Viktor Hambardzumyan on Star Formation

Viktor Amazaspovich Ambartsumian, also known as Viktor Hambardzumyan, was a scientist that most people have probably never heard of. The old Great Soviet Encyclopedia lauded his work in the former USSR, though some official Soviet documents had a tendency to blend science and politics. Nevertheless, his work on theoretical astrophysics should not be ignored.

In 1946, Ambartsumian founded the Biurakan Astrophysical Observatory of the Academy of Sciences. His work often dealt with theories that attempted to quantify the emissions of gaseous nebulae. He proposed a particular method used to calculate the amount of mass that nova stars eject, as well as the outflow of star surfaces. The individual stars he studied were not regular stationary orbital bodies. These theories revolutionized the way in which people thought about the way stars exist.

Ambartsumian’s theories often involved the concept of discrete dark nebulae. According to his research, the absorption of light in interstellar deep space wasn’t caused by the attenuation of traveling along the absent medium. Instead, he believed discrete dark nebulae caused the phenomenon.

Such nebulae make the direct observation of many phenomena quite difficult. In fact, things that they obscure can only be viewed with radio or infrared astronomy equipment. That being said, they also call into question the nature of the universe. Scientists are still learning the science behind star formation but I’m sure our progress thus far would certainly make Ambartsumian proud.

VISTA Views a Vast Ball of Stars

Globular clusters are held together in a tight spherical shape by gravity. In Messier 55, the stars certainly do keep close company: approximately one hundred thousand stars are packed within a sphere with a diameter of only about 25 times the distance between the Sun and the nearest star system, Alpha Centauri. Read More →

1000 Days of Infrared Wonders

For the last 1000 days the Infrared Array Camera (IRAC), aboard NASA’s Spitzer Space Telescope, has been operating continuously to probe the universe from its most distant regions to our local solar neighborhood. The IRAC “warm” program began once Spitzer used up its liquid helium coolant, thus completing its “cold” mission. To commemorate 1000 days of infrared wonders, the program is releasing a gallery of the 10 best IRAC images. Read More →

Let’s Explore ‘Light Echoes’ in Space

Astronomers have learned a great many things via the study of variable stars throughout the years. Perhaps some of the most exciting phenomena studied by scientists involve those which emit bright pulses of light during eruptive or disruptive events (such as novae or supernovae). Because of the light emitted, there is actually a brief period of time during which actual information about these rare events may be studied. Read More →

How Black Holes Grow

A study (referenced below) led by a University of Utah astrophysicist found a new explanation for the growth of supermassive black holes in the center of most galaxies: they repeatedly capture and swallow single stars from pairs of stars that wander too close.

Using new calculations and previous observations of our own Milky Way and other galaxies, “we found black holes grow enormously as a result of sucking in captured binary star partners,” says physics and astronomy Professor Ben Bromley, lead author of the study, which is set for online publication April 2 in Astrophysical Journal Letters. Read More →

Large Synoptic Survey Telescope (LSST) Overview

At its completion in 2016, the Large Synoptic Survey Telescope (LSST) will provide the largest ever survey of the night sky. It will deliver 30 terabytes of data each night. LSST will consist of an 8.4 meter telescope and the 3.2 billion pixel camera. Astronomers hope the Large Synoptic Survey Telescope will deliver 5.6 million 15 second images over its ten year lifetime. The images will then be cataloged and made available for viewing by both the public and researchers.  Astronomers hope these images will allow them to create a 3D map of the universe. In addition, they hope it will greatly increase their understanding of dark matter and dark energy.

The location was carefully chosen after much debate. The location has an altitude of 2,715 meters above sea level. The mountain is known to have some of the darkest skies in the world. The area has very little rainfall and one of the most stable environments on Earth. A stable atmosphere with a large number of clear nights will greatly assist astronomers in collecting data. The Cerro Pachon Mountain is currently home to the Gemini South Telescope and the Southern Astrophysical Research Telescope. The planned location is just northwest of the Cerro Tololo Inter-American Observatory.

Be back tomorrow with a little information on another amazing endeavor – ESA’s Gaia project!

