Blasted Star Blossoms like a Cosmic Flower

Because the wreckage fields of exploded stars, well-known as supernova remnants, are very hot, energetic, and glow brightly in X-ray light, NASA's Chandra X-ray Observatory has demonstrated to be a valuable tool in exploring them. The supernova leftover called G299.2-2.9 (or G299 for short) is situated within our Milky Way galaxy, but Chandra's new picture of it is reminiscent of a beautiful flower here on Earth. G299 was left over by a specific class of supernovas called Type Ia. Astrophysicists think that a Type Ia supernova is a thermonuclear blast - comprising the fusion of elements and release of vast amounts of energy - of a white dwarf star in a tight orbit with a neighbouring star. If the white dwarf's partner is a usual, Sun-like star, the white dwarf can turn out to be unstable and detonate as it draws material from its companion. Otherwise, the white dwarf is in orbit with another white dwarf, the two may combine and can initiate a blast.

Irrespective of their triggering mechanism, Type Ia supernovas have long been well-known to be constant in their extreme brightness, typically outshining the entire galaxy where they are present. This is important as researchers use these objects as cosmic mileposts, letting them to precisely measure the distances of galaxies billions of light years away, and to conclude the rate of expansion of the Cosmos.

Traditional theoretical models of Type Ia supernovas usually forecast that these explosions would be symmetric, creating a near faultless sphere as they expand. These models have been reinforced by results showing that leftovers of Type Ia supernovas are more symmetric than leftovers of supernovas comprising the collapse of massive stars.

Though, astrophysicists are finding that some Type Ia supernova explosions may not be as symmetric as formerly believed. G299 could be an example of such an "unusual" Type Ia supernova. Using a long observation from Chandra, scientists found the shell of debris from the exploded star is growing differently in different directions.

In this new Chandra image, red, green, and blue characterise low, medium, and high-energy X-rays, respectively, perceived by the telescope. The medium energy X-rays include emission from iron and the hard-energy X-rays include emission from silicon and sulfur. The X-ray data have been joint with infrared data from ground-based 2MASS study that displays the stars in the field of view.

By performing a thorough study of the X-rays, scientists found numerous clear examples of asymmetry in G299. For example, the ratio between the amounts of iron and silicon in the part of the remnant just above the center is bigger than in the part of the leftovers just below the center. This difference can be perceived in the greener color of the upper region compared to the bluer color of the lower region. Also, there is a intensely elongated portion of the remnant spreading to the right. In this region, the comparative amount of iron to silicon is alike to that present in the southern region of the remnant.

The patterns seen in the Chandra data proposes that a very lopsided blast may have created this Type Ia supernova. It might also be that the leftover has been expanding into an environment where the medium it met was uneven. Irrespective of the eventual explanation, observations of G299 and others like it are showing astrophysicists just how varied such beautiful cosmic flowers can be.

A paper describing these outcomes was issued in the September 1st, 2014 issue of The Astrophysical Journal, and is accessible online. The writers are Seth Post and Sangwook Park from the University of Texas at Arlington in Texas; Carles Badenes from the University of Pittsburgh, in Pittsburgh, Pennsylvania; David Burrows from Pennsylvania State University in University Park, Pennsylvania; John Hughes from Rutgers University in Piscataway, New Jersey; Jae-Joon Lee from the Korea Astronomy and Space Science Institute; Koji Mori from the University of Miyazaki in Japan and Patrick Slane from the Harvard-Smithsonian Center of Astrophysics in Cambridge, Massachusetts.

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.




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