SN 2008ax

SN 2008ax was a helium-rich type Ib core-collapse supernova in the interacting galaxy NGC 4490.[3] It was independently discovered on 3 March 2008 by LOSS[5] and 4 March by Koichi Itagaki.[6] The site had been monitored six hours before discovery, thus constraining the time of the explosion breakout.[3] It was the third-brightest supernova of 2008.[7] The brightness in the B-band peaked about 20 days after the explosion.[3] X-ray emissions were detected from the event, which are most likely the result of shock heating from the supernova ejecta and circumstellar material.[8]

SN 2008ax
Position of SN 2008ax in NGC 4490; image courtesy of Hunter Wilson
Event typeSupernova
Type Ib[1]
Date3 March 2008
ConstellationCanes Venatici
Right ascension12h 30m 40.80s[2]
Declination+41° 38 16.1[2]
EpochJ2000.0
Galactic coordinatesb = 137.95°, l = +74.88°[2]
Distance31 Mly (9.6 Mpc)[3]
SourceNGC 4490
Peak apparent magnitude+13.0[4]

Images of the source location made using the Hubble Space Telescope in 2011 and 2013 were used to identify the progenitor. If it was a single star, the images are compatible with a supergiant star with a class of B to mid-A type. However, this is not favored by models which indicate the progenitor had a relatively low mass of 4–5 M and extended hydrogen-rich atmosphere with a radius of 30–40 R. An alternative, more plausible model suggests the progenitor was part of an interacting binary system where much of the atmosphere was lost through mass transfer to the companion.[1]

References

  1. Folatelli, Gastón; et al. (October 2015). "The Progenitor of the Type IIb SN 2008ax Revisited". The Astrophysical Journal. 811 (2): 13. arXiv:1509.01588. Bibcode:2015ApJ...811..147F. doi:10.1088/0004-637X/811/2/147. S2CID 53463754. 147.
  2. Drake, A. J.; et al. (May 2009). "First Results from the Catalina Real-Time Transient Survey". The Astrophysical Journal. 696 (1): 870–884. arXiv:0809.1394. Bibcode:2009ApJ...696..870D. doi:10.1088/0004-637X/696/1/870. S2CID 7530040.
  3. Pastorello, A.; et al. (September 2008). "The Type IIb SN 2008ax: spectral and light curve evolution". Monthly Notices of the Royal Astronomical Society. 389 (2): 955–966. arXiv:0805.1914. Bibcode:2008MNRAS.389..955P. doi:10.1111/j.1365-2966.2008.13618.x. S2CID 16483475.
  4. David Bishop. "Supernova 2008ax in NGC 4490". supernovae.net (International Supernovae Network). Archived from the original on 8 April 2010. Retrieved 7 June 2010.
  5. Mostardi, R.; et al. (March 2008). Green, D. W. E. (ed.). "Possible Supernova in NGC 4490". Central Bureau Electronic Telegrams. 1280 (1): 1. Bibcode:2008CBET.1280....1M.
  6. Nakano, S. (March 2008). Green, D. W. E. (ed.). "Supernova 2008ax in NGC 4490". Central Bureau Electronic Telegrams. 1286 (1): 1. Bibcode:2008CBET.1286....1N.
  7. David Bishop. "Bright Supernovae - 2008". supernovae.net (International Supernovae Network). Archived from the original on 27 September 2011. Retrieved 7 June 2010.
  8. Roming, P. W. A.; et al. (October 2009). "Multi-Wavelength Properties of the Type IIb SN 2008ax". The Astrophysical Journal Letters. 704 (2): L118–L123. arXiv:0909.0967. Bibcode:2009ApJ...704L.118R. doi:10.1088/0004-637X/704/2/L118. S2CID 51315301.
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