Universe Today

January 14, 2009December 24, 2015 by Tammy Plotner

Scutum

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The small constellation of Scutum was originally created by Johannes Hevelius in 1683 and was later adopted as a permanent constellation by the IAU. It resides just north of the ecliptic plane or about 10 degrees south of the celestial equator and spans 109 square degrees of sky, ranking 84th in constellation size. There are 2 main stars in Scutum’s asterism and it contains 7 Bayer Flamsteed designated stars within its confines. It is bordered by the Aquila constellation, Sagittarius and Serpens Cauda. Scutum is visible to all observers located at latitudes between +80° and ?90° and is best seen at culmination during the month of August.

There is one annual meteor shower associated with the constellation of Scutum – the June Scutiids. Beginning on or about June 2 and ending about July 29th, we pass into the meteoroid stream which brings on the activity. The peak date for this meteor shower is on or about June 27 and the maximum fall rate is 2-4 meteors per hour.

The constellation of Scutum wasn’t named for a mythological figure – but rather for an object to honor a classical one. In, 1683, Johannes Hevelius, who originally named it Scutum Sobiescianum (the shield of Sobieski), did to commemorate the victory of the Polish forces led by King John III Sobieski in the Battle of Vienna, and thus the name refers to Sobieski’s Janina Coat of Arms. Rather fitting, since this particular king helped Hevelius rebuild his observatory after it was destroyed by fire! It’s Latin name means “shield” and the name was later shortened to Scutum when it was adopted as a permanent constellation by the International Astronomical Union.

Let’s begin our binocular tour of Scutum with its brightest star – Alpha – the “a” symbol on our map. Alpha Scuti is an orange class K giant star located about 175 light years from Earth. While it is not uncommon for this type of star to be over 130 times brighter than our Sun and more than 20 times larger – what’s unusual is the way it has evolved. According to its mass, Alpha should be about 2 billion years old and beginning to fuse helium to carbon… However, it has been discovered that Alpha is slightly variable – meaning it could be shedding its outer layer and on the way to becoming a white dwarf star!

Now, have a look at Delta – the “8” symbol on our chart. Here’s a peculiar star if there ever was one… A star so strange that it’s the prototype of its class. Delta is a giant star – but it is also a variable star. Located 187 light years from our solar system, this metal-rich oddity shines 33 times brighter than our Sun, but it’s only about twice as big. Deep inside, it has stopped fusing hydrogen and it is on its way to becoming a red giant star. But, it’s pulsing like a heartbeat… Changing its magnitude by about 20% every 5 to 65 hours. Added to this are periods of 2.79 hours, 2.28 hours, 2.89 hours, and 20.11 hours. All of this adds up to a very complex rhythm which makes Delta unique! Now, take a look in a telescope, too… Because Delta isn’t alone – it is also a binary star. Look for a 12th magnitude companion 15.2 seconds of arc away from the primary and a 9th component 52.2 seconds away.

For binoculars and small telescopes, head off to Messier 11 (RA 18 : 51.1 Dec -06 : 16)! This incredible galactic star cluster was discovered in 1681 by German astronomer Gottfried Kirch at the Berlin Observatory, M11 was later cataloged by Charles Messier in 1764 and first dubbed the “Wild Duck” by Admiral Smyth. To our modern telescopes and binoculars, there is little doubt as to how this rich galactic cluster earned its name – for it has a distinctive wedge-shaped pattern that closely resembles a flight of ducks. This fantastic open cluster of several thousand stars (about 500 of them are magnitude 14 or brighter) is approximately 250 million years old. M11 is easily located by identifying Altair, the brightest star in Aquila. By counting two stars down the “body” of Aquila and stopping on Lambda, you will find your starhop guide. Near Lambda you will see three stars, the centermost is Eta Scuti. Now just aim! Even small binoculars will have no problem finding M11, but a telescope is required to start resolving individual stars. The larger the telescope’s aperture the more stars will be revealed in this most concentrated of all open clusters!

Keep binoculars and rich field telescopes handy as you shift over to Alpha Scutum and check east-northeast for neighboring 7.8 magnitude open cluster NGC 6664 (RA 18 : 36.7 Dec -08 : 13) . Compare the view to Scutum’s other Messier open cluster – similar sized M26 (RA 18 : 45.2 Dec -09 : 24). As one of the faintest Messier clusters, it’s surprising his scope was able to reveal it at all! To locate Messier 26 shift a little less than 3 degrees south-southeast of Alpha. Those with larger scopes should look for a strange void in the middle of the cluster.

Now, let’s go with a large telescope and have a look at globular cluster NGC 6712 (RA 18 : 53.1 Dec -08 : 42). At magnitude 8, it can be captured with smaller aperture, but requires some muscle to resolve! NGC 6712 was probably discovered by Le Gentil on July 9, 1749 when investigating the Milky Way star cloud in Aquila, but we know it was independently discovered by William Herschel on June 16, 1784. As for its nature? That took John Herschel, who was the first to described it as a “globular star cluster” during his observations in the 1830s!

Last, but not least, let’s do something that you don’t even need a telescope for – R Scuti. This terrific red variable star ranges from 4th to 8th magnitude in 142 days. Chances are, R is probably a red supergiant star, surrounded by a shell of material thousands of times bigger than the interior star itself. One day, it will drop its envelope – turning into a planetary nebula and the star into a white dwarf… But until then? We can simply enjoy this beautiful mystery star!

