* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> Events -> Supernova 2008bk
Post Info TOPIC: Supernova 2008bk
Blobrana


L

Posts: 131433
Date:
RE: Supernova 2008bk
Permalink  
 

Title: A study of the low-luminosity Type II-Plateau supernova 2008bk
Author: Sergey Lisakov, Luc Dessart, D. John Hillier, Roni Waldman, Eli Livne

Supernova (SN) 2008bk is a well observed low-luminosity Type II event visually associated with a low-mass red-supergiant progenitor. To model SN 2008bk, we evolve a 12Msun star from the main sequence until core collapse, when it has a total mass of 9.88Msun, a He-core mass of 3.22Msun, and a radius of 502Rsun. We then artificially trigger an explosion that produces 8.29Msun of ejecta with a total energy of 2.5x10^50erg and ~0.009Msun of 56Ni. We model the subsequent evolution of the ejecta with non-Local-Thermodynamic-Equilibrium time-dependent radiative transfer. Although somewhat too luminous and energetic, this model reproduces satisfactorily the multi-band light curves and multi-epoch spectra of SN 2008bk, confirming the suitability of a low-mass massive star progenitor. As in other low-luminosity SNe II, the structured Halpha profile at the end of the plateau phase is probably caused by BaII 6496.9A rather than asphericity. We discuss the sensitivity of our results to changes in progenitor radius and mass, as well as chemical mixing. A 15% increase in progenitor radius causes a 15% increase in luminosity and a 0.2mag V-band brightening of the plateau but leaves its length unaffected. An increase in ejecta mass by 10% lengthens the plateau by ~10d. Chemical mixing introduces slight changes to the bolometric light curve, limited to the end of the plateau, but has a large impact on colours and spectra at nebular times.

Read more (2608kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: An Echo of Supernova 2008bk
Authors: Schuyler D. Van Dyk (Spitzer Science Center/IPAC/Caltech)

I have discovered a prominent light echo around the low-luminosity Type II-Plateau Supernova (SN) 2008bk in NGC 7793, seen in archival images obtained with the Wide Field Channel of the Advanced Camera for Surveys on-board the Hubble Space Telescope (HST). The echo is a partial ring, brighter to the north and east than to the south and west. The analysis of the echo I present suggests that it is due to the SN light pulse scattered by a sheet, or sheets, of dust located ~15 pc from the SN. The composition of the dust is assumed to be of standard Galactic diffuse interstellar grains. The visual extinction of the dust responsible for the echo is A_V ~ 0.05 mag, in addition to the extinction due to the Galactic foreground toward the host galaxy. That the SN experienced much less overall extinction implies that it is seen through a less dense portion of the interstellar medium in its environment. The late-time HST photometry of SN 2008bk also clearly demonstrates that the progenitor star has vanished.

Read more (187kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

A magnitude 12.6 supernova, 2008bk, was discovered  on the 25th March, 2008, by Berto Monard in the spiral galaxy  NGC 7793 in the constellation Sculptor.
The supernova is located 26" east and 138" north of the nucleus of  the galaxy.

Position(2000):  R.A. = 23h57m47s.5, Dec. = -32°33'24"

As yet the Type is unknown.

Supernova 2008bk.kmz

CBET 1315  (Subscription)

__________________
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> Events -> Supernova 2008bk


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard