Spitzer Spies Remnants of a Shy Star

Big stars usually aren't shy about anything, not even death. At the end of their lives, they throw explosive tantrums, called supernovae, flinging abundant amounts of hot gas and radiation into space. Remnants of this cosmic fury can last for several thousand years and be easily detected by most telescopes used by professional astronomers.

But not all stars like attention. Thirty thousand light-years away in the Cepheus constellation, astronomers think they've found a massive star whose death barely made a "peep." Remnants of this shy star's supernova would have gone completely unnoticed if the infrared eyes of NASA's Spitzer Space Telescope hadn't accidentally stumbled upon them.

"This source is really trying to avoid detection," said Dr. Patrick Morris of NASA's Herschel Science Center at the California Institute of Technology in Pasadena, Calif. He is the lead author of a paper on the discovery, which was published in the April 2006 Astrophysical Journal Letters.

What makes this lone star so unusual? Morris suspects that it sits away from the mobs of stars that occupy the main disk of our Milky Way galaxy. Our galaxy's disk is a crowded and dusty place, whereas the regions above and below are comparatively dust free. It is this dust that allows exploding stars to be readily detected. Expelled material violently collides with surrounding dust, giving off bright light of various wavelengths. The putative supernova remnant discovered by Spitzer did not have enough dust around it to amplify its final death throes.

In fact, when Morris and his team first found this object, the thought that it could be a supernova remnant did not immediately cross their minds. The object was completely invisible to previous all-sky surveys taken by radio and X-ray telescopes. It did not even show up in visible-light images. Team members thought that the object was most likely a planetary nebula, a star whose outer layers are gently puffed off in its last stages of life.

"There are various flavors of planetary nebulas; however, these objects normally have a bright star in the middle, a lot of dust, and a big range of chemistry. Our object shows none of this," said Morris.

For two years the team sifted through astronomical archives, literature, and additional Spitzer data in hopes of determining what the source could be. After months of comparing Spitzer's observations of the source to many examples from other object classes, Morris' team carefully ruled out the possibility that the source could be anything other than a supernova remnant.

The team was further inclined to believe this theory when they found traces of oxygen in the region with Spitzer's infrared spectrograph. Many known supernova remnants are surrounded by oxygen gas released from the cores of their aging stars.

Morris is currently planning to conduct deep radio observations of the object to confirm that it is indeed a supernova remnant. If his suspicions are correct, it will be the first supernova remnant ever to be discovered solely by its infrared properties. At 25 times the mass of our sun, the object will be among the three smallest and youngest supernova remnants in the Milky Way.

Source: NASA, JPL, by Whitney Clavin

Related stories:

Japanese physicists aim to unlock universe's mysteries
As the world's scientists try to unzip mysteries about the universe, Japan is set to open its largest atomic science park to study the world at its smallest level.
Most Black Holes Might Come in Only Small and Large
(PhysOrg.com) -- Black holes are sometimes huge cosmic beasts, billions of times the mass of our sun, and sometimes petite with just a few times the sun's mass. But do black holes also come in size medium? A new study suggests that, for the most part, the answer is no.
The Quiet Explosion: Object intermediate between normal supernovae and gamma-ray bursts found
A European-led team of astronomers are providing hints that a recent supernova may not be as normal as initially thought. Instead, the star that exploded is now understood to have collapsed into a black hole, producing a weak jet, typical of much more violent events, the so-called gamma-ray bursts. The object, SN 2008D, is thus probably among the weakest explosions that produce very fast moving jets. This discovery represents a crucial milestone in the understanding of the most violent phenomena observed in the Universe.
Not a Quirk But a Quark ... a Quark Star!
Astronomers recently announced that they have found a novel explanation for a rare type of super-luminous stellar explosion that may have produced a new type of object known as a quark star.
Detective astronomers unearth hidden celestial gem
ESA’s orbiting X-ray observatory XMM-Newton has re-discovered an ignored celestial gem. The object in question is one of the youngest and brightest supernova remnants in the Milky Way, the corpse of a star that exploded around 1000 years ago.
Hubble Space Telescope Spies Galaxy/Black Hole Evolution in Action
A set of 29 Hubble Space Telescope (HST) images of an exotic type of active galaxy known as a "post-starburst quasar" show that interactions and mergers drive both galaxy evolution and the growth of super-massive black holes at their centers.
Famous Supernovae Still Echo Across the Milky Way
While walking home on November 11, 1572, astronomer Tycho Brahe idly glanced at the sky. He was surprised to see a bright star in the constellation Cassiopeia that hadn’t been there before. The new star, which we now know to be the result of a stellar explosion or supernova, grew brighter than Venus and was visible in daylight for about two weeks. It then slowly faded until vanishing in March 1574, 16 months after its discovery.
Scientists find giant ring encircling exotic dead star
One of the most powerful eruptions in the universe might have spun an infrared ring around a rare and exotic star known as a magnetar, a highly magnetized neutron star and the remnant of a brilliant supernova explosion signaling the death throes of a massive star.

News discussion:

Space & Earth science news