Category: Astrophotos

“Fly me to the Moon and let me play among the stars… Let me see what life is like on…” Oh, hi there! I’ll just bet you know what’s up with the double image, don’t you? That’s right. A little “stereo magic” by Jukka Metsavainio. But this time you’re in for something really different. Step inside for a magic carpet ride you’ll never forget…

This time our visualization moves! That’s right. You’re going to take a virtual 3D journey along the lunar surface… Just like you were flying along in your own personal lunar lander. While Jukka has instructed that this video was prepared in parallel vision only, I had no trouble slightly crossing my eyes and getting it to work for me that way. I hope you’ll find this as exciting as I did! (And I hope you’re able to see it. Remember, not everyone can…)

As you watch the scenery unfold, see how many craters you can identify as we tour from the lunar south to north. I see Maurolycus and Stofler drift by… Then you can see the huge central peak in Arzachel sticking up out of the shadows! Next thing you know, there’s Albategnius with its vacant looking floor and central peak. Ptolmaeus, Hipparchus, Mare Vaporum… Then look out! Vrrrrrrrrooooooom…. Here come the Apennine Mountains with the deep wells of Aristillus and Autolycus on one side and the smooth plains of Mare Serenitatis on the other. Next thing you know? We’re flying over the Caucasus Mountains and you can see the Alpine Valley like the lunar Grand Canyon… and over there! Over there is Atlas and Hercules! And all the way up at the top? Ah… Goldschmidt! Now, if you’ll pardon me. I’ve got a carpet to catch.

Again!

Many thanks to Northern Galactic member, Jukka Metsavainio for sharing his incredible visions with us. We understand how many hours upon hours it takes to do this, and we cannot thank you enough.

[/caption]

Almost everyone who is familiar with space images has seen this beautiful and color emission and reflection nebula – but take a really close look. This isn’t a Hubble image. It was done with a ground based camera!

When looking at M20 through a telescope, what you will see won’t match the photo above, while what is normally presented in science journals is colorful. Why? Well, when it comes to photographs, exposure times and wavelengths causes the different colors you see. Photographically, the red emission nebula contained within Messier 20 has a bright blue star cluster in it central portion. It glows red because the ultraviolet light of the stars ionizes the hydrogen gas, which then recombines and emits the characteristic red hydrogen-alpha light captured on film. Further away, the radiation from these hot, young stars becomes too weak to ionize the hydrogen. Now the gas and dust glows blue by reflection!

Of course, there are other ways of looking at Messier objects, too. It was my great fortune on Saturday night to have an opportunity to study M20 through an image intensifier – a highly complex piece of equipment which uses x-rays and produces a ‘live’ image feed which is displayed on a binocular like eyepiece screen. I cannot even begin to describe to you what this does to observing, except to say that it opens a dimension to to eyes never before experienced. No matter how it is observed, the Trifid – or “three lobed” nebula has a distinctive set of dark dust lanes which divide it. These also have a classification of their own and were cataloged by E.E. Barnard as dark nebula Barnard 85 (B 85).

In 1999 the Hubble Space Telescope took this photograph – a look deep into the Trifid nebula at some of its star forming regions and found a stellar jet poking its way into the cloud, like a fabulous twisted antenna. Inside the exhaust column is a new star waiting to be born, yet sometime over the next 10,000 years the central massive star will probably erode away all of its material before it can fully form. Nearby a stalk stands waiting… Like the jet, it is also a stellar nursery – one with an EGG (evaporating gaseous globule) at its tip – a condensed cloud of gas able to survive so far. “If our interpretation is correct, the microjet may be the last gasp from a star that was cut off from its supply lines 100,000 years ago.” says Jeff Hester of the Department of Physics & Astronomy, “The vast majority of stars like our sun form not in isolation, but in the neighborhood of massive, powerful stars. HST observations of the Trifid Nebula provide a window on the nature of star formation in the vicinity of massive stars, as well as a spectacular snapshot of the “ecology” from which stars like our sun emerge.”

But, is it possible for those of us here on the ground to perform our own deep studies of regions of space like the Trifid Nebula? The answer is yes. Take a look at this small frame clipped from the full sized image you see above. While the colors haven’t been processed the same, those EGGs are there!

