A Search for Mass Loss on the Cepheid Instability Strip using H I 21 cm Line Observations
Abstract
We present the results of a search for H I 21 cm line emission from the circumstellar environments of four Galactic Cepheids (RS Pup, X Cyg, ζ Gem, and T Mon) based on observations with the Karl G. Jansky Very Large Array. The observations were aimed at detecting gas associated with previous or ongoing mass loss. Near the long-period Cepheid T Mon, we report the detection of a partial shell-like structure whose properties appear consistent with originating from an earlier epoch of Cepheid mass loss. At the distance of T Mon, the nebula would have a mass (H I+He) of ∼ 0.5{M}⊙ , or ∼6% of the stellar mass. Assuming that one-third of the nebular mass comprises swept-up interstellar gas, we estimate an implied mass-loss rate of \dot{M}∼ (0.6{--}2)× {10}-5 {M}⊙ yr-1. No clear signatures of circumstellar emission were found toward ζ Gem, RS Pup, or X Cyg, although in each case, line-of-sight confusion compromised portions of the spectral band. For the undetected stars, we derive model-dependent 3σ upper limits on the mass-loss rates, averaged over their lifetimes on the instability strip, of ≲ (0.3{--}6)× {10}-6 {M}⊙ yr-1 and estimate the total amount of mass lost to be less than a few percent of the stellar mass.
- Publication:
-
The Astronomical Journal
- Pub Date:
- December 2016
- DOI:
- 10.3847/0004-6256/152/6/200
- arXiv:
- arXiv:1609.06611
- Bibcode:
- 2016AJ....152..200M
- Keywords:
-
- circumstellar matter;
- radio lines: stars;
- stars: mass-loss;
- stars: variables: Cepheids;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted to AJ