Telescope spectroscopy and ground-based integral-field data from the SAURON and OASIS instruments to study the central black hole in the nearby elliptical galaxy NGC 3379. These models also probe the velocity distribution in the immediate vicinity of the black hole and reveal a nearly isotropic velocity distribution throughout the galaxy and down to the black hole sphere of influence RBH. The morphology of the nuclear gas disc suggests that it is not in the equatorial plane; however the core of NGC 3379 is nearly spherical. Inclined thin-disc models of the gas find a nominal black hole of mass (2.0 +/- 0.1) × 108Msolar (3sigma errors), but the model is a poor fit to the kinematics. The data are better fit by introducing a twist in the gas kinematics (with the black hole mass assumed to be 2.0 × 108Msolar), although the constraints on the nature and shape of this perturbation are insufficient for more detailed modelling.” says K.A. Shapiro (et al). “Given the apparent regularity of the gas disc appearance, the presence of such strong non-circular motion indicates that caution must be used when measuring black hole masses with gas dynamical methods alone.”

And it is the gas (or lack thereof) that keeps astronomers going back to study M105. Is it possible that there is not only one – but two – black holes within its core? “Such a small amount of gas can be supplied by stellar mass loss in only 107 yr. Thus, the gas must be accreting into the central supermassive black hole at a very low radiative efficiency as in the ADAF or RIAF models, or it is being expelled in a galactic wind driven by the same AGN feedback mechanism as that observed in cluster cooling flows. If the gas is being expelled in an AGN-driven wind, then the ratio of mechanical to radio power of the AGN must be 104, which is comparable to that measured in cluster cooling flows that have recently been perturbed by radio outbursts. Only 8% of the detected point sources are coincident with globular cluster positions, which is significantly less than that found among other elliptical galaxies observed by Chandra. The low specific frequency of globular clusters and the small fraction of X-ray point sources associated with globular clusters in NGC 3379 is more similar to the properties of lenticular galaxies rather than elliptical galaxies.” says Laurence P. David, (et al).

“The brightest point source in NGC 3379 is located 360 pc from the central AGN with a peak luminosity of 3.5 × 1039 ergs s-1, which places it in the class of ultraluminous X-ray point sources (ULXs). Analysis of an archival ROSAT HRI observation of NGC 3379 shows that this source was at a comparable luminosity 5 yr prior to the Chandra observation. The spectrum of the ULX is well described by a power-law model with ? = 1.6 ± 0.1 and galactic absorption, similar to other ULXs observed by Chandra and XMM-Newton and to the low-hard state observed in Galactic black hole binaries. During the Chandra observation, the source intensity smoothly varies by a factor of 2 with the suggestion of an 8-10 hr period. No changes in hardness ratio are detected as the intensity of the source varies. While periodic behavior has recently been detected in several ULXs, all of these reside within spiral galaxies. The ULX in NGC 3379 is the only known ULX in an elliptical galaxy with a smoothly varying light curve suggestive of an eclipsing binary system.”

Is this structure a probable result of interaction with neighboring galaxies in the group? “The central regions of the three brightest members of the Leo I galaxy group—NGC 3368, NGC 3379, and NGC 3384—are investigated by means of two-dimensional spectroscopy. In all three galaxies we have found separate circumnuclear stellar and gaseous subsystems—more probably, disks—whose spatial orientations and spins are connected to the spatial orientation of the supergiant intergalactic H i ring reported previously by Schneider et al. and Schneider. In NGC 3368 the global gaseous disk seems also to be inclined to the symmetry plane of the stellar body, being probably of external origin.” says O. K. Sil’chenko (et al). “Although the rather young mean stellar age and spatial orientations of the circumnuclear disks in NGC 3379, NGC 3384, and NGC 3368 could imply their recent formation from material of the intergalactic H i cloud, the timescale of these secondary formation events, on the order of 3 Gyr, does not support the collision scenario of Rood & Williams but is rather in line with the ideas of Schneider regarding tidal interactions of the galaxies with the H i cloud on timescales of the intergroup orbital motions.”

History: M105 was discovered by Pierre Mechain on March 24, 1781, actually 3 days before catalog number M101 was discovered. Although most claim there wasn’t any reason that it wasn’t included in Charles Messier’s published list, it was a bad time for Messier who had just lost his wife and newborn son and it would be easy to make a mistake or overlook an observation. Mechain described this object in his letter of May 6, 1783: “Mr. Messier mentions there on page 264 and 265 two nebulous stars, which I have discovered in the Lion [Leo; M95 and M96]. I find nothing to correct for the given positions which I have determined by comparison of their situation with respect to Regulus. There is, however, a third one, somewhat more northerly, which is even more vivid [brighter] than the two preceding ones [M95 and M96]. I discovered this one on March 24, 1781, 4 or 5 days after I had found the other two. On April 10, I compared its situation with Gamma Leonis from which followed its right ascension 159d 3′ 45″ and its northern declination of 13d 43′ 58”.

Messier 105 would be later recovered by Sir William Herschel who believed he was looking at multiple nebulae: “If it was supposed that double nebulae at some distance from each other would frequently be seen, it will now on the contrary be admitted that an expectation of finding a great number of attracting centers in a nebulosity of no great extent is not so probable; and accordingly observation has shewn that greater combinations of nebular than those of the foregoing article.” His son, John, would also observe M105 and give it a catalog designation as well.

However, it was Admiral Smyth who described it eloquently; “A pair of bright-class nebulae, sp [south preceding, SW] and nf [north following, NE] of each other, on the Lion’s belly, discovered by WH [William Herschel] in March, 1783, and No. 758 [NGC 3384] in his son’s Catalogue; while at a small distance to the nf [north following, NE] is a neat but minute double star. These are two of the three nebulae described by both Herschels [M105 and NGC 3384]; but the third [NGC 3389] I cannot distinguish, unless it be a glow in the sf [south following, SE], in a vertical line with two small stars. We now approach a region where these mysterious luminous masses are scattered over the vast concavity of the heavens, in truly boundless profusion; and in them, all true Herschelians must view mighty laboratories of the Universe, in which are contained the principles of future systems of suns, planets and satellites! The objects here treated of, are among the nebulae included within a round patch of about 2 deg or 3 deg in diameter, in the apparently starless space of the Lion’s loins. Now the observer unprovided with an equatorial instrument – and unfortunately many of Urania’s most zealous followers are in that predicament – may wish to fish it up. If his telescope be of capacity for grasping sufficient light, the field may be found, under a moderate power, south of the line which joins Regulus and Theta Leonis about 10 deg east of, and nearly on the parallel with, the former.”

Enjoy your own look into these “mighty laboratories of the universe”!

Top M105 image credit, Palomar Observatory courtesy of Caltech, M105 Black Hole courtesy of Karl Gebhardt (University of Michigan), Tod Lauer (NOAO), and NASA, M105 rotation courtesy of Ohio State University, M105 2MASS image, M105 group image by Isaac Newton Telescope and M105 image courtesy of NOAO/AURA/NSF.