Category: Astronomy

Astronomers have found the remains of the youngest supernova, or exploded star, in the Milky Way Galaxy. The supernova occurred in 1868, but was hidden behind a thick veil of gas and dust. Using the Very Large Array (VLA) and NASA’s Chandra X-Ray Observatory, which could peer through the veil, astronomers have now found “G1.9+0.3,” the first example of what scientists believe are a “missing population” of young supernova remnants. This is NASA’s long awaited announcement, and astronomers have been searching for over 50 years for this type of young supernova.

From observing supernovae in other galaxies, astronomers estimate that about three such stellar explosions should occur in our Milky Way every century. However, the most recent one known until now occurred around 1680, creating the remnant called Cassiopeia A. The newly-discovered object is the remnant of an explosion only about 140 years ago.

“It’s great to finally track one of them down,” said David Green of the University of Cambridge in the UK, who led the VLA study.

Supernovas mark the violent death of a star, and release tremendous amounts of energy and spew heavy elements such as calcium and iron into interstellar space. This seeds the clouds of gas and dust from which new stars and planets are formed.

The lack of evidence for young supernova remnants in the Milky Way had caused astronomers to wonder if our Galaxy, which appears otherwise normal, differed in some unknown way from others, or if our understanding of the relationship between supernovae and other galactic processes was in error.

Cassiopeia A supernova remnant — from the year 1680.

The astronomers made their discovery by measuring the expansion of the debris from the star’s explosion. They did this by comparing images of G1.9+0.3, made more than two decades apart.

In 1985, astronomers led by Green observed G1.9+0.3 with the VLA and identified it as a supernova remnant. At that time, they estimated its age as between 400 and 1,000 years. It is near the center of our Galaxy, roughly 25,000 light-years from Earth.

In 2007, another team of astronomers, led by Stephen Reynolds of North Carolina State University, observed the object with the Chandra X-Ray Observatory. To their surprise, their image showed
the object to be about 16 percent larger than in the 1985 VLA image.

“This is a huge difference. It means the explosion debris is expanding very quickly, which in turn means the object is much younger than we originally thought,” Reynolds explained.

However, this expansion measurement came from comparing a radio image to an X-ray image.

To make an “apples to apples” comparison, the scientists sought and were quickly granted observing time on the VLA which confirmed the supernova remnant’s rapid expansion.

The object already has provided surprises. The velocities of its explosion debris and extreme energies of its particles are unprecedented. “No other object in the Galaxy has properties like this,” said Reynolds. “Finding G1.9+0.3 is extremely important for learning more about how some stars explode and what happens in the aftermath.”

Original News Sources: Chandra site , National Radio Astronomy Observatory

You can breathe easily. The Moon is slowly receding away from the Earth at a rate of 3.7 cm/year (1.5 in/yr). But the Martians aren’t so lucky. Their moon Phobos is known to be doing exactly the opposite. It’s spiraling inward, and in the distant future it will crash into the surface of Mars. Researchers originally thought that Phobos has about 50 million years to go, but an Indian researcher has re-run the calculations and thinks Phobos only has about a quarter of that time to live.

It was originally believed that Phobos would take about 50 million years to crash into the surface of Mars, but according to Bijay Kumar Sharma, an Assistant Professor at the National Institute of Technology in Bihar, India, it might happen much more quickly. Dr. Sharma has revised the calculations for Phobos’ destruction in his new paper, Theoretical Formulation of the Phobos, moon of Mars, rate of altitudinal loss.

According to Sharma, Phobos will actually be destroyed about 10.4 million years from now, and not the 50 million years the researchers had previously calculated.

Phobos is believed to be an asteroid that Mars captured early on in its history. it’s one of the least-reflective objects in the Solar System, and thought to be similar to a D-type asteroid. It currently orbits Mars at an altitude of about 9,380 km (or about 6,000 km above the Martian surface).

Why does the Earth’s moon spiral outward, while Phobos is spiraling inward to Mars?

The Moon formed billions of years ago when a Mars-sized object crashed into Earth and sprayed material into orbit. This material pulled back together from mutual gravity to form the Moon, and this debris received a gravitational slingshot from the Earth.

They key is that the material was tossed into a high enough orbit, above what’s known as the synchronous orbit. This is where the Moon completes an orbit slower than the Earth takes to rotate once. Since the Moon ended up higher than this orbit, it’s spiraling outward. If its orbit was less than the length of a day, it would spiral inward.

And this is what has happened to Phobos. It orbits below this synchronous orbit, where it completes an orbit around Mars faster than the planet itself turns. It’s spiraling inward instead of outward.

Once Phobos gets down to an altitude of only 7000 km above the center of Mars (or 3,620 km above its surface), it will enter what’s known as the Roche limit. At this point, the tidal forces of Mars will tear Phobos apart, turning it into a ring that will continue to spiral into Mars. According to Dr. Sharma, this will happen in only 7.6 million years from now.

To know exactly how long Phobos has to live, Dr. Sharma suggests that a mission should be sent to Phobos to land on its surface and then use radar to measure the changing distance to Mars.

Original Source: Arxiv

It would be amazing to think that anything could have survived the fiery destruction of the space shuttle Columbia, which broke up above Texas on February 1st, 2003, killing all 7 astronauts. Amazingly, tiny worms survived the break up and crash. And now, data recovery experts announced they were able to salvage scientific data from a charred hard drive.

The announcement was made last week by data recovery company Kroll Ontrack Inc. When they received a smashed up hard drive from NASA, it just looked like a hunk of metal. But after painstaking work, they were able to recover 99% of the information stored on the hard drive.