Sources:
Wikipedia
SEDS
Chandra Observatory
Chart Courtesy of Your Sky.

January 14, 2009December 24, 2015 by Tammy Plotner

Sculptor

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The small constellation of Sculptor is located south of the ecliptic plane. It was originally charted by Abbe Nicolas Louis de Lacaille who named it “Apparatus Sculptoris” – the Sculptor’s Studio. It was later adopted by the International Astronomical Union as one of the 88 modern constellations and its name shortened to Sculptor. It covers 475 square degrees of sky and ranks 36th in constellation size. Sculptor has 4 main stars in its asterism and contains 18 Bayer Flamsteed designated stars within its boundaries. It is bordered by the constellations of Cetus, Aquarius, Piscis Austrinus, Grus, Phoenix and Fornax. Sculptor is visible to all observers located at latitudes between +50° and ?90° and is best seen at culmination during the month of November.

Since Sculptor is considered a “new” constellation, there is no mythology associated with it – only the story of how its name came to be. French astronomer Nicolas Louis de Lacaille charted the southern hemisphere skies from the Cape of Good Hope during the time period of 1751-1752 and his love of all objects in art and science were portrayed in the names he assigned to his newly created constellations. Depicted on his chart as a fanciful tripod with a carved bust and the artist’s tools, ” l’Atelier du Sculpteur” was later shortened to the simpler term – Sculptor – and adopted by the International Astronomical Union as a permanent constellation.

Let’s begin our binocular tour of Sculptor with its brightest star – Alpha – the “a” symbol on our map. Located approximately 680 light years from Earth, Alpha Sculptoris is a blue-white B-type giant classified as an SX Arietis type variable star and its magnitude varies by 0.01. While changes in brightness and spectral composition that small would never be detectable to the human eye, at one time it was believed to be caused by orbiting black hole – but were later identified to chemical variations in its atmosphere. While Alpha doesn’t appear to be much, take a closer look… It still shines over 1700 times brighter than our own Sun – yet is only 7 times larger! It is one of the weirdest stars you will ever see – a helium weak star that rotates ever-so-slowly. Thanks to this creeping motion, Alpha can generate a huge stellar magnetic field which allows it to concentrate its chemicals in certain areas – and even flip its magnetic poles!

For other binocular attractions, take a look at Beta Sculptoris – the “B” symbol. It’s a a blue-white B-type subgiant star positioned approximately 178 light years from our solar system. Or Gamma – the “Y” symbol – it’s an an orange K-type giant that is 179 light years away… or even Delta – the “8” symbol. Delta is is a triple star system that’s 139 light years distant and the primary component, Delta Sculptoris A, is a white A-type main sequence dwarf star! Take out the telescope and look for a faint, 11th magnitude companion, Delta Sculptoris B, 4 arcseconds, or more than 175 AU, away from it. Orbiting this pair at the much greater separation of 74 arcseconds, is the third player in this drama, the yellow G-type Delta Sculptoris C, which has an apparent stellar magnitude of 9.4.

For telescope observers, one of the greatest challenges you will ever encounter is the Sculptor Dwarf Galaxy (RA 01 : 00.0 Dec -33 : 42). Discovered by Harlow Shapley on photographic plates in 1937, this extreme low surface brightness elliptical galaxy is a member of our own local galaxy group and is about 290,000 light-years away. Use at least a 150mm telescope and an absolute minimum of magnification to spot just a compression in the starfield at this location!

Now, let’s take a look at the Sculptor Group – a a loose group of galaxies near the south galactic pole and one of the closest groups of galaxies to the Milky Way Local Group. At the head of this class is the Sculptor Galaxy – NGC 253 – is an intermediate spiral galaxy (RA 0 : 47.6 Dec -25 : 17). Discovered by Caroline Herschel, this brilliant magnitude 7 beauty is a starburst galaxy, undergoing periods of intense star formation, and can easily be seen with a small telescope or binoculars. However, companion galaxies NGC 247, PGC 2881, PGC 2933, Sculptor-dE1, and UGCA 15 will need much more aperture! This association forms a gravitationally bound core near the center of the group and most other galaxies associated with the Sculptor Group are only weakly gravitationally bound to this core.

While there, drop south and take a look at NGC 288 (RA 00:52:47.5 Dec -26:35:24). This 8th magnitude globular cluster was discovered by Sir William Herschel and can often be spotted in the same binocular field as NGC 253. While this small globular doesn’t appear to be worthy of much attention, think again… In the late 1980’s it was discovered that it is about 3 billion years older than other globular clusters!

Need to take a look at the home of a supernova? The stop by NGC 150 (RA 0 : 34.3 Dec -27 : 48). Home to an event in 1990, this spiral galaxy is also a great radio emitter, too. Even though it will require a larger telescope to catch anything at magnitude 11, it will still give a nice oblong presentation with a bright core region.

For another binocular and small telescope galaxy, take a look at NGC 55 (RA 0 : 14.9 Dec -39 : 11). This huge, magnitude 8 irregular galaxy gives a great, near edge-on presentation and is believed to be very similar to the Large Magellanic Cloud (LMC). Spanning about 50,000 light-years, large telescopes will be able to resolve out brighter regions of emission nebulae – large star forming regions producing new stars.