It’s a cinch that those of us that don’t have a multitude of titles behind our names are ever going to be allowed Hubble time… even at this late stage of the game. You know our findings will never be placed in the hallowed journals of science. But, why should the scientists be allowed to have all the fun? While images like Eddie’s might be considered “amateur”, it is anything but. While he’s chosen to reveal it in an artistic format, you must stop to think about how much information has been collected inside of his raw data. Unlike a simple film photograph, CCD imaging gathers huge amounts of information that’s processed out by what data is desired. “Velocity maps of the inner regions of the bright H II regions NGC 6514 were made with unprecedented spatial and spectral resolution in the 5007 A line of forbidden O III. In addition to the advantages of an instrumental full width at half-maximum intensity of only 5.4 km/s, the small thermal width of the heavy oxygen ion also allows determination of accurate line widths and velocities.” says C.R. O’Dell (et al), “The CCD spectra were numerically fitted to Gaussian line profiles and revealed two separate velocity systems in NGC 6523. The data sets of radial velocities were used to derive the dependence of the most probable turbulent velocities upon the sample sizes, and the spatial dependence of the structure function. These relationships are the basic functions for comparison with the predictions of the models for turbulence in H II regions.”

To me, one of the most fascinating aspects of Mr. Trimarchi’s picture wasn’t so much the huge revelation of all the Herbig-Haro objects – but a tiny, fine detail that you probably took for granted when you looked at it. Dust extinction… There’s a lot of very exiting things in that photograph, but there’s a detail he left in there that most other photographers filter out! The studies of C.R. O’Dell taught me to take a much closer look a certain properties in astrophotos, because I might see something that others missed, and in this case its a huge amount of dust extinction which he proved to exist around M20 many, many years ago. (Like back when my telescopes still had training wheels.)

Why are things like that important? In this circumstance, knowing there was more dust there than should have been lead to further investigations – and those in turn led to a discovery: “We report the discovery of a new candidate barrel-shaped supernova remnant (SNR) lying adjacent to M20 and two shell-type features to the north and east of SNR W28.” says F. Yusef-Zadeh (et al), ” Future observations should clarify whether the nonthermal shell fragment is either part of W20 or yet another previously unidentified shell-type SNR.”

Keep those cameras rolling… Who knows what we may find tomorrow?

Many thanks to Eddie Trimarchi of Southern Galactic for sharing this wonderul image with us!

[/caption]

Embedded in the Southern Crown some 424 light years away from us resides an area of incredible beauty surrounded by a dark and dusty beast. The three nebulae NGC 6726-27, and NGC 6729 were first discovered by Johann Friedrich Julius Schmidt, during his observations at Athens Observatory in 1861… a time when what they were was poorly understood. At first glance, one might believe this association of stars to be purely coincidental – a chance meeting of moving stars passing through a dust cloud, much like the Pleiades. But, thank heavens for an astronomer named Marth who independently recovered it in 1864 and began to study it, because there’s a whole lot more here than just a pretty picture.

When Marth recovered Schmidt’s three nebulous regions from his vantange point in Malta, he began a series of observations that would last for several years and lead to findings that would cause astronomers to take second looks at this incredible region known as the Corona Australis Nebula. Why? Because by 1916 both Schmidt and Marth had identified a variable star (R CrA) and a variable nebula within it. Within months, astronomers also realized also noticed that the behaviour of R CrA (variability and environment) was similar to T Tauri.

Buried in its yellowish cocoon near the two bright reflection nebulae, R CrA is a young star still accreting interstellar material on to its surface. But what materials? “The 3 micrometers absorption due to H2O ice was detected in three types of sources including protostars, T Tauri-like stars, and background field stars.” says Masuo Tanaka (et al), “This scattered distribution suggests the significant contribution of the circumstellar hot dust to the H-K color and/or sublimation of H2O ice at the inner region of the circumstellar disk due to heating by protostars. Among them, the optical depth of CO ice in IRS 2 is the largest so far detected. It is found that the absorption feature of each source has almost the same central frequency and FWHM which coincide with the calculated values of small grains with dominant CO mantle. On the other hand, the column density of CO ice is found to be substantially smaller than that of H2O ice.”

