PTF10fqs: A Luminous Red Nova in the Spiral Galaxy Messier 99

TL;DR

The paper reports the discovery of PTF10fqs, a luminous red transient in Messier 99, which fills the luminosity gap between novae and supernovae, and discusses its properties and potential significance.

Contribution

This is the first detailed observation and characterization of PTF10fqs, a transient that bridges the luminosity gap, providing new data on these mysterious explosions.

Findings

PTF10fqs has a peak luminosity of Mr = -12.3.

It shows a red color and slow evolution over 68 days.

Spectra reveal intermediate-width hydrogen and narrow calcium emission lines.

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 PTF10fqs, 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 H (930 km/s) and narrow calcium emission lines. The explosion signature (the light curve and spectra) is overall similar to thatof M85OT2006-1, SN2008S, and NGC300OT. The origin of these events is shrouded in mystery and controversy (and in some cases, in dust). PTF10fqs shows some evidence of a broad feature (around 8600A) that may suggest very large velocities (10,000 km/s) 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.