For an unusual mid-size telescope challenge, take a look at NGC 7793 (RA 23 : 57.8 Dec -32 : 35). At magnitude 9 and about 9 arc minutes in size, you’ll find 10 million light year distant Bennett 130 to be a beautiful spiral with a sharp nucleus and round, hazy spiral galaxy structure. It was discovered by James Dunlop and it is also part of the Sculptor Group. In 2005, the Spitzer Space Telescope was able to pierce through its clouds and take a closer look at star formation driving the evolution of the galaxy.

Don’t forget while you’re in Sculptor to take on large telescope challenges like NGC 7713 (RA 23 : 36.5 Dec -37 : 56) – a 12th magnitude spiral galaxy, NGC 7755 (RA 23 : 47.9 Dec -30 : 31), also 12th magnitude, but a much smaller elliptical galaxy. How about small and faint NGC 24 (RA 0 : 09.9 Dec -24 : 58) or far easier NGC 134 (RA 0 : 30.4 Dec -33 : 15). There’s galaxies galore just waiting to be carved out of Sculptor and enjoyed!

Sources:
SEDS
Chandra Observatory
Wikipedia
Chart Courtesy of Your Sky.

January 13, 2009December 24, 2015 by Nancy Atkinson

Viewing Earth as an Extra-Solar Planet

Earth scenes and corresponding spectra reconstructed for two observer’s positions. Credit: Arnold, et al.

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What if another civilization had telescopes and spacecraft better than ours? Would Earth be detectable from another planet a few light-years away? Likewise, what will it take for us to detect life on an Earth-like planet within a similar distance? It’s interesting to consider those questions, and now, there is data to help answer them. In December 1990, when the Galileo spacecraft flew by Earth in its circuitous journey to Jupiter, scientists pointed some of the instruments at Earth just to see how the old home planet looked from space. Since we knew life could definitely be found on Earth, this exercise helped create some criteria that if found elsewhere, would point to the existence of life there as well. But what if Earth’s climate was different from what it is now? Would that signature still be detectable? And could potential biomarkers from extra solar planets holding climates much colder or warmer than ours be obvious? A group of researchers in France input some various criteria garnered from different epochs in Earth’s history to test out this hypothesis. What did they find?

One of the most telling of the criteria from the Galileo flyby revealing life on Earth was what is called the vegetation red edge –a sharp increase in the reflectance of light at a wavelength of around 700 nanometers. This is the result of chlorophyll absorbing visible light but reflecting near infrared strongly. The Galileo probe found strong for this evidence on Earth in 1990.

Luc Arnold and his team at the Saint-Michel-l’Observatoire in France wanted to determine some different parameters where plant life similar to Earth’s would still be detectable via the vegetative red edge on an Earth-like planet orbiting a star several light years away.

At that distance the planet would be a non-resolvable (in visible light) point-like dot, so the first question to consider is whether the red edge would be visible at different angles. The planet is likely to be rotating, and for example, on Earth, the continents that have the most vegetation are mainly in the northern hemisphere. If that hemisphere wasn’t leading the view, would a bio-signature still be detectable? They also wanted to allow for the different seasons, where a hemisphere in winter would be less likely to have vegetative biomarkers than one in summer, and potential heavy cloud cover.

They also input different climate criteria from the last Quaternary climate extremes, using climate simulations have been made by general circulation models. They used data from the present time and compared that to an ice age, The Last Glacial Maximum (LGM) which occurred about 21,000 years ago. Temperatures globally were on the order of 4 degrees C colder than today, and ice sheets covered most of the northern hemisphere. Then, they used a warmer time, during the Holocene epoch 6,000 years ago, when the Earth’s northern hemisphere was about 0.5 degrees C warmer than today. The sea level was rising and the Sahara Desert contained more vegetation.

Surprisingly, the researchers found even during winter in an ice age, the vegetation red signal would not be significantly reduced, compared to today’s climate and even the warmer climate.

So if another Earth is out there, the vegetaion red edge should allow us to find that Earth-like planet. But we need better telescopes and spacecraft to find it.

The best hope on the horizon is the Terrestrial Planet Finder. ESA has a similar instrument in the works called Darwin.
The teams behind these instruments say they could spot Earth-like planets orbiting stars at distances of up to 30 light years with an exposure measured in a couple of hours.

Arnold’s team says that spotting the signs of life on such a planet would be much harder. The vegetation red edge might only be seen with an exposure of 18 weeks with a telescope like the Terrestrial Planet Finder’s. An 18 week exposure of a planet orbiting another star would be an almost impossible task.

So when might we eventually see vegetation on another planet? The Terrestrial Planet Finder (TPF) looks unlikely to be launched before 2025 and even then might not have the power to do the job.

More ambitious telescopes later in the century, such as a formation of 150 3-meter mirrors would collect enough photons in 30 minutes to freeze the rotation of the planet and produce an image with at least 300 pixels of resolution, and up to thousands depending on array geometry. “At this level of spatial resolution, it will be possible to identify clouds, oceans and continents, either barren or perhaps (hopefully) conquered by vegetation,” the researchers write.

Sources: arXiv, arXiv blog

January 13, 2009December 24, 2015 by Tammy Plotner

Scorpius

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The zodiacal constellation of Scorpius resides on the ecliptic plane and was one of the original 48 constellations charted by Ptolemy to be later adopted as a modern constellation by the IAU. It covers 497 square degrees of sky and ranks 33rd in size. Scorpius has 15 main stars in its asterism and 47 Bayer Flamsteed designated stars within its confines. It is bordered by the constellations of Sagittarius, Ophiuchus, Libra, Lupus, Norma, Ara and Corona Australis. Scorpius is visible to all observers located at latitudes between +40° and ?90° and is best seen at culmination during the month of July.

