NOAO >   Observing Info >   Approved Programs >   2016A-0345

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Program Information for 2016A-0345


PI: Bruce McCollum, Catholic U. of America, mccollub@cua.edu
Address: 620 Michigan Ave, NE, Dept of Physics, Washington, DC, 20064 USA

CoI: Stuart Ryder, Australian Astronomical Observatory
CoI: Frederick Bruhweiler, Catholic U. of America
CoI: Lee Rottler, California Institute of Technology
CoI: Seppo Laine, IPAC

Title: Identifying the Progenitor Star for a New Red Transient

Abstract: Red transients (RTs) denote a recently discovered new class of stellar outburst. The unusual location of RTs in the brightness-time decay diagram falls in a distinct region from classical novae and SNe. The cause of these outbursts remain controversial. One such object, V1309 Sco, has been identified as a product of a stellar merger. The recent discovery of an RT in the nearby sprial galaxy, M83, from Spitzer IRAC imagery, is fortuitous because the field was imaged in 15 HST WFC3 bandpasses from the visual through the near-IR six years prior to the outburst. The SED derived from these data allows us a rare opportunity to identify the characteristics of the progenitor. The unknown nature of the progenitors has been a major proble in trying to model RTs. There are no spectra of progenitors, and the only one other RT progenitor has been classified using an extensive optical-IR SED. The fact that M83 has a well-determined distance (4.5 +/- 0.3 Mpc) based upon Cepheids will provide strong luminosity constraints for this object, which is another important input to models, and will make the spectral classsification for the progenitor robust. There are several candidate progenitor stars within a region~1 arscec in diameter in the WFC3 imagery. Because Spitzer IRAC resolution is 1.2"/pixel, the IRAC discovery image cannot be used to identify the progenitor star in WFC3 images. The absolute pointing uncertianties in the IRAC and WFC3 further combine to create a larger error encompassing several stellar candidates. Thus, we need to use Gemini/GSAOI JHK imagery, with comparable depth and resolution to the WFC3, to ascertain by inspection, which object underwent the outburst. The complete suite of 15 broad- and narrow-band HST images of the region in M83 will be used to determine the SED of the stellar precursor. We will also obtain two FLAMINGOS-2 spectra with the JH and HK dispersers of this object to compare with the few other RTs for which near-IR spectra in their first years of outburst exist. These data and the fact that the distance to M83 is well-determined will pose strong constraints for possible models explaining the process producing red transients.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2016A):  GEM-SQ/Flamingos2 -- 3.4hrs band 1 (GS-2016A-Q-17)


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