X-ray echoes map the distance to a neutron star
This article, X-ray echoes map the distance to a neutron star, originally appeared on CNET.com.
NASA/CXC/U. Wisconsin/S. Heinz
This is not a crazy space rainbow. It doesn't lead to a pot of gold. This is, in fact, shimmering light echoes caused by X-rays, and it leads to the location of a neutron star.
They come from a specific neutron star called Circinus X-1, a binary star system on the galactic plane. The system consists of a neutron star -- a collapsed giant star post-supernova on its way to becoming a black hole -- in orbit around another supermassive star, which isn't so unusual. What is unusual is that the neutron star exhibits X-ray jets normally only found in black holes.
It is these highly unusual jets that have allowed astronomers using NASA's Chandra X-ray Observatory to pinpoint the star's exact location. The paper is available online via arXiv.
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"It's really hard to get accurate distance measurements in astronomy and we only have a handful of methods," said study leader Sebastian Heinz of the University of Wisconsin in Madison. "But just as bats use sonar to triangulate their location, we can use the X-rays from Circinus X-1 to figure out exactly where it is."
In late 2013, the neutron star flared with a burst of X-rays. These X-rays produced light echoes. Much like traditional sound echoes, light echoes occur when light is reflected from a source, and this reflection is seen some time after the original burst.
The X-ray burst of Circinus X-1 reflected off clouds of dust, creating a ring of echoes. Each dust cloud produced its own reflection and by comparing that data with images of dust clouds previously taken by the Mopra Telescope in Australia, scientists were able to pinpoint its location.
Using radio data to determine the distance to the different clouds, combined with the X-ray echo data, researchers were able to pinpoint Circinus X-1's location to about 30,700 light-years from Earth.
X-rays reveal hidden details of the cosmos (pictures)
For the first time since exoplanets were discovered nearly 20 years ago, X-rays have been used to picture an exoplanet passing in front of its parent star.
NASA's Chandra X-ray Observatory and the European Space Agency's XMM Newton Observatory on Monday observed the dip in X-ray intensity as the planet, HD 189733b, eclipsed its parent star in a system 63 light-years from Earth.
The X-ray image captured by Chandra, inserted in the illustration above, provides scientists a breadth of new information about the planet's properties and the environment it inhabits. The exoplanet itself cannot be seen in the Chandra image, as transits involve measuring small decreases in X-ray emission from the main star.
Launched on July 23, 1999, NASA's Chandra X-ray Observatory is a telescope specifically designed to detect X-rays from high-energy regions of the universe such as such as exploded stars, clusters of galaxies, and matter around black holes. Click through this gallery to see some of the amazing images Chandra helped capture.
Planetary nebulas form when a red star like the sun becomes a red giant and sheds its outer layers. This composite image of planetary nebula NGC 2392, which is located about 4,2000 light-years from Earth, shows X-ray data from Chandra in purple and data from the Hubble Space Telescope in red, green, and blue. The X-ray data from Chandra shows the location of million-degree gas near the center of the planetary nebula, while Hubble captured the intricate pattern of the outer layers of the star that have been shed.
By combining X-ray, optical, and radio data, astronomers were able to get a full picture of a giant black hole in the center of the galaxy 4C+29.30. The X-ray data from Chandra, shown in blue, near the center of the image marks a pool of million-degree gas around the black hole. Optical light obtained with Hubble is shown in gold, and radio waves from the NSF's Very Large Array are in pink.
An image of SN 1006, captured from multiple pointings of Chandra’s field-of-view between July 2000 and 2012, shows the debris field that was created when a white dwarf star exploded, sending its material hurtling into space. In the image, low-, medium-, and high-energy X-rays are colored red, green, and blue respectively.
Chandra observations of the Small Magellanic Cloud, one of the closest galaxies to the Milky Way, resulted in the first detection of X-ray emission from young stars outside our galaxy with masses similar to our Sun. In this composite image Chandra data is shown in purple, optical data from the Hubble is shown in blue, and infrared data from the Spitzer Space Telescope is shown in red.
The remnant of Kepler’s supernova, the famous explosion discovered by German astronomer Johannes Kepler in 1604, is seen in this composite image. The low-, intermediate-, and high-energy X-rays captured by Chandra are shown in red, green, and blue respectively. The star field is from the Digitized Sky Survey.
This image was compiled from a long Chandra observation of a neutron star in 47 Tucanae, a globular cluster about 15,000 light-years away. Neutron stars, the ultra-dense cores left behind after a star collapses, contain the densest matter in the universe outside of a black hole.
W49B, a distorted supernova remnant, may contain one of the youngest black holes in the Milky Way galaxy. This composite image shows X-rays from Chandra in blue and green, radio data from the NSF's VLA in pink, and infrared data from Caltech's Palomar Observatory in yellow.
DEM L50 is a "supperbubble" in the Large Magellanic Cloud about 160,000 light-years from Earth. This composite image shows X-rays from Chandra in pink and optical data from the Magellanic Cloud Emission Line Survey in red, green, and blue.
"We like to call this system the 'Lord of the Rings,' but this one has nothing to do with Sauron," said co-author Michael Burton of the University of New South Wales in Sydney, Australia. "The beautiful match between the Chandra X-ray rings and the Mopra radio images of the different clouds is really a first in astronomy."
The finding has allowed the team to settle the dispute about Circinus X-1's location from conflicting previous studies, but the results also mean several interesting things about the binary system. For example, Circinus X-1 is much brighter in X-rays and other types of light than previously thought -- in fact, its brightness is more in keeping with a black hole than a neutron star.
The aforementioned X-ray jets have also been confirmed to be very black-hole like. The researchers determined that the high-energy particle jets are travelling at at least 99.9 percent of the speed of light -- speeds usually only seen in black holes.
"Circinus X-1 acts in some ways like a neutron star and in some like a black hole," said co-author Catherine Braiding of the University of New South Wales. "It's extremely unusual to find an object that has such a blend of these properties."