There are two annual meteor showers associated with the constellation of Scorpius. The first is the Alpha Scorpiids – which begin on or about April 16 and end around May 9. The peak date of most activity is on or about May 3 and the radiant is near the brilliant red star, Antares. The second meteor shower, the June Scorpiids peaks on or about June 5 of each year. The radiant for this particular meteor shower is closer to the Ophiuchus border and the activity rate on the peak date is high – with about 20 meteors (average) per hour and many reported fireballs.

Because Scorpius was easy visible to ancient civilizations and its patterns do resemble the Scorpion which it represents, there is a great deal of mythology associated with this constellation. To the Greeks it represented the creature sent by Hera to eliminate Orion the Hunter – forever kept apart in the sky to continue their heavenly feud. Perhaps it was Apollo who sent the Scorpion and Orion flees it? Scorpius was also said to appear to Phaethon, who wrecked the sun-chariot when the horses balked at the mighty monster’s appearance. The Oriental culture recognized this pattern of stars as part of the Dragon, while the Polynesians saw it as a fishhook. No matter what legend you choose to place on this pattern of stars, its curving asterism is very distinctive and easy to recognize!

Let’s begin our binocular tour of Scorpius with its brightest star – Alpha – the “a” symbol on our chart. Antares is part of of the Upper Scorpius Association of Stars and is no doubt also a star poised on the edge of extinction. At a safe distance of 500 light-years, you’ll find this pulsating red variable equally fascinating to the eye as well as to the telescope. Unlike other stars, Alpha Scorpii also has a companion which can be revealed to small telescopes under steady conditions. Discovered on April 13, 1819 during a lunar occultation, this 6.5 magnitude green companion isn’t the easiest to split from such a bright primary – but it’s certainly fun to try to spot its 5.4 magnitude green companion. Like winter’s Sirius, the Antares pair needs especially still – but not necessarily dark – skies. It also requires a well-chosen magnification – one high enough to separate the two close stars (2.9 arc seconds), but low enough to concentrate the fainter star’s (magnitude 5.4) light. Did you know that Antares’ true rival is brighter Betelgeuse? Photometric measurements show that more massive Betelgeuse is slightly redder than Antares. Fortunately, the “Rival” does reside along the ecliptic plane allowing us many opportunities to see it accompany other solar system objects and be occulted by the Moon!

Keep your binoculars handy because all you have to know is Antares and go west…

Just slightly more than a degree away you’ll find a major globular cluster perfectly suited for every size telescope and binoculars – M4 (RA 16 23 35 Dec 26 31 31). This 5th magnitude Class IX cluster can even be spotted unaided from a dark location! In 1746 Philippe Loys de Cheseaux happened upon this 7200 light-year distant beauty – one of the nearest to us. It was also included in Lacaille’s catalog as object I.9 and noted by Messier in 1764. Much to Charles’ credit, he was the first to resolve it!

As one of the loosest globular clusters, M4 would be tremendous if we were not looking at it through a heavy cloud of interstellar dust. To binoculars, it is easy to pick out a very round, diffuse patch – yet it will begin resolution with even a small telescope. Large telescopes will also easily see a central “bar” of stellar concentration across M4’s core region, which was first noted by William Herschel. As an object of scientific study, the first millisecond pulsar was discovered within M4 in 1987 – one which spins 10 times faster than the Crab Nebula pulsar. Photographed by the Hubble Space Telescope in 1995, M4 was found to contain white dwarf stars – the oldest in our galaxy – with a planet orbiting one of them! A little more than twice the size of Jupiter, this planet is believed to be as old as the cluster itself. At 13 billion years, it would be three times the age of the Sol system!

Keep your binoculars or a small telescope handy as well go off to explore a single small globular cluster – Messier 80. Located about 4 degrees northwest of Antares (half a fist), this little globular cluster is a powerpunch. Located in a region heavily obscured by dark dust, the M80 will shine like an unresolvable star to small binoculars and reveal itself to be one of the most heavily concentrated globulars to the telescope. Discovered within days of each other by Messier and Mechain respectively in 1781, this intense cluster is around 36,000 light years distant.

In 1860, the M80 became the first globular cluster to contain a nova. As stunned scientists watched, a centrally located star brightened to magnitude 7 over a period of days and became known as T Scorpii. The event then dimmed more rapidly than expected, making observers wonder exactly what they had seen. Since most globular clusters contain stars all of relatively the same age, the hypothesis was put forward that perhaps they had witnessed an actual collision of stellar members. Given the cluster contains more than a million stars, the probability remains that some 2700 collisions of this type may have occurred during the M80’s lifetime.

Now head for Lambda Scorpii and hop three fingerwidths northeast to NGC 6406 (RA 17 40 18 Dec -32 12 00)… We’re hunting the “Butterfly!” Easily seen in binoculars and tremendous in the telescope, this brilliant 4th magnitude open cluster was discovered by Hodierna before 1654 and independently found by de Cheseaux as his Object 1 before being cataloged by Messier as M6. Containing about 80 stars, the light you see tonight left its home in space around the year 473 AD. Messier 6 is believed to be around 95 million years old and contains a single yellow supergiant – the variable BM Scorpii. While most of M6’s stars are hot, blue, and belong to the main sequence, the unique shape of this cluster gives it not only visual appeal, but wonderful color contrast as well.

