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Post Info TOPIC: Possible supernova in PGC 027776
Blobrana


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Posts: 131433
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SN 2010jl
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Title: Type IIn Supernova SN 2010jl: Optical Observations for Over 500 Days After Explosion
Authors: Tianmeng Zhang, Xiaofeng Wang, Chao Wu, Juncheng Chen, Jia Chen, Qin Liu, Fang Huang, Jide Liang, Xulin Zhao, Lin Li, Min Wang, Michel Dennefeld, Jujia Zhang, Meng Zhai, Hong Wu, Zhou Fan, Hu Zou, Xu Zhou, Jun Ma

We present extensive optical observations of a Type IIn supernova (SN) 2010jl for the first 1.5 years after the discovery. The UBVRI light curves demonstrated an interesting two-stage evolution during the nebular phase, which almost flatten out after about 90 days from the optical maximum. SN 2010jl has one of the highest intrinsic H_alpha luminosity ever recorded for a SN IIn, especially at late phase, suggesting a strong interaction of SN ejecta with the dense circumstellar material (CSM) ejected by the progenitor. This is also indicated by the remarkably strong Balmer lines persisting in the optical spectra. One interesting spectral evolution about SN 2010jl is the appearance of asymmetry of the Balmer lines. These lines can be well decomposed into a narrow component and an intermediate-width component. The intermediate-width component showed a steady increase in both strength and blueshift with time until t ~ 400 days after maximum, but it became less blueshifted at t ~ 500 days when the line profile appeared relatively symmetric again. Owing to that a pure reddening effect will lead to a sudden decline of the light curves and a progressive blueshift of the spectral lines, we therefore propose that the asymmetric profiles of H lines seen in SN 2010jl is unlikely due to the extinction by newly formed dust inside the ejecta, contrary to the explanation by some early studies. Based on a simple CSM-interaction model, we speculate that the progenitor of SN 2010jl may suffer a gigantic mass loss (~ 30-50 solar masses) in a few decades before explosion. Considering a slow moving stellar wind (e.g., ~ 28 km/s) inferred for the preexisting, dense CSM shell and the extremely high mass-loss rate (1-2 solar masses per yr), we suggest that the progenitor of SN 2010jl might have experienced a red supergiant stage and explode finally as a post-red supergiant star with an initial mass above 30-40 solar masses.

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Blobrana


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Posts: 131433
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Supernova 2010jl
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  A Supernova Cocoon Breakthrough

Observations with NASA's Chandra X-ray Observatory have provided the first X-ray evidence of a supernova shock wave breaking through a cocoon of gas surrounding the star that exploded. This discovery may help astronomers understand why some supernovas are much more powerful than others.
On November 3, 2010, a supernova was discovered in the galaxy UGC 5189A, located about 160 million light years away. Using data from the All Sky Automated Survey telescope in Hawaii taken earlier, astronomers determined this supernova exploded in early October 2010 (in Earth's time-frame).
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Blobrana


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Title: Strong Evolution of X-Ray Absorption in the Type IIn Supernova SN 2010jl
Authors: Poonam Chandra, Roger A. Chevalier, Christopher M. Irwin, Nikolai Chugai, Claes Fransson, Alicia M. Soderberg

We report two epochs of Chandra-ACIS X-ray imaging spectroscopy of the nearby bright Type IIn supernova SN 2010jl, taken around 2 months and then a year after the explosion. The majority of the X-ray emission in both the spectra is characterised by a high temperature (\ga 10 keV) and is likely to be from the forward shocked region resulting from circumstellar interaction. The absorption column density in the first spectrum is high, ~ 10^{24} cm^{-2}, more than 3 orders of magnitude higher than the Galactic absorption column, and we attribute it to absorption by circumstellar matter. In the second epoch observation, the column density has decreased by a factor of 3, as expected for shock propagation in the circumstellar medium. The unabsorbed 0.2-10 keV luminosity at both epochs is ~7 x 10^{41} erg/s. The 6.4 keV Fe line clearly present in the first spectrum is not detected in the second spectrum. The strength of the fluorescent line is roughly that expected for the column density of circumstellar gas, provided the Fe is not highly ionised. There is also evidence for an absorbed power law component in both the spectra, which we attribute to a background ultraluminous X-ray source.

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Blobrana


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Asymmetric supernova explosions
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As one knows from the Sun, stars are nearly perfect spheres of glowing gas. One might expect that a star retained this shape, even when dramatic events happen during its lifetime. Therefore, both the slow, steady stellar winds from massive stars, as well as the cataclysmic explosions called supernovae, in which some stars end their lives, were assumed to be symmetric -quasi-spherical clouds of matter expelled into space.
However, recent developments in the observation of supernovae are providing increasing evidence that the explosion of a (nearly round) star can result in a strongly deformed fireball.
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Blobrana


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Posts: 131433
Date:
Supernova 2010jl
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Title: Asymmetries in the Type IIn SN2010jl
Authors: F. Patat, S. Taubenberger, S. Benetti, A. Pastorello, A. Harutyunyan

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Title: Asymmetries in the type IIn SN 2010jl
Authors: F. Patat, S. Taubenberger, S. Benetti, A. Pastorello and A. Harutyunyan

Aims. We study possible signs of asymmetry in the luminous type IIn SN 2010jl, to obtain independent information about its explosion geometry.
Methods. We performed optical linear spectropolarimetry of SN 2010jl two weeks after the discovery, in the spectral range 3700-8800 A.
Results. The object exhibits a continuum polarisation at a very significant and almost constant level (1.7-2.0%). Distinctive line depolarisation is seen at the positions of the strongest emission features, such as H and H. This implies that the line forming region is well above the photosphere. The continuum polarisation level (1.7-2.0%) indicates a substantial asphericity, of axial ratio =< 0.7. The almost complete depolarisation seen at H is indicative of a very low level of interstellar polarisation (=<0.3%). This rules out the presence of relevant amounts of dust in the progenitor environment at the time of our observations. From a polarimetric point of view, SN 2010jl appears to be very similar to the two other well-studied type IIn SNe 1997eg and 1998S, establishing a strong link between members of this class of objects.

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Blobrana


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Confirmed:
The type IIn supernova, 2010jl,  was discovered by J. Newton and T. Puckett on the 2nd November, 2010, near the galaxy PGC 027776 in the constellation Leo.
The supernova is located 2.4" East and 7.7" North from the center of the galaxy.

Position (2000): RA  09 42 53.33, Dec    +09°29'41.8"

CBET 2532 (Subscription)

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Blobrana


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Posts: 131433
Date:
Possible supernova in PGC 027776
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A possible magnitude 12.9 supernova was discovered by T. Puckett and J. Newton  on the 2nd November, 2010, near the galaxy PGC 027776 (UGC 5189A) in the constellation Leo.
The supernova is located 2.4" East and 7.7" North from the center of the galaxy.
As yet they type is unknown.

Position (2000): RA  09 42 53.33, Dec    +09°29'41".8

CBET 2532 (Subscription)

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