* Astronomy

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RE: Cassiopeia A

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NASA'S Chandra Finds Superfluid in Neutron Star's Core

This new research has allowed the teams to place the first observational constraints on a range of properties of superfluid material in neutron stars. The critical temperature was constrained to between one half a billion to just under a billion degrees Celsius. A wide region of the neutron star is expected to be forming a neutron superfluid as observed now, and to fully explain the rapid cooling, the protons in the neutron star must have formed a superfluid even earlier after the explosion. Because they are charged particles, the protons also form a superconductor.
Using a model that has been constrained by the Chandra observations, the future behaviour of the neutron star has been predicted. The rapid cooling is expected to continue for a few decades and then it should slow down.
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Superfluid and superconductor discovered in a star's core

The discovery of the rapid decline in the temperature of an ultradense star has provided the first evidence for a bizarre state of matter in the core of a star. Two independent research teams have used data from NASA's Chandra X-ray Observatory to show that the interior of a neutron star contains superfluid and superconducting matter, a conclusion with important implications for understanding nuclear interactions in matter at the highest known densities. The teams publish their research separately in the journals Monthly Notices of the Royal Astronomical Society Letters and Physical Review Letters.
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Title: Rapid Cooling of the Neutron Star in Cassiopeia A Triggered by Neutron Superfluidity in Dense Matter
Authors: Dany Page (1), Madappa Prakash (2), James M. Lattimer (3), Andrew W. Steiner (4) ((1) Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, (2) Department of Physics and Astrononmy, Ohio University (3) Department of Physics and Astronomy, State University of New York at Stony Brook (4) Joint Institute for Nuclear Astrophysics, National Superconducting Cyclotron Laboratory and Department of Physics and Astrononmy, Michigan State University)
(Version v2)

We propose that the observed cooling of the neutron star in Cassiopeia A is due to enhanced neutrino emission from the recent onset of the breaking and formation of neutron Cooper pairs in the 3P2 channel. We find that the critical temperature for this superfluid transition is ~0.5x10^9 K. The observed rapidity of the cooling implies that protons were already in a superconducting state with a larger critical temperature. Our prediction that this cooling will continue for several decades at the present rate can be tested by continuous monitoring of this neutron star.

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Superfluid state for Galaxy's youngest neutron star?

Two teams of astrophysicists might have found the first direct evidence that the interiors of neutron stars - the husk left behind after a massive star explodes - exist in a strange, frictionless state known as a superfluid. The teams found that the temperature of a young neutron star in our Galaxy is dropping faster than can be explained by standard cooling theories, matching researchers' expectations for a neutron star on its way to superfluidity.

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Title: The Three-Dimensional Structure of Interior Ejecta in Cassiopeia A at High Spectral Resolution
Authors: Karl Isensee, Lawrence Rudnick, Tracey DeLaney, J.D. Smith, Jeonghee Rho, William T. Reach, Takashi Kozasa, Haley Gomez

We used the Spitzer Space Telescope's Infrared Spectrograph to create a high resolution spectral map of the central region of the Cassiopeia A supernova remnant, allowing us to make a Doppler reconstruction of its 3D structure. The ejecta responsible for this emission have not yet encountered the remnant's reverse shock or the circumstellar medium, making it an ideal laboratory for exploring the dynamics of the supernova explosion itself. We observe that the O, Si, and S ejecta can form both sheet-like structures as well as filaments. Si and O, which come from different nucleosynthetic layers of the star, are observed to be coincident in velocity space in some regions, and separated by 500 km/s or more in others. Ejecta travelling toward us are, on average, ~900 km/s slower than the material travelling away from us. We compare our observations to recent supernova explosion models and find that no single model can simultaneously reproduce all the observed features. However, models of different supernova explosions can collectively produce the observed geometries and structures of the interior emission. We use the results from the models to address the conditions during the supernova explosion, concentrating on asymmetries in the shock structure. We also predict that the back surface of Cassiopeia A will begin brightening in ~30 years, and the front surface in ~100 years.

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Young and getting cooler - the early life of a neutron star

Observations of how the youngest-known neutron star has cooled over the past decade are giving astronomers new insights into the interior of these super-dense dead stars. Dr Wynn Ho will present the findings on Thursday April 15th at the RAS National Astronomy Meeting in Glasgow.
Dr Ho, of the University of Southampton, and Dr Craig Heinke, of the University of Alberta in Canada, measured the temperature of the neutron star in the Cassiopeia A supernova remnant using data obtained by NASAs Chandra X-ray Observatory between 2000 and 2009.

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Echoes of a Supernova

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Astronomers See Historical Supernova From New Angle

By observing visible "light echoes," astronomers have assembled one of the first 3-D perspectives of a cosmic object. The new view of the supernova remnant Cassiopeia A confirms that it formed during a lopsided explosion.
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Astronomers See Historical Supernova From a New Angle

Since Galileo first pointed a telescope at the sky 400 years ago, a myriad of technological advances have allowed astronomers to look at very faint objects, very distant objects, and even light that's invisible to the human eye. Yet, one aspect usually remains out of reach - the benefit of a 3-D perspective.
Our telescopes show the Milky Way galaxy only as it appears from one vantage point: our solar system. Now, using a simple but powerful technique, a group of astronomers led by Armin Rest of Harvard University has seen an exploding star or supernova from several angles.
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