Less than 3 arc minutes east of 3.3 magnitude G Scorpii (the tail star of the Scorpion) is 7.4 magnitude globular cluster NGC 6441. No challenge here. This 38,000 light-year distant compact cluster is around 13 thousand light-years from the galactic core. It was first noted by James Dunlop from southeastern Australia in 1826.

Around two and a half degrees northeast of G Scorpii (and NGC 6441) is another interesting deep sky twosome – bright open cluster M7 and faint globular NGC 6453. M7 was first recorded as a glowing region of faint stars by Ptolemy circa 130 CE. Located 800 light-years away, the cluster includes more than half a dozen 6th magnitude stars easily resolved with the least amount of optical aid. Through telescopes, as many as 80 various stars can be seen and it rocks in binoculars!

Now head northeast and the faint haze of 31,000 light-year distant globular cluster NGC 6453 will reveal itself to mid- and large-sized scopes. Like NGC 6441, this globular cluster was discovered from the southern hemisphere, in this case by John Herschel on June 8, 1837 while observing from the Cape of Good Hope, South Africa.

It’s time to aim your telescope at NGC 6302, a very curious planetary nebula located around three fingerwidths west of Lambda Scorpii: it is better known as the “Bug” nebula (RA 17 13 44 Dec -37 06 16). With a rough visual magnitude of 9.5, the Bug belongs to the telescope – but it’s history as a very extreme planetary nebula belongs to us all. At its center is a 10th magnitude star, one of the hottest known. Appearing in the telescope as a small bowtie, or figure 8 shape, huge amounts of dust lie within it – very special dust. Early studies showed it to be composed of hydrocarbons, carbonates and iron. At one time, carbonates were believed associated with liquid water, and NGC 6302 is one of only two regions known to contain carbonates – perhaps in a crystalline form.

Ejected at a high speed in a bi-polar outflow, further research on the dust has shown the presence of calcite and dolomite, making scientists reconsider the kind of places where carbonates might form. The processes that formed the Bug may have begun 10,000 years ago – meaning it may now have stopped losing material. Hanging out about 4000 light-years from our own solar system, we’ll never see NGC 6302 as well as the Hubble Telescope presents its beauty, but that won’t stop you from enjoying one of the most fascinating of planetary nebulae!

Now begin your starhop at the colorful southern Zeta pair and head north less than one degree for NGC 6231 (RA 16 : 54.0 Dec -41 : 48). Wonderfully bright in binoculars and well resolved to the telescope, this tight open cluster was first discovered by Hodierna before 1654. De Cheseaux cataloged it as object 9, Lacaille as II.13, Dunlop as 499, Melotte as 153, and Collinder as 315. No matter what catalog number you chose to put in your notes, you’ll find the 3.2 million year young cluster shining as the “Northern Jewelbox!” For high power fans, look for the brightest star in this group – it’s van den Bos 1833, a splendid binary.

About another degree north is loose open cluster Collinder 316, with its stars scattered widely across the sky. Caught on its eastern edge is another cluster known as Trumpler 24, a site where new variables might be found. This entire region is encased in a faint emission nebula called IC 4628 – making this low power journey through southern Scorpius a red hot summer treat!

When you are done, hop west (RA 16 25 18 Dec 40 39 00) to encounter the fine open cluster NGC 6124. Discovered by Lacaille and known to him as object I.8, this 5th magnitude open cluster is also known as Dunlop 514, as well as Melotte 145 and Collinder 301. Situated about 19 light-years away, it will show as a fine, round, faint spray of stars to binoculars and be resolved into about 100 stellar members to larger telescopes. While NGC 6124 is on the low side for northern observers, it’s worth the wait for it to hit its best position. Be sure to mark your notes, because this delightful galactic cluster is a Caldwell object and a southern skies binocular reward!

There are many, many more splendid object to be discovered in the constellation of Scorpius, so be sure to get a detailed star chart and enjoy!

Sources:
Wikipedia
Chandra Observatory
Chart Courtesy of Your Sky.

January 13, 2009December 24, 2015 by Nancy Atkinson

Aurora Australis at the South Pole

Aurora Australis over the elevated station at Amundsen-Scott South Pole Station, Antarctica. Credit: Calee Allen, National Science Foundation

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I just had to share this gorgeous image of the Aurora Australis over the Amundsen-Scott South Pole Station in Antarctica. “Northerners” like myself occasionally get to see the Aurora Borealis, or Northern Lights, but fewer people get to the the Aurora Australis because so few people live in Antarctica during the austral winter. In both hemispheres however, the cause of these eerie light shows is the same: the solar wind passing through the Earth’s upper atmosphere. This image was taken in May of 2008, but was just recently posted by the National Science Foundation.

Here’s a link to a larger, hi-res version of the image above.

The Amundsen-Scott Station has been open for just a year, and below are more pictures and information.

Amundson-Scott Station. Credit: Keith Vanderlinde, National Science Foundation

Stars are visible in this image, also taken in May of 2008, during the short daytime in the winter at the South Pole. Amundsen-Scott South Pole Station sits at the Earth’s axis, atop a constantly shifting continental ice sheet nearly two miles thick. This is perhaps the world’s most remote research facility,

In January 2008, the National Science Foundation (NSF) dedicated the new station at the Pole, the third since 1956. The new station is larger and much more sophisticated than any previous structure built at the Pole. Research in a range of areas, from astrophysics to seismology, takes place at the station. The new elevated station contains dorm rooms, laboratories, office space, cafeteria and recreational facilities.