Reference:

The New Sky | LSST. (n.d.). Large Synoptic Survey Telescope. Retrieved March 27, 2012, from http://www.lsst.org/lsst/

Edwin Hubble – Discoverer of Galaxies

Edwin Hubble was born in a small town in Missouri in 1889. From a young age, he developed an interest in science and astronomy and desperately wished to make astronomy his career.

Hubble graduated from college with a bachelor’s degree in science and was subsequently accepted as a Rhodes Scholar to study at Oxford University. Surprisingly, his studies at Oxford were in law rather than astronomy.

Upon graduating, he became a practicing lawyer in Louisville, Kentucky. He also worked for a time as a school teacher but he wasn’t happy with his career path. He returned to school and earned his doctorate in astronomy a short time later.

When Hubble began his career, the standard theory held that the Milky Way galaxy was the entirety of the universe. Through nightly observation, and the use of astronomic photography, Hubble proved that objects in the constellation Andromeda were at least one million light years away. In other words, there was more to the universe than the Milky Way. The universe was filled with galaxies!

Hubble’s other great breakthrough involved the discovery of an approximate relationship between the redshifts of galaxies and the distances to them using a formulation known as Hubble’s law. Through these measurements, a strong case is made for the expansion of the universe as well as supporting the Big Bang theory.

Edwin Hubble passed away in 1953. The Hubble Space Telescope (shown below) is named in his honor. Using data from the Hubble Space Telescope, astronomers hope to be able to figure out the likely fate of our universe: will it expand forever, or will the expansion reverse and cause the universe to collapse back into another Big Bang? It would be interesting to get Hubble’s take on things given the knowledge we know today.

Image Credit: NASA

Reference:

http://www.spacetelescope.org/about/history/the_man_behind_the_name/
http://www.edwinhubble.com/hubble_bio_001.htm

Astronomers discover rare ’emerald-cut’ galaxy

An international team of astronomers has discovered a rare square galaxy with a striking resemblance to an emerald cut diamond.

The astronomers – from Australia, Germany, Switzerland and Finland – discovered the rectangular shaped galaxy within a group of 250 galaxies some 70 million light years away.

“In the Universe around us, most galaxies exist in one of three forms: spheroidal, disc-like, or lumpy and irregular in appearance,” said Associate Professor Alister Graham from Swinburne University of Technology.

He said the rare rectangular-shaped galaxy was a very unusual object. “It’s one of those things that just makes you smile because it shouldn’t exist, or rather you don’t expect it to exist.

“It’s a little like the precarious Leaning Tower of Pisa or the discovery of some exotic new species which at first glance appears to defy the laws of nature.”
The unusually shaped galaxy was detected in a wide field-of-view image taken with the Japanese Subaru Telescope for an unrelated program by Swinburne astrophysicist Dr Lee Spitler.

The astronomers suspect it is unlikely that this galaxy is shaped like a cube. Instead, they believe that it may resemble an inflated disc seen side on, like a short cylinder.

Support for this scenario comes from observations with the giant Keck Telescope in Hawaii, which revealed a rapidly spinning, thin disc with a side on orientation lurking at the centre of the galaxy. The outermost measured edge of this galactic disc is rotating at a speed in excess of 100,000 kilometres per hour.

“One possibility is that the galaxy may have formed out of the collision of two spiral galaxies,” said Swinburne’s Professor Duncan Forbes, co author of the research.

“While the pre-existing stars from the initial galaxies were strewn to large orbits creating the emerald cut shape, the gas sank to the mid plane where it condensed to form new stars and the disc that we have observed.”

Despite its apparent uniqueness, partly due to its chance orientation, the astronomers have managed to glean useful information for modelling other galaxies.

While the outer boxy shape is somewhat reminiscent of galaxy merger simulations which don’t involve the production of new stars, the disc-like structure is comparable with merger simulations involving star formation.

“This highlights the importance of combining lessons learned from both types of past simulation for better understanding galaxy evolution in the future,” said Associate Professor Graham.

“One of the reasons this emerald cut galaxy was hard to find is due to its dwarf-like status: it has 50 times less stars than our own Milky Way galaxy, plus its distance from us is equivalent to that spanned by 700 Milky Way galaxies placed end-to-end.

