* Astronomy

Blobrana · L

RE: Supernova 2008am

Blobrana · L

Texas Astronomers Find Super-luminous Supernova, Follow up with Fleet of Telescopes in Space, on Earth

Astronomers led by graduate student Emmanouil "Manos" Chatzopoulos and Dr. J. Craig Wheeler of The University of Texas at Austin have found another extremely bright, rare supernova to add to the new class of exploding stars that University of Texas astronomers identified a few years ago. Supernova 2008am is one of the most intrinsically bright exploding stars ever observed.
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Supernova 2008am is brightest supernova yet discovered

Texas astronomers have discovered one of the most intrinsically bright exploding stars ever observed - Supernova 2008am.
The research by graduate student Emmanouil 'Manos' Chatzopoulos and J. Craig Wheeler of The University of Texas at Austin has revealed that this supernova is the brightest 'self-interacting' supernova yet discovered.
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Title: SN2008am: A Super-Luminous Type IIn Supernova
Authors: E. Chatzopoulos, J. Craig Wheeler, J. Vinko, R. Quimby, E. L. Robinson, A. A. Miller, R. J. Foley, D. A. Perley, F. Yuan, C. Akerlof, J. S. Bloom

We present observations and interpretation of the Type IIn supernova SN 2008am discovered by the ROTSE Supernova Verification Project (RSVP). SN 2008am peaked at approximately -22.3 mag at a redshift of z=0.2338, giving it a peak luminosity of 3 x 10^{44}erg/s and making it one of the most luminous supernovae ever observed. The total radiated energy is ~ 2 x 10^{51} erg. Photometric observations in the ultraviolet, optical and infrared bands (J,H,Ks) constrain the SED evolution. We obtained six optical spectra of the supernova, five on the early decline from maximum light and a sixth nearly a year later plus a very late-time spectrum (~2 yr) of the host galaxy. The spectra of SN 2008am show strong Balmer-line and He I lambda 5876A emission with intermediate widths (~25A) in the first ~40 days after optical maximum. We examine a variety of models for the line wings and conclude that multiple scattering is most likely, implying that our spectra contain no specific information on the bulk flow velocity. We examine a variety of models for the ROTSE light curve subject to the rise time and the nature of the spectra, including radioactive decay, shocks in optically-thick and optically-thin circumstellar media (CSM) and a magnetar. The most successful model is one for which the CSM is optically-thick and in which diffusion of forward shock-deposited luminosity gives rise to the observed light curve. Diffusion of the shock-deposited energy from the forward shock is found to be important to account for the rising part of the light curve. Although there are differences in detail, SN 2008am appears to be closely related to other super-luminous Type IIn supernovae, SN 2006gy, SN 2006tf and perhaps SN 2008iy, that may represent the deaths of very massive LBV-type progenitors and for which the luminosity is powered by the interaction of the ejecta with a dense circumstellar medium.

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