If you’d like to keep an eye on what’s going at the Station, there is a live web-cam that updates every 20 seconds.

There’s a huge amount of information about Amundsen-Scott Station at the NSF website.

Source: NSF

January 13, 2009December 24, 2015 by Nancy Atkinson

XMM Newton Zeroes in on Zombie Star

False colour X-ray image of the sky region around SGR 1627-41 obtained with XMM-Newton. Credits: ESA/XMM-Newton/EPIC (P. Esposito et al.)

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Soft Gamma-ray Repeaters (SGRs) are strange and relatively rare objects, with only five known to exist (four in the Milky Way and one in the Large Magellanic Cloud.) Each is between 10 and 30 km across, yet contains about twice the mass of the Sun. SGRs are collapsed cores of large stars that have exploded, called neutron stars, and seemingly, they refuse to die: they will repeatedly flare up after remaining quiet for long periods. Now, ESA’s XMM-Newton spacecraft zeroed in on one of these stellar zombies, SGR 1627-41 revealing it to be extremely unique and unusual.

What sets SGRs apart from other neutron stars is that they possess magnetic fields that are up to 1000 times stronger. This has led astronomers to call them magnetars.

SGR 1627-41 was discovered in 1998 by NASA’s Compton Gamma Ray Observatory when it burst into life emitting around a hundred short flares during a six-week period. It then faded before X-ray telescopes could measure its rotation rate. Thus, SGR 1627-41 was the only magnetar with an unknown period.

But now, XMM Newton was able to determine the rotation rate for the first time: it rotates once every 2.6 seconds. “This makes it the second fastest rotating magnetar known,” says Sandro Mereghetti, INAF/Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan, one of the team.

Theorists are still puzzling over how these objects can have such strong magnetic fields. One idea is that they are born spinning very quickly, at 2-3 milliseconds. Ordinary neutron stars are born spinning at least ten times more slowly. The rapid rotation of a new-born magnetar, combined with convection patterns in its interior, gives it a highly efficient dynamo, which builds up such an enormous field.

With a rotation rate of 2.6 seconds, this magnetar must be old enough to have slowed down. Another clue to the magnetar’s age is that it is still surrounded by a supernova remnant. During the measurement of its rotation rate, XMM-Newton also detected X-rays coming from the debris of an exploded star, possibly the same one that created the magnetar. “These usually fade to invisibility after a few tens of thousand years. The fact that we still see this one means it is probably only a few thousand years old”, says Mereghetti.

If it flares again, the team plan to re-measure its rotation rate. Any difference will tell them how quickly the object is decelerating. There is also the chance that SGR 1627-41 will release a giant flare. Only three such events have been seen in the last 30 years, each from a different SGR, but not from SGR 1627-41.

These superflares can supply as much energy to Earth as solar flares, even though they are halfway across the Galaxy, whereas the Sun is at our celestial doorstep. “These are intriguing objects; we have much still to learn about them,” says Mereghetti.

Source: ESA

January 12, 2009April 26, 2016 by Nancy Atkinson

XCOR Releases New Images of Rocket Test

5K18 "Lynx" engine. Credit: XCOR and Mike Massee

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In December, XCOR Aerospace, Inc. successfully completed its first test fire of the rocket engine that will be used to power its Lynx suborbital launch vehicle to the edge of space. Today, they released some new images of the test that are sure to excite any rocket enthusiast. The new engine, called the 5K18, produces between 2500-2900 lbs of thrust by burning a mixture of liquid oxygen and kerosene. The engine was fired Monday, December 15th, 2008 at XCOR’s rocket test facility located at the Mojave Air and Space Port. XCOR is the company that dropped its price of a suborbital ride to the edge of space to $95,000. The Lynx will use four of the 5K18 engines to carry people or payloads 61 kilometers (37 miles) above the Earth. “Firing a new rocket engine is always an important milestone,” said XCOR COO Andrew Nelson. “It gives everyone on the team a tremendous sense of accomplishment and demonstrates to customers and investors that XCOR knows how to take new ideas and make them a reality.”

The test of the engine was performed using pressure-fed propellants whereas the final version of the engine will be fed using XCOR’s proprietary cryogenic piston pump for liquid oxygen and a similar piston pump for kerosene.

XCOR has been around for nine years, and during that time has built and flown many different engines and conducted over 3,600 hot fires of rocket engines. The 5K18 is the eleventh engine design XCOR has built and fired. All have had perfect safety records, according to XCOR, and they also have not had any lost employee time due to injury during engine operations. It has also never seen one of its engines wear out, which says a lot of the durability of their hardware.

XCOR’s experience also includes building rocket-powered vehicles. The company has already developed and safely flown two generations of rocket-powered aircraft. Overall, the firm has flown these vehicles 66 times, and XCOR alone accounts for more than half of all manned rocket-powered flights in the 21st century. The Lynx will be the company’s third rocket-powered vehicle, and the first designed for space access.

If you’ve got a spare chunk of change and are interested in a suborbital flight with XCOR, RocketShip Tours, of Phoenix, AZ, has begun sales of tickets for suborbital flights on the Lynx.

