PTF 10fqs: A Luminous Red Nova in the Spiral Galaxy Messier 99
Filippenko, Alexei V.; Cenko, S. Bradley; Law, Nicholas M.; Li, Weidong; Tendulkar, Shriharsh P.; Dekany, Richard; Kasliwal, Mansi M.; Miller, Adam; Neill, James D.; Gal-Yam, Avishay; Helou, George; Smith, Roger; Ofek, Eran O.; Forster, Karl; Bildsten, Lars; Walters, Richard; Yaron, Ofer; Rahmer, Gustavo; Hale, David; Quimby, Robert M.; Zolkower, Jeff; Velur, Viswa; Henning, John; McKenna, Dan; Bloom, Joshua S.; Gehrels, Neil; Arcavi, Iair; Poznanski, Dovi; Fox, Derek B.; Nugent, Peter; Sullivan, Mark; Martin, D. Christopher; Jacobsen, Janet; Kennea, Jamie; Frail, Dale A.; Kulkarni, Shri R.; Green, Yoav; Howell, Jacob L.; Kleiser, Io; Starr, Dan; Bui, Kahnh; Blake, Cullen
United States, Israel, Canada, United Kingdom
Abstract
The Palomar Transient Factory (PTF) is systematically charting the optical transient and variable sky. A primary science driver of PTF is building a complete inventory of transients in the local universe (distance less than 200 Mpc). Here, we report the discovery of PTF 10fqs, a transient in the luminosity "gap" between novae and supernovae. Located on a spiral arm of Messier 99, PTF 10fqs has a peak luminosity of Mr = -12.3, red color (g - r = 1.0), and is slowly evolving (decayed by 1 mag in 68 days). It has a spectrum dominated by intermediate-width Hα (≈930 km s-1) and narrow calcium emission lines. The explosion signature (the light curve and spectra) is overall similar to that of M85 OT2006-1, SN 2008S, and NGC 300 OT. The origin of these events is shrouded in mystery and controversy (and in some cases, in dust). PTF 10fqs shows some evidence of a broad feature (around 8600 Å) that may suggest very large velocities (≈10,000 km s-1) in this explosion. Ongoing surveys can be expected to find a few such events per year. Sensitive spectroscopy, infrared monitoring, and statistics (e.g., disk versus bulge) will eventually make it possible for astronomers to unravel the nature of these mysterious explosions.