The hard drive was part of study of the critical viscosity of xenon gas. As the data were being gathered on board Columbia as part of its mission, they were being transmitted back down to Earth. They had only transmitted part of the data, enough to tell researchers that the experiment was working. They were going to wait until Columbia landed to get the rest. Of course, Columbia never landed.

What NASA sent to Kroll Ontrack was almost unrecognizable as a hard drive. Jon Edwards, a senior clean room engineer at the company said that the circuit board on the drive was burned beyond recognition and that all its components had fallen off. Every piece of plastic on the 400 MB Seagate hard drive had melted, and the chips were burned.

Unfortunately, two other drives that crashed with Columbia were so damaged that no data could could be extracted from them. One of the Seagate’s keys to its survival is that it was actually quite old and had a much lower data capacity. The 400 MB drive was about 8 years old in 2003. It had much more fault tolerance and durability that current hard drive capacity.

Engineers were able to remove the hard drive platters from the destroyed drive and transfer them to a new drive. From there they were able to reconstruct 99% of the data.

Original Source: Scientific American

Over the past few weeks we’ve taken a look at some pretty incredible regions of space through astrophotography – Wolf Rayet stars, Thackeray’s Globules, tidal interactions and even giant dust clouds bursting with star birth. This time, let’s take a look at something so obscure that it might even be the first time that it’s been photographed…

What you’re looking at van den Bergh 149 (RA 22 09 08.5 Dec +72 53 05), van den Bergh 150 (RA 22 09 40.1 Dec +73 23 27) , and dark nebula LDN1235; Cepheus. According to image author, Tom Davis: “These two reflection nebulae are rarely imaged and this image may well be a premiere for amateur astroimaging. vdB 149 is the blue reflection nebula on the center left; vdB150 the center right. The darker nebula just “above” vdB150 is Lynds Dark Nebula 1235. It is likely an Extended Red Emission nebula (ERE). These ERE are galactic dark nebulae at high latitudes that become visible through illumination by the interstellar radiation field. ERE is a dust-luminescence process, which appears in a broad band extending in wavelength across the R-band (Schedler). This image is a composite-hybrid between two images taken with telescopes of different focal lengths. These nebulae have very low surface brightness and pose a significant challenge in imaging them. There are even fainter wisps of dust that make up the sky background. These small clouds are yet uncataloged as far as I can find through research. ”

In 1966, Sidney Van Den Bergh produced his own catalog of bright nebula with embedded stars. It contains information for “all BD and CD stars north of -33 deg which are surrounded by reflection nebulosity visible on both the blue and red prints of the Palomar Sky Survey. The nearer reflection nebulae lie predominantly along Gould’s Belt, whereas the more distant ones are concentrated to the galactic plane. The data outline 13 associations of reflection nebulae, some of which coincide with known OB or T associations. Attention is drawn to the fact that most reflection nebulae are illuminated by the integrated light of the Milky Way. The integrated radiation will be more intense above and below the galactic plane then in the galactic plane where the nuclear bulge of the Galaxy and most of the disk are obscured by interstellar absorption.”

Ninth magnitude vdB 149 first appeared in scientific literature around 1957 during a search for cepheids in galactic clusters done by Sidney Van Den Berg. Later, in 1960, it was also picked up by Halton Arp and more formally in 1966 when Van Den Berg did his “Study of Reflection Nebulae” utilizing the Palomar Sky Survey plates. It is also the 159th reflection nebula corresponding to HD 224403 (GLON=116.6, GLAT=-00.22) is introduced by R. Racine in his study of stars in Reflection Nebulae in 1968 where photometric and spectroscopic observations were done for fifteen distinct regions.

However, 8.4 magnitude vdB 150 holds a much more colorful history, having been noted in 1918 by Annie Jump Cannon and Edward Pickering. Annie picked it up again in 1925 during the extended Henry Draper Catalog Study and again in 1949 in a commemorative work done with Walton Mayall. From there, it laid dormant until 1991 and 1995 when revisited again by the Astrographic Catalogue for spectral type, proper motion and position. It holds its place in basic data as HD 210806 — Star in Nebula.

Like the Van Den Bergh catalogs of bright nebula where curtains of gas and dust conjoin with stars, the Lynds Dark Nebula catalog was developed in much the same way – compiled from studies of the red and blue prints from the Palomar Sky Survey. “The range in declination is from +90 to -33 degrees. A cloud had to be visible on both the red and the blue photographs in order to be recorded. It is therefore very probable that the more tenuous clouds which may be transparent in the red are not included herein. Lynds states that it was often difficult to detect a cloud that absorbed less than 0.75 magnitudes. Many of the small dark nebulae termed `Bok Globules‘ are not included in this catalog because they are apparent as dark objects projected against the bright background of an emission nebulosity: only objects which, on the basis of stellar density fluctuations, indicated the presence of absorption are contained here.”

Do these regions meet and produce new anomalies which need further study? I’d say that’s affirmative. It’s a well known fact LDN 1235 contains a variable star and that Lynd’s dark nebulae have differing turbulent velocities. There are areas where the opacity is weak and may very well have reached excitation temperatures – the density decreases and the temperature increases along the outward edges. Although it’s only conjecture on my part, I’d say that photographic studies like those done by Tom Davis are extremely important in the long term. They provide photographic record of changes not captured by professional observatories and will eventually become a source of future reference.

One that both amateur and professionals can study and enjoy…

This week’s awesome image is done by MRO member, Tom Davis. They were taken with an Astro Systeme Austria N12 f/3.5 Astrograph (LUM) and Takahashi FSQ-106 f/5 Astrograph (RGB) KAI-11000M – Total Exposure 10.6+ hours; LRGB 260:120:120:120 minutes, unbinned – April-May 2008; Inkom, ID, USA.