Astronomy Picture of the Day – Supernova and the Unexpected Universe

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 May 31

Supernova 1994D and the Unexpected Universe
Image Credit: High-Z Supernova Search Team, HST, NASA

 

Explanation: Long ago, far away, a star exploded. Supernova 1994D, visible as the bright spot on the lower left, occurred in the outskirts of disk galaxy NGC 4526. Supernova 1994D was not of interest for how different it was, but rather for how similar it was to other supernovae. In fact, the light emitted during the weeks after its explosion caused it to be given the familiar designation of a Type Ia supernova. If all Type 1a supernovae have the same intrinsic brightness, then the dimmer a supernova appears, the farther away it must be. By calibrating a precise brightness-distance relation, astronomers are able to estimate not only the expansion rate of the universe (parameterized by the Hubble Constant), but also the geometry of the universe we live in (parameterized by Omega and Lambda). The large number and great distances to supernovae measured over the past few years, when combined with other observations, are interpreted as indicating that we live in a previously unexpected universe.

Astronomy Picture of the Day for June 21 – WR 134 Ring Nebula

Discover the cosmos!Each day a different image or photograph of our fascinating universe is  featured, along with a brief explanation written by a professional astronomer.

2012 June 21

WR 134 Ring Nebula Image 

Credit & Copyright: Don Goldman  

Explanation: Made with narrow and broad band filters, this colorful cosmic snap shot covers a field of view about the size of the full Moon within the boundaries of the constellation Cygnus. It highlights the bright edge of a ring-like nebula traced by the glow of ionized hydrogen and oxygen gas. Embedded in the region’s interstellar clouds of gas and dust, the complex, glowing arcs are sections of bubbles or shells of material swept up by the wind from Wolf-Rayet star WR 134, brightest star near the center of the frame. Distance estimates put WR 134 about 6,000 light-years away, making the frame over 50 light-years across. Shedding their outer envelopes in powerful stellar winds, massive Wolf-Rayet stars have burned through their nuclear fuel at a prodigious rate and end this final phase of massive star evolution in a spectacular supernova explosion. The stellar winds and final supernovae enrich the interstellar material with heavy elements to be incorporated in future generations of stars.

NASA Image of the Day for October 14th

Carina Nebula: 14,000+ Stars

The Carina Nebula is a star-forming region in the Sagittarius-Carina arm of the Milky Way that is 7,500 light years from Earth and the Chandra X-Ray Observatory has detected more than 14,000 stars in the region.

Chandra’s X-ray vision provides strong evidence that massive stars have self-destructed in this nearby star-forming region. Firstly, there is an observed deficit of bright X-ray sources in the area known as Trumpler 15, suggesting that some of the massive stars in this cluster were already destroyed in supernova explosions. Trumpler 15 is located in the northern part of the image and is one of ten star clusters in the Carina complex.

The detection of six possible neutron stars, the dense cores often left behind after stars explode in supernovas, provides additional evidence that supernova activity is increasing up in Carina. Previous observations had only detected one neutron star in Carina.

Image Credit: NASA/CXC/Penn State/L. Townsley et al.

Astronomy Picture of the Day for Sept. 20 – Origin of Gold

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

On the Origin of Gold
Image Credit: Dana Berry, NASA

 

Explanation: Where did the gold in your jewelry originate? No one is completely sure. The relative average abundance in our Solar System appears higher than can be made in the early universe, in stars, and even in typical supernova explosions. Some astronomers have recently suggested that neutron-rich heavy elements such as gold might be most easily made in rare neutron-rich explosions such as the collision of neutron stars. Pictured above is an artist’s illustration depicting two neutron stars spiraling in toward each other, just before they collide. Since neutron star collisions are also suggested as the origin of short duration gamma-ray bursts, it is possible that you already own a souvenir from one of the most powerful explosions in the universe.