However, when examined in infrared, two distinct red patches can also be seen hiding inside the beast – Herbig Haro objects. Are these what account for the variability of the nebula? “We suggest that these variations are the result of variable obscuration, possibly linked to dust shells physically associated to the system.” says L.P. Vaz (et al), “NGC 6729 is part of a nebulous region that contains both variable stars R CrA and detached Herbig Be eclipsing binary TY Coronae Australis. We present the non-eclipse-related photometric variability of the system.” Regions that are constantly changing, yet show visible signs of star formation occurring deep inside the dark dust clouds… Coughed out from the hidden star-forming beast (often in pairs) and sent flying in an opposite direction.

Just how long ago were these expelled? According to recent research the primary TY CrA star is difficult to pinpoint, but may be around 3.16 million years old zero-age main sequence, and its secondary star is a pre-main-sequence star located at the base of the Hayashi tracks. It simply isn’t very evolved yet and could be as young as 1.64 million years or as old as 3 million. “All genuine Herbig stars in our sample are located between the birthline and the zero-age main sequence (ZAMS) in the Hertzsprung-Russell diagram (HRD), in accordance with what is expected for pre-main sequence stars.” says M.E. van den Ancker (et al), “The region in the HRD close to the birthline is relatively devoid of stars when compared to the region closer to the ZAMS, in agreement with the expected evolutionary time scales. The Herbig Ae/Be stars not associated with star forming regions were found to be located close to the ZAMS.”

But it is the combination of the beauty of new star formation and the beast of the dust that make the Corona Australis Nebula such a wonderful area for study. By studying polarization, we learn so much more about what is hidden inside. For example, dark dust clouds with embedded star clusters have a more complex distribution of polarization direction than do clouds without clusters, and it is believed that young stars and dense gases are a major factor in the enhanced dispersion of polarization angle – not just quantity of stars. Yet we can take an even closer look! “Polarization mapping of the reflection nebula NGC 6729 reveals parallel bands of polarization vectors across the premain sequence stars R and T Cr A. These bands can be explained by dust discs in which the grains are aligned by toroidal magnetic fields. The dust discs are oriented parallel to each other (in projection and possibly in space) in a north-south direction, which is orthogonal to the axis of the CO bipolar outflow from R Cr A observed by Levreault. Optical jets are associated with both stars, two with R Cr A and one with T Cr A, which are either parallel or antiparallel to each other; however, the optical jets are not orthogonal to the planes of the discs, but are inclined at about 60 deg.” says D. Ward-Thompson of Durham University, “A model is suggested in which the optical jets are collimated by a small inner circumstellar disc, which has decoupled from the magnetic field in outer regions because of ambipolar diffusion, and whose orientation is determined principally by the angular momentum. The large outer interstellar disc, in which the grains are aligned by a toroidal magnetic field, is inclined obliquely to the inner disc and is responsible for the collimation of the CO bipolar outflow.”

Is is the dark clouds of the beast hiding the beauty of star formation that causes the variability? “Measurable changes in the surface brightness of the reflection nebula associated with R CrA occur over intervals as short as 24 hours. These and other more extreme variations are demonstrated with CCD images obtained over a 23-day period. During this time span R CrA brightened by 1.3 mag.” says J.A. Graham, “The alterations in the appearance of the nebula NGC 6729 are apparently caused by the shadowing effects of clouds which are very close to the star, probably well within 1 Au. The spectrum of R CrA may itself vary slightly from night to night, and these changes are echoed by the surrounding nebula with an observable time delay.”

Will we ever know everything there is to know about the Beauty and the Beast? What we do know is: “The the Corona Australis molecular cloud complex is one of the nearest regions with ongoing and/or recent star formation. It is a region with highly variable extinction, containing, at its core, the Coronet protostar cluster. There are now 55 known optically detected members, starting at late B spectral types. At the opposite end of the mass spectrum, there are two confirmed brown dwarf members and seven more candidate brown dwarfs. The Corona Australis molecular cloud complex is today known as one of the nearest regions with ongoing and/or recent intermediate- and low-mass star formation.” says Ralph Neuhauser of Astrophysikalisches Institut und Universitats-Sternwarte, “In between the stars R and T CrA, there is the reflection nebula NGC 6729, and the stars TY CrA and HD 176386 illuminate the nebula NGC 6726/6727. Studying lines of CN, CH, and CH in the direction of TY CrA, find that the dust in the region which is attenuating the UV emission is highly processed and strong extended emission is possibly due to polycyclic aromatic hydrocarbons (PAHs).”

Our thanks to Eddie Trimarchi of Southern Galactic for sharing this awesome photo with us!