A Challenging Object: Supernova Impostor SN 2009ip Is Back

American Association of Variable Star Observers (AAVSO)
Sun, 09/23/2012 - 21:05

I want to draw attention to a supernova impostor that has flared back up, and some are saying it could have gone supernova.  Here is a link to the relevant Astronomer's Telegram:


Supernova imposters are visually as bright as supernova but they do not destroy the progenitor and some of them, like SN 2009ip have a repeat eruption.  As the ATEL reports, Nathan Smith has guessed that this one might have popped off as a true supernova this time.  Eta Carinae's great eruption in the 1840's is the prototype for this kind of object in our own galaxy.

Observing this object is a stretch for most northern hemisphere observers because it is at Declination -29.  However it is an object of great interest and any good CCD photometry would be appreciated.  Johnson V is normally most helpful.  Cousins R and I are also useful for supernova impostors (because dust production can make them redder as they evolve).

Here is a link to photo on flicker with the object marked.


Note that the star to the immeadiate northeast of the target is pretty red.  So depending on the airmass you are looking through and the filter you are using those two stars may be blended or appear as individual stars.  It is my belief, based on data from Deep Sky Survey images that the nearby star to the northeast is faint enough in V and R that SN 2009ip overwhelms it completely in the photometric recudtions.   The images that I took on September 11, 2012 show 2 distinct stars in the I-band but only a single star in the V and R bands.  In my V and R band images the sky level was higher than the quoted brightness of the star to the immeadiate north-east.  

I have made a VPHOT sequence for this that I am willing to share with anyone who wants to take some frames and reduce them in VPHOT.  You can reach me here or jmart5_at_uis.edu

American Association of Variable Star Observers (AAVSO)
Powering the Second 2012 Outburst of SN 2009ip by Repeating Bina

There is a new paper out on this interesting object- the authors propose a merger between an LBV and a smaller compact companion- wild!

Powering the Second 2012 Outburst of SN 2009ip by Repeating Binary Interaction

Abstract: We propose that the major 2012 outburst of the supernova impostor SN 2009ip was powered by an extended and repeated interaction between the Luminous Blue Variable (LBV) and a more compact companion. Motivated by the recent analysis of Margutti et al. (2013) of ejected clumps and shells we consider two scenarios. In both scenarios the major 2012b outburst of ~5 * 10^{49} erg was powered by accretion of ~ 2-5 solar masses onto the companion during a periastron passage (the first passage) of the binary system approximately 20 days before the observed maximum of the light curve. In the first, the surviving companion scenario, the companion was not destructed and still exists in the system after the outburst. It ejected partial shells (or collimated outflows or clumps) for two consecutive periastron passages after the major one. The orbital period was reduced from ~38 days to ~25 days as a result of the mass transfer process that took place during the first periastron passage. In the second, the merger scenario, some partial shells/clumps were ejected also in a second periastron passage that took place ~20 days after the first one. After this second periastron passage the companion dived too deep into the LBV envelope to launch more outflows, and merged with the LBV.


American Association of Variable Star Observers (AAVSO)
It's Got A Sense of Humor For Sure

Well.... I hesitate to say anything because this object seems to sense when anyone makes a prediction and then goes in the opposite direction.  But I'll own up to that it didn't make it back to 14th magnitude.  It turned over during the week and dimmed to about 15th.