Morford, JC; Fenech, DM; Prinja, RK; Blomme, R; Yates, JA; (2016) e-MERLIN 21 cm constraints on the mass-loss rates of OB stars in Cyg OB2. Monthly Notices Of The Royal Astronomical Society , 463 (1) pp. 763-770. 10.1093/mnras/stw1914.

Preview

Text Morford_e-MERLIN 21 cm constraints_VoR.pdf - Published Version Download (400kB) | Preview

Abstract

We present e-MERLIN 21 cm (L-band) observations of single luminous OB stars in the Cygnus OB2 association, from the Cyg OB2 Radio Survey Legacy programme. The radio observations potentially offer the most straightforward, least model-dependent, determinations of mass-loss rates, and can be used to help resolve current discrepancies in mass-loss rates via clumped and structured hot star winds. We report here that the 21 cm flux densities of O3 to O6 supergiant and giant stars are less than ∼70 μJy. These fluxes may be translated to ‘smooth’ wind mass-loss upper limits of ∼4.4–4.8 × 10−6 M⊙ yr −1 for O3 supergiants and ≲2.9 × 10−6 M⊙ yr −1 for B0 to B1 supergiants. The first ever resolved 21 cm detections of the hypergiant (and luminous blue variable candidate) