NASA | MSFC | SAO | Chandra X-ray Observatory | 2015 Jun 23
[c][imghover=http://www.chandra.si.edu/photo/2015/ci ... x1_w11.jpg]http://www.chandra.si.edu/photo/2015/ci ... el_525.jpg[/imghover]Credit: X-ray: NASA/CXC/Univ of Wisconsin-Madison/S. Heinz et al; Optical: DSS[hr][/hr][/c]Data from NASA's Chandra X-ray Observatory has helped provide a rare opportunity to determine the distance to an object on the other side of the Milky Way galaxy, as described in our latest press release.
The object is Circinus X-1, containing a neutron star - the collapsed core left behind after a star exploded - in orbit with a massive star. The Chandra data reveal a set of four rings that appear as circles around Circinus X-1. These rings can be seen in the composite image where X-rays from Chandra are red, green, and blue corresponding to low, medium, and high-energy X-rays respectively, which have been combined with a view in visible light from the Digitized Sky Survey. The sharp edges are caused by the large size of the X-ray rings compared to the relatively small field-of-view of the Chandra detectors, providing only partial coverage.
What are these rings and what information do they provide? These rings are light echoes, similar to sound echoes that we may experience here on Earth. Instead of sound waves bouncing off a canyon wall, the echoes around Circinus X-1 are produced when a burst of X-rays from the star system ricochet off of clouds of dust between Circinus X-1 and Earth. ...
By combining the light echoes that Chandra detects with radio data from the Mopra radio telescope in Australia, which determined the distance to the intervening clouds, astronomers can estimate the distance to Circinus X-1 using relatively simple geometry. The light echo method generates a distance of 30,700 light years. The observation thus settles a large difference amongst previous results, one similar to this work and one indicating a much smaller distance of about 13,000 light years. ...
Neutron star’s echoes give astronomers a new measuring stick
University of Wisconsin—Madison | 2015 Jun 23
Lord of the Rings: A Kinematic Distance to Circinus X-1 from a Giant X-Ray Light Echo - Sebastian Heinz et al
- Astrophysical Journal 806(2) 265 (2015 Jun 20) DOI: 10.1088/0004-637X/806/2/265
arXiv.org > astro-ph > arXiv:1506.06142 > 19 Jun 2015
- Astrophysical Journal 779(2) 171 (2013 Dec 20) DOI: 10.1088/0004-637X/779/2/171
arXiv.org > astro-ph > arXiv:1312.0632 > 02 Dec 2013
http://asterisk.apod.com/viewtopic.php?t=32578