“Curiously, if the orientation was just right, when our own disc-shaped galaxy collides with the disc-shaped Andromeda galaxy about three billion years from now we may find ourselves the inhabitants of a square looking galaxy.”

Source: Swinburne University of Technology

Reference:

Alister W. Graham, Lee R. Spitler, & Duncan A. Forbes (2012). LEDA 074886: A REMARKABLE RECTANGULAR-LOOKING GALAXY The Astrophysical Journal arXiv:1203.3608v1

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NuSTAR Mission Update and Overview

Image credit: NASA

On Friday NASA announced that the launch of its newest spacecraft from California will unfortunately be delayed a bit longer. Regardless, I thought I’d post about the mission as this is a project I’m eagerly awaiting. The mission, known as NuSTAR, will map areas of the Milky Way Galaxy. This particular project is one of the least expensive NASA has ever deployed. NASA has announced that launch will hopefully occur within the next two months.

NuStar Mission Overview

One mission objective is to count collapsed stars and black holes near the center of the Milky Way. Scientists also hope to get a closer look at young supernova to understand the formation process as well as  how the different elements of supernovas are created. Furthermore, the mission team hopes to develop a deeper understanding of what powers the jets of particles streaming from the largest black holes. Scientists also hope the mission will encounter a few gamma ray bursts leading to a deeper understanding of them as well.

This will be the first time the new NuSTAR telescope will be used. The folding telescope is at least 10 times stronger than previous telescopes employed on the Chandra and XMM projects. The telescope will be folded until the rocket reaches low earth orbit where it will proceed to unfold. Mission specialists say that the time the telescope takes to unfold will be the scariest aspect of the launch. This will be one of the first times that a folding telescope has been deployed in an unmanned spacecraft.

NuSTAR is a Small Explorer mission led by the California Institute of Technology and managed by NASA’s Jet Propulsion Laboratory, both in Pasadena, Calif., for NASA’s Science Mission Directorate. The spacecraft was built by Orbital Sciences Corporation, Dulles, Va. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA’s Goddard Space Flight Center in Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Calif.; and ATK Aerospace Systems, Goleta, Calif. NuSTAR will be operated by UC Berkeley, with the Italian Space Agency providing its equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University, Calif. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

The mission is expected to last two years and results will be published as they become available from this exciting project.

Right now I just hope NASA get things worked out and gets this up in the sky sooner rather than later.

http://www.nasa.gov/mission_pages/nustar/overview/index.html

Meet I Zw 18: A Dwarf Galaxy

The Center of Astrophysics of the University of Porto recently came up with an analysis that seriously calls into question the current model of galactic formation. Polychronis Papaderos represented the CAUP, and with his Swedish colleague Göran Östlin, Papderos examined data from the Hubble Space Telescope to better understand the I Zw 18 dwarf galaxy. That particular object has received a lot of attention, and it is one of the few places where star-forming activity can be readily observed.

I Zw 18 region. (Credit: Image courtesy of Centro de Astrofísica da

For a long time, astrophysicists have simply assumed that stars were emitting light from gas structures. These structures occupied the same region as the stars that were emitting the light. The research suggests that galaxies that undergo active starbursts don’t follow this rule. Instead, nebula gases might actually be emitting around half of the total light in question. Since star mass is often calculated from the galaxy’s total luminosity, the idea that nebular emissions account for so much light means that many of these calculations could be totally off. One could also surmise that since I Zw 18 is young, the galaxy is acting the way many objects did shortly after the Big Bang. Many of the stars there have been around for less than 1 billion years. It will be interesting to watch this galaxy in the years ahead.

Reference:

Papaderos, P., & Östlin, G. (2012). I Zw 18 as morphological paradigm for rapidly assembling high-galaxies Astronomy & Astrophysics, 537 DOI: 10.1051/0004-6361/201117551

Izotov, Y., Chaffee, F., Foltz, C., Thuan, T., Green, R., Papaderos, P., Fricke, K., & Guseva, N. (2001). A Spectroscopic Study of Component C and the Extended Emission around I Zw 18 The Astrophysical Journal, 560 (1), 222-235 DOI: 10.1086/322494

Image Credit: Hubble

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