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Date and Time of the Query: 2019-05-19 T19:30:25 PDT
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Notes for object SN 1997bs

1 note(s) found in NED.


1. 1999AJ....118.2331V
Re:SN 1997bs
A pair of archival F606W images of NGC 3627, which is also host to
SN 1989B (see section 3.3.13), was obtained. These images were taken
well before the SN IIn 1997bs was discovered (Treffers et al. 1997).
Although SN 1997bs has an absolute position (Cavagna 1997), we used
ground-based images, HST images from later Cycles, and the discovery
images to locate the SN environment, which we show in Figure 7a. We are
able to assign a 1" radius uncertainty in the position. Within the error
circle is a star with m_F606W_ = 22.86 +/- 0.16 mag on 1994 December 28.
For distance modulus m - M = 30.28 (Saha et al. 1997), this corresponds
to M_V_ ~ -7.4 mag for the star. In Figures 7b and 7c we show the same
field in subsequent WFPC2 F555W images made as part of program GO 6549.
On 1997 November 12 (Figure 7b), nearly 7 months after the SN's
discovery, the star's position is coincident with that of the SN, which
had m_F555W_ = 21.42 +/- 0.03 mag. On 1998 January 10 (Figure 7c) the
star had faded to m_F555W_ = 23.37 +/- 0.05 mag, below its original
brightness. Thus, we conclude that this star was the progenitor of
SN 1997bs. Although we have no color information for this star, its
absolute magnitude is consistent with it having been an extremely
luminous supergiant star. This is only likely the fourth SN progenitor
to be identified in pre-explosion images (see section 1).
Goodrich et al. (1989) and Filippenko et al. (1995b) analyze the
case of SN 1961V, concluding that it was a superoutburst of a luminous
blue variable star, resembling the enormous eruptions sometimes
experienced by {eta} Car. Supernovae with relatively similar spectra and
low luminosities include SN 1999bw and SN 1997bs; they might be
additional examples of such outbursts (Filippenko, Li, & Modjaz 1999).
Unlike normal SNe II, in which the progenitor destroys itself and
creates a compact remnant (neutron star or black hole), here the
progenitor survives the explosion reasonably unharmed. Thus, in a sense
these are not "genuine" SNe. The detection of a very luminous progenitor
to SN 1997bs provides some evidence for this hypothesis, but the real
test will be whether the star is still visible in future HST images
obtained years after the outburst.


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