Source: XCOR

January 12, 2009December 24, 2015 by Nancy Atkinson

Stardust and Aerogel Return Home Again

Artist rendering of Stardust-NeXT spacecraft approaching Earth's gravitational pull, resulting in accelerating of spacecraft and bending of flight path. Courtesy: NASA

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Remember the Stardust mission that returned samples of comet dust back to Earth in 2006? The spacecraft dropped off a capsule containing samples of a comet’s coma and interstellar dust particles, but the spacecraft “bus” is still out there in an elongated orbit of the sun. It will come home again, swinging by Earth on January 14, at 19:40 UTC (12:40 pm PST), getting a gravity assist from the home planet as it flies approximately 5713 miles (9200 kilometers) from the Earth’s surface. But the spacecraft isn’t just wandering the solar system with nothing to do. It has a new job and a new mission. Called Stardust NExT, (New Exploration of Tempel 1) the spacecraft will re-survey comet Tempel 1 – the comet that the Deep Impact mission left a mark on — encountering the comet on Feb. 14, 2011.

And remember aerogel – the wispy material that collected the comet dust? Turns out this stuff can come home, too: into homes and other buildings as a super-insulating material. Engineers say using aerogel as an insulator can increase the thermal insulation factor of a wall by over 40%!

Lightweight, wispy aerogel. Credit: NASA

If you’ve ever had the chance to handle aerogel, you know it’s really weird stuff. It’s fragile, but it’s also strong. You can crush it easily in your hand, but it has just the right qualities to be able to capture dust particles zooming in space at extremely high speeds without breaking, and was “gentle” enough to preserve the particles. Engineers say the aerogel insulation technology developed by NASA, is the highest insulating material in existence, and the company Thermablok(TM) developed an amazing product that may soon become a requirement in the building industry.

Aerogel, also referred to as “frozen smoke,” has been difficult to adapt to most uses because it’s so fragile The patented Thermablok material however overcomes this by using a unique fiber to suspend a proprietary formula of Aerogel such that it can be bent or compressed while still retaining its amazing insulation properties.

Aerogel material is 95% air, and just a 1/4″ x 1-1/2″ (6.25mm x 38mm) strip of Thermablok(TM) added to each stud in a wall before putting on drywall, breaks the “thermal bridging,” increasing the thermal insulation factor of a wall by 42%.

The U.S. Department of Energy has verified the findings on the producst’s thermal capability. Plus its recyclable, fire resistant and not affected by water (so no mold).

Speaking of recyclable, NASA’s plans for the Stardust spacecraft to revisit Tempel 1 will finish the investigation begun in 2005 when the Deep Impact mission blasted a crater into the comet. “The crater’s there,” said Joseph Veverka, Professor of Astronomy at Cornell University and Principal Investigator of Stardust-NExT, “but we’ve never seen it.” That’s because the cloud of material ejected from the crater obscured the Deep Impact spacecraft’s view. By the time the particles slowly settled back down to the comet’s surface, the spacecraft, traveling at about 10 km (about 6 miles) per second, was gone.

Looking into the crater with Stardust-NExT will provide mankind’s first view of a comet’s internal structure, information that is not only scientifically interesting, but vital to our future ability to keep a comet from hitting the Earth. Even the size of the crater will be revealing. “That will tell us the mechanical properties of the subsurface of the comet,” Veverka said. “In other words, how does the comet respond to impacts? And that’s one of the fundamental things that you’d need to know if you were trying to blow up a comet or push it out of the way.”

Stardust was originally launched in 1999, and in January 2004, the spacecraft performed a risky and historic flyby of Comet Wild 2 to capture the samples and take pictures of the comet’s nucleus.

Sources: Space Ref, Stardust NExT mission

January 12, 2009December 24, 2015 by Nancy Atkinson

Profiling Potential Supernovae

Astronomical plate showing Sagittarius. Credit: Ashley Pagnotta

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Just as psychologists and detectives try to “profile” serial killers and other criminals, astronomers are trying to determine what type of star system will explode as a supernova. While criminals can sometimes be caught or rehabilitated before they do the crime, supernovae, well, there’s no stopping them. But there’s the potential of learning a great deal in both astronomy and cosmology by theorizing about potential stellar explosions. At the American Astronomical Society meeting last week, Professor Bradley E. Schaefer of Louisiana State University, Baton Rouge, discussed how searching through old astronomical archives can produce unique and front-line science about supernovae – as well as providing information about dark energy — in ways that no combination of modern telescopes can provide. Additionally, Schaefer said amateur astronomers can help in the search, too.

Schaefer has been studying archived data back to 1890. “Archival data is the only way to see the long-term behavior of stars, unless you want to keep watch nightly for the next century, and this is central to many front-line astronomy questions,” he said.

Bradley E. Schaefer of Louisiana State University, Baton Rouge

The main question Schaefer is trying answer is what stars are progenitors for type Ia supernovae. Astronomers have been trying to track down this mystery for over 40 years.

Type Ia supernovae are remarkably bright but also remarkably uniform in their brightness, and therefore are regarded as the best astronomical “standard candles” for measurement across cosmological distances. Type Ia supernovae are also key to the search for dark energy. These blasts have been used as distance markers for measuring how fast the Universe is expanding.

However, a potential problem is that distant supernovae might be different from nearby events, thus confounding the measures. Schaefer said the only way to solve this problem is to identify the type of stars that explode as Type Ia supernovae so that corrections can be calculated. “The upcoming big-money supernova-cosmology programs require the answer to this problem for them to achieve their goal of precision cosmology,” said Schaefer.

Supernova 1994D in the outskirts of the galaxy NGC 4526.

