August 21, 2014

28.03.11: Einstein@Home Bags Pulsar #2.

Pulsars in a tight orbit…(Artists conception credit: NASA/Goddard).

Crowd-sourced citizen science bagged another astrophysical biggie this month. Einstein@Home, everyone’s favorite desktop screensaver program, announced the discovery of a new potential pulsar pair earlier this month. Like SETI@Home, this program utilizes idle computing time to analyze avalanches of data looking for signals. In the case of Einstein@Home, the data received comes from LIGO,VIRGO, and more recently, Arecibo. [Read more...]

Astro-Challenge: Spy a Microquasar.

Artists' Conception of SS 433. (NASA/CXC/M. Weiss).

Artists' Conception of SS 433. (NASA/CXC/M. Weiss).

 

   So, you’ve seen everything the night sky has to offer? You say you’ve seen all breeds of eclipses and deep sky objects, and have grown tired of showing the neighbors Saturn and the Ring Nebula? Well, we’ve got a challenge for you. This week’s object will require dark skies, a good finder chart, and a generous aperture telescope.  About 4 degrees northwest of the 3rd magnitude star Delta Aquilae lies +14.1 magnitude SS 433. [Read more...]

02.04.10- Cassiopeia A: A Quark Star?

Cas A as imaged by Hubble. (Credit: NASA/ESA/ Robert Fesen/James Long).

Cas A as imaged by Hubble. (Credit: NASA/ESA/ Robert Fesen/James Long).

   

   The supernova remnant Cassiopeia A holds a compelling astrophysical mystery. Located about 10,000 light years away, this strong radio source was identified in 1947 and remains the most recent galactic supernova known. One slightly odd fact revolves around Cas A; despite its having burst about 325 years ago as seen from Earth, no reliable records exist of the event. Evidence of the event may have been obscured by intervening galactic dust.  Some intriguing indications show that John Flamsteed may have misidentified the supernova as a sixth magnitude star in Cassiopeia during one of his surveys, but now Cas A may be the home of a even more bizarre denizen; a quark star. This theory stems from the fact that the remnant host appears to be only 10 km across, smaller than your average neutron star. At that density, neutrons loose all individual identity and merge into a huge ball of quark strange matter, a “strange” object indeed. First spotted by the Chandra X-Ray observatory in 1999, this “quark star” would be the first of its kind. Of course, an alternative hypothesis, put forth by Wynn Ho and Craig Heinke of Southampton University, states that we’re merely seeing a normal neutron star of about 25 km in diameter shining through a carbon atom haze. Does astrophysics need to get any weirder?

23.10.09:Fermi Pegs Gamma-Ray Pulsars.

the gamma-ray sky as seen by Fermi. (Credit: NASA/DOE/International LAT team).

The gamma-ray sky as seen by Fermi. the plane of our galaxy runs down the center, while pulsars dot the periphery. (Credit: NASA/DOE/International LAT team).

NASA’s Large Area Telescope aboard the orbiting Fermi gamma-ray observatory continues to turn out some amazing science, picking up where Compton left off in 2002 as it surveys the gamma-ray sky. Of particular interest are gamma-rays emitted from pulsars. Pulsars are the swiftly rotating remnants of massive stars that have gone supernova, leaving a superdense core in their wake. These are sometimes called “neutron stars” because the matter comprising them is packed so tightly the individual nuclei are literally stacked end to end, making a spoonful weigh as much as a mountain! After all, most ordinary matter is made of….nothing. A neutron star can be thought of as a large, singular atomic nucleus, again weird stuff. Most of the 1,800 pulsars thus detected are because of their copious radio emissions beaming from their poles. Thus, we have to be in the line of sight before we see their blinking radio pulsations. Enter Fermi, which has thus far spotted 16 new pulsars via their gamma-ray emissions alone. This promises to aid in identifying pulsars whose poles aren’t tipped to our line of sight, which are probably in the majority. But even the gamma-ray sky is relatively dim; for example, the Vela pulsar is one of the brightest in the sky, and it emits a mere 1 gamma-ray photon every 2 minutes! Initially dubbed “Little Green Men” (LGMs!) during their discovery in the 1960′s, pulsars were soon naturally explained, but still continue to amaze. Watch this space and the Fermi mission for news from the high energy end of the spectrum!