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Optical study of type II event SN 2008gz

This study presents optical observations of the Type II supernova event SN 2008gz, including photometric and spectroscopic data. The event is analyzed and compared with other Type II events, showing similarities in characteristics. The host galaxy, NGC 3672, is also discussed.

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Optical study of type II event SN 2008gz

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  1. Optical study of type II event SN 2008gz Rupak Roy Aryabhatta Research Institute of Observational Sciences (ARIES)‏ Nainital, India Many Faces of GRB Phenomena- Optics vs High Energy October 12 – 16, 2009 SAO, RAS, Russia

  2. Locations of Indian Optical Facilities Starting from IAO, Hanle (Latitude : 32d 46m 46s N, Longitude : 78d 57m 51s E)‏ Up-to VBO, Kavalor (Latitude : 12d 34m N, Longitude : 78d 50m E)‏

  3. Observations of Transient Events From ARIES • More than 50 GRB fields since 1999 • More than 30 optical afterglows • Earliest optical Observations GRB 000301C GRB 020405 GRB 060124 Recently observed GRB afterglows GRB 090424 GRB 080430 GRB 071010A GRB 071003 ARIES (~ 29d N, 79d E)‏ More than 15 SNe have been monitored.

  4. Chevalier

  5. Discovered on 5th November 2008, in the spiral galaxy NGC 3672. SN 2008gz We have carried out optical broadband (BVRI) photometric and low resolution spectroscopic observations of this event since 10th November 2008. Host Galaxy Information (From NASA/IPAC Extragalactic Database) : Nomenclature : NGC 3672 Coordinate (J2000) :  = 11h 25m 02.5s  = -09d 47m 43s Radial Velocity : 1862  4 km/s Redshift : 0.006211  0.000013 Luminosity Distance : 30.8 Mpc

  6. Observations from India Photometric Observations were mainly carried out from 1.04-m ST, Nainital Spectroscopic Observations were performedfrom 2.00-m IGO, Pune, SN 2008gz

  7. Over The Globe 0.61-m, Perth-Lowell 2.00-m, IGO, Girawali 1.04-m, ST, ARIES 3.58-m TNG, La Palma 3.58-m NTT, La Silla 6-m BTA, SAO

  8. SN 2007bm SN 2008gz Template Subtraction : Measurement of true flux After Template Subtraction

  9. Optical Light Curve According to Benetti et al, 2008 (CBET 1568 ), SN 2008gz was discovered nearly 62 days after Burst. We compare the BVRI light curves of SN 2008gz with type IIP SN 2004et under the constrain imposed through spectroscopy and found it as a type IIP SN, which just completed its Plateau phase

  10. Bolometric Light Curve & Ni mass estimation BVRI Bolometric Light Curve is derived for this SN over the span of observation and compared with that of two well studied type II events SN2004et & SN1987A. BVRI Bolometric Luminosity for SN 2008gz is ~ 3.1 x 1048 ergs : similar to SN 2004et & SN 1987A Estimated Ni mass ejected over the time span (following Hamuy, 2003) is around 0.05 M_sun. This is well inside the range specified by Hamuy, 2003. (between 0.0016 and 0.26 M_sun).

  11. Contributions from different bands

  12. Spectroscopic Observations of SN 2008gz +62 day +90 day +115 day +146 day +207 day +250 day

  13. SYNOW modelling of spectrum 11.11.2008 From 1st Spectrum, Benetti, et al. (CBET 1568) determined the velocity of expanding photosphere near about 6600 km/sec. This velocity is comparable with that of well studied type IIp (like SN 2004et) at the end of its plateau. They determined this velocity through the tool GELATO. The SYNOW modelling of 2nd and 3rd spectra shows that the velocity of photosphere around 100 days after the burst is ~ 4000 km/sec, which is the typical velocity of photosphere at very beginning of nebular phase. Minimum velocity of the shell where lines are formed is ~ 3,500 km/sec. 08.12.2008 The best fit of the model correspond to effective black body temperature of the photosphere ~ 4000 K.

  14. Late time Spectra 02.02.2009 03.04.2009 17.05.2009

  15. Velocity Profile

  16. Host Galaxy Spectrum Spectrum-090201 IGO, Pune, India

  17. Comparison with Other Galaxy Spectrum

  18. Nature of Host Galaxy NGC 3672 is plausibly a spiral galaxy of type Sb. NGC 3672 is at a redshift ~ 0.006172 which corresponds to the luminosity distance ~ 26.2 Mpc

  19. Preliminary Results The event was discovered nearly two months after the explosion Comparison of photometric and spectroscopic characteristic of this event with other type II events suggests that this event is of type IIP. The event was as energetic as type IIP event SN 2004et and SN 1987A. The region of the envelope producing H_alpha emission moves much faster than the regions which contain heavy elements and attached with the photosphere. So, probably the outer shell producing H_alpha is detached from the shells containing higher elements like iron and other.

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