Friday, July 29, 2011

Pluto's family grows, 07.29.11

The Hubble Telescope has added another great discovery to its repertoire; a fourth moon for Pluto. Temporarily assigned the name P4, it was discovered just this month orbiting around the dwarf planet with Charon, Nix, and Hydra, Pluto’s other moons.
Estimated to only be 8-21 miles wide, the tiny little rock is the smallest one to have been found orbiting Pluto. All the other moons orbiting Pluto are at least twice as large. Charon, the largest, is 648 miles across.
Astronomers anxiously wait for the day when the New Horizons spacecraft reaches the Pluto system in 2015. Launched in 2006, New Horizons is outfitted with a visible and infrared imager/spectrometer, an ultraviolet imaging spectrometer, a radio science experiment to measure atmospheric temperature and composition, a telescopic camera, a solar wind and plasma spectrometer, an energetic particle spectrometer, and a dust counter to measure how much dust New Horizons on its way to Pluto.
Credit: NASA. Image credit: NASA, ESA, and M. Showalter.

Pin the tail on the pulsar, 07.18.11

The Chandra X-Ray Observatory has seen something very interesting in recent months. In a paper published in the Astrophysical Journal, several astronomers note how they have witnessed a tail of sorts that appears to be spreading out from a pulsar. The pulsar is a rapidly spinning neutron star, lovingly dubbed PSR J0357+3205.
The blue in this composite image is the Chandra x-ray data, and the yellow is a digitized sky survey. The pulsar is actually at the upper right-hand edge of the “tail,” which is part of the reason why astronomers are left scratching their heads over the situation. If the tail were really originating from the pulsar, the brightest portion should most likely be nearest the star, yet in this case the brightest portion is at the opposite end. This is even more shocking when you do a little math and realize that the tail is somewhere in the neighborhood of 4.2 light years long. This would be a record-setting tail for a rotation-powered pulsar.
There are more reasons than one why this tail should not be originating from the star. We have to keep in mind, too, that astronomers are not 100% certain that this really is PSR J0357’s tail. More observations will need to be made to know for certain if this really is the pulsar’s tail and why it is providing such odd data readings.
Image and story credit: NASA.

Thursday, July 7, 2011

Gamma ray flares in binary star are a mystery, 07.07.11

Image credit: NASA.
Something very odd has happened 8,000 light years away in the southern constellation Crux. A binary star system has emitted strange gamma ray flares as the small pulsar star of the pair approached and passed through its closest point in orbit around the large Be-class star.
The Be-class star, designated LS 2883, is surrounded by a disc of gas. As the small neutron star, the pulsar B1259-63, approaches, it emits some gamma rays as it grazes through either side of the disc every 3.4 years.
On January 20 and February 21 of this year, however, when the pulsar approached the larger star, a strange series of powerful gamma ray flares occurred, which was highly out of character. A thorough barrage of scans and studies revealed no anomalies in the stars; no foreign objects, no strange chemical reactions, nothing that would elicit flares like those.
Since the two stars pass by each other that closely only every 3.4 years, it is going to be a while before scientists get another chance to study it again. it is believed that as the pulsar passes thru the disk of gas and dust, that the pulsars powerful magnetic field is accelerating captured electrons to very high energies causing these weird month-long gamma ray displays. It is truly a case where astronomers are finding more and more strange objects or events that can cause a gamma ray burst.

 Credit: NASA.