Many types of star systems have been proposed as being the potential supernovae, such as double white dwarf binaries which were not discovered until 1988, and symbiotic stars which are very rare. But the most promising progenitor is the recurrent novae (RN) which are usually binary systems with matter flowing off a companion star onto a white dwarf. The matter accumulates onto the white dwarf’s surface until the pressure gets high enough to trigger a thermonuclear reaction (like an H-bomb). RNs can have multiple eruptions every century (as opposed to classical novae which have only one observed eruption).

To answer the question if RN are supernova progenitors, Schaefer conducted extensive research to get RN orbital periods, accretion rates, outburst dates, eruption light curves, and the average magnitudes between outbursts.

One big question was whether there were enough RN occurrences to supply the observed rate of supernovae. Another question was if the nova eruption itself blows off more material than is accumulated between eruptions, so the white dwarf would not be gaining mass.

In looking at the old sky photos, he was able count all the discovered eruptions and measure the frequency of RN eruptions back to 1890. He could also measure the mass ejected during an eruption by measuring eclipse times on the archived photos, and then looking at the change in the orbital period across an eruption.

In doing so, Schaefer was able to answer both questions: There was enough RN occurrences to provide sources for the observed Type Ia supernovae rate. “With 10,000 recurrent novae in our Milky Way, their numbers are high enough to account for all of the Type Ia supernovae,” he said.

He also found the mass of the white dwarf is increasing and its collapse will occur within a million years or so, and cause a Type Ia supernova.

Schaefer concluded that roughly one-third of all ‘classical novae’ are really RNe with two-or-more eruptions in the last century.

With this knowledge, astronomical theorists can now perform the calculations to make subtle corrections in using supernovae to measure the Universe’s expansion, which may help the search for dark energy.

An important result from this archival search is the prediction of a RN that will erupt at any time. An RN named U Scorpii (U Sco) is ready to “blow,” and already a large worldwide collaboration (dubbed ‘USCO2009’) has been formed to make concentrated observations (in x-ray, ultraviolet, optical, and infrared wavelengths) of the upcoming event. This is the first time that a confident prediction has identified which star will go nova and which year it will blow up in.

During this search Schaefer also discovered one new RN (V2487 Oph), six new eruptions, five orbital periods, and two mysterious sudden drops in brightness during eruptions.

Another discovery is that the nova discovery efficiency is “horrifyingly low,” Schaefer said, being typically 4%. That is, only 1-out-of-25 novae are ever spotted. Schaefer said this is an obvious opportunity for amateur astronomers to use digital cameras to monitor the sky and discover all the missing eruptions.

Photo archive at Harvard. Credit: Ashley Pagnotta

Schaefer used archives from around the world, with the two primary archives being the Harvard College Observatory in Boston, Massachusetts and at the headquarters of the American Association of Variable Star Observers (AAVSO) in Cambridge, Massachusetts. Harvard has a collection of half-a-million old sky photos covering the entire sky with 1000-3000 pictures of each star going back to 1890. The AAVSO is the clearinghouse for countless measures of star brightness by many thousands of amateurs worldwide from 1911 to present.

Source: Louisiana State University, AAS meeting press conference

January 12, 2009April 26, 2016 by Nancy Atkinson

Watch the New Moon Rover in Action

Small Pressurized Rover prototype. Credit: NASA

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The prototype for NASA’s new moon buggy will be part of the inauguration day parade on January 20 when Barack Obama becomes the new president of the US. The space agency is hoping the new president — and the rest of the viewing audience — will be impressed with the new concept for roving across the lunar surface. At the parade down Pennsylvania Avenue in Washington D.C., astronaut Mike Gerhardt will show off the rover’s capabilities of gliding smoothly, pirouetting and walking like a crab. Last Friday, NASA had a “test run” of the parade, showcasing the rover in a demonstration at Johnson Space Center in Houston.
Watch a video from the Houston Chronicle to see the rover in action. Reportedly, the rover will bring up the rear of the parade and hopefully provide a lasting impression on the new president. Just what can this rover do?

In October 2008, NASA tested the rover and several other new concepts in a desert in Arizona (see related article.) The Small Pressurized Rover, has a module on top of a rover chassis where the crew can sit inside in a shirt-sleeves environment as they drive the vehicle. The wide windows provide a full view for the astronauts, making unobstructed observations easy from inside the rover. NASA is thinking the SPR could be the astronauts’ main mode of transportation on the Moon, and could also allow them the flexibility to work inside of it without the restrictions imposed by spacesuits.

The SPR during the October desert test. Credit: NASA

The adaptable vehicle features pivoting wheels that enable crab style movement to help the rover maneuver through difficult spots. Early concepts provide an exercise ergometer that allow crews to exercise while driving and simultaneously charge the vehicle’s batteries. The rover provides spacesuits, easily accessible from inside the rover whenever the astronauts need to get out of the rover.

Top speed is 15 mph, but engineers said it outpaced Hummers, trucks and Jeeps as it crossed lava flows in the Arizona desert.

According to the Houston Chronicle, at the end of the parade when the rover reaches President Barack Obama’s box, Gernhardt will stop the rover, and he and astronaut Rex Walheim, one of two people in white spacesuits attached to the rear of the buggy, will step away from the rover.

Then, carrying an American flag, he’ll stride several paces toward Obama, halt and salute the new president, ending the parade.

Said Walheim: “I hope he sees that NASA is looking forward, that we have some really exciting ideas on how to handle lunar exploration. I think he may get excited about it, too.”

Source: Houston Chronicle