The Continued Optical to Mid-Infrared Evolution of V838 Monocerotis
Abstract
The eruptive variable V838 Monocerotis (V838 Mon) gained notoriety in 2002 when it brightened nine magnitudes in a series of three outbursts and then rapidly evolved into an extremely cool supergiant. We present optical, near-infrared (near-IR), and mid-IR spectroscopic and photometric observations of V838 Mon obtained between 2008 and 2012 at the Apache Point Observatory 3.5 m, NASA IRTF 3 m, and Gemini South 8 m telescopes. We contemporaneously analyze the optical and IR spectroscopic properties of V838 Mon to arrive at a revised spectral type L3 supergiant and effective temperature {{T}eff}∼ 2000-2200 K. Because there are no existing optical observational data for L supergiants, we speculate that V838 Mon may represent the prototype for L supergiants in this wavelength regime. We find a low level of Hα emission present in the system, consistent with interaction between V838 Mon and its B3V binary; however, we cannot rule out a stellar collision as the genesis event, which could result in the observed Hα activity. Based upon a two-component blackbody fit to all wavelengths of our data, we conclude that, as of 2009, a shell of ejecta surrounded V838 Mon at a radius of R=263+/- 10 AU with a temperature of T=285+/- 2 K. This result is consistent with IR interferometric observations from the same era and predictions from the Lynch et al. model of the expanding system, which provides a simple framework for understanding this complicated system.
This publication is partially based on observations obtained with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium.- Publication:
-
The Astronomical Journal
- Pub Date:
- January 2015
- DOI:
- 10.1088/0004-6256/149/1/17
- arXiv:
- arXiv:1409.2513
- Bibcode:
- 2015AJ....149...17L
- Keywords:
-
- circumstellar matter;
- stars: general;
- stars: individual: V838 Monocerotis;
- stars: peculiar;
- stars: variables: general;
- stars: winds;
- outflows;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 6 pages, 2 tables, 6 figures