NASA’s Chandra X-ray Observatory has discovered an extraordinary outburst by a black hole in the spiral galaxy M83, located about 15 million light years from Earth. Using Chandra, astronomers found a new ultraluminous X-ray source, or
ULX. These objects give off more X-rays than most normal binary systems in which a companion star is in orbit around a neutron star or black hole.
This spectacular edge-on galaxy, called ESO 243-49, is home to an intermediate-mass black hole that may have been purloined from a cannibalised dwarf galaxy. The black hole, with an estimated mass of 50 million Suns, lies above the galactic plane. This is an unlikely place for such a massive back hole to exist, unless it belonged to a small galaxy that was gravitationally torn apart by ESO 243-49.
Astronomers using ESO’s Very Large Telescope have discovered a gas cloud with several times the mass of the Earth accelerating fast towards the black hole at the centre of the Milky Way. This is the first time ever that the approach of such a doomed cloud to a supermassive black hole has been observed. The results will be published in the 5 January 2012 issue of the journal Nature.
In a paper to be published in the Astrophysical Journal, available online now here, astronomers re-examine an old friend called SS433. As the authors put it “SS 433 has been studied for about 30 years since its discovery, the identification of the compact object, the most fundamental issue to understand this system, has remained unsolved.” With the help of the Subaru and Gemini satellites, these astronomers believe that they have better constrained the mass of SS433 to be between 1.9 and 4.9 solar masses. Nonetheless, these astronomers hedge their bets and still won’t state definitively that SS433 is indeed a black hole. And so the SS433 saga continues.
In a paper to be published in the Astrophysical Journal, available online now here, astronomers utilizing ultraviolet spectral data from the Hubble Space Telescope (HST), estimate the mass of the famous x-ray source known as Cygnus X-1 and its companion star HD 226868. The unseen companion of HD 226868 is estimated to be 11 times more massive than the Sun, and has long been suspected of being a black hole. HD 226868 is itself very massive, on the order of 23 times the mass of the Sun, and orbits the unseen companion every 5.6 days.
I’ve mentioned SS433 on this blog before, and once again now. In a paper to be published in the Monthly Notices of the Royal Academy of Sciences, astronomers have re-examined a star known as SS433. In this paper, astronomers utilize data accumulated from 2003 through 2008 from the observations made by the European Space Agency INTEGRAL (The International Gamma-Ray Astrophysics Laboratory) mission. The latest observations lead astronomers to the conclusion that SS433 is indeed a black hole in our galaxy, sometimes referred to as a microquasar. As I’ve said before, there is a superb book about SS433 written for a general audience by David H. Clark, called “The Quest for SS433,” which he called “the discovery of the astronomical phenomenon of the century.” We are still learning about it in this century. Learn the most recent information about SS433 from this pre-print online here.
Years ago, in 1986, there was a popular book written by astronomer David Clark, called “Quest for SS433.” I recall that I was most interested in the book because my mentor in astronomy (Barry Geldzahler), was mentioned in the book. The star system designated as SS433 is a very unusual star system, a binary system with a neutron star or black hole as one of the stars, and an A-type star as its companion. SS433, estimated to be about 18,000 light years distant from us, is considered by some to be the first so-called microquasar discovered. The quest to comprehend the nature of SS433 continues today. In a paper to be published in the Monthly Notices of the Royal Academy of Sciences, online now at http://xxx.lanl.gov/PS_cache/arxiv/pdf/0901/0901.2463v1.pdf Russian astronomers attempt to duplicate the x-ray spectrum of SS433 using a model they developed. If you are inclined to learn more about SS433 and a search for gamma-rays associated with the star system, you may find an old article I co-authored online at http://articles.adsabs.harvard.edu/full/1994ApJ…420..655G
Speaking of gamma-ray bursts, short-hard gamma-ray bursts are believed to be generated by the merger of black holes and neutron stars. Yesterday, astronomers released results of their simulations of such mergers, including the effects that black hole spin would have on the merger. See their pre-published results at http://xxx.lanl.gov/PS_cache/arxiv/pdf/0812/0812.2245v1.pdf
And you thought you had a weight problem? In a paper to be published in the Monthly Notices of the Royal Academy of Sciences, scientists utilizing the European Southern Observatory (ESO) Very Large Telescope announced the latest calculations for the mass of the black hole at the center of a galaxy called Centaurus A. This galaxy is estimated to be approximately 14 million light years distant, which nonetheless makes it one of the nearest radio galaxies known. It’s well known for its dusty central disk region, and is believed to be a result of a collision of galaxies. Of course, when galaxies collide that doesn’t mean that any of their stars actually collide, as there is so much space between the stars in galaxies. Anyhow, the mass of the black hole is estimated to be about 55 million times the mass of our own Sun. To learn more about these latest mass determinations read online their article at http://xxx.lanl.gov/PS_cache/arxiv/pdf/0812/0812.1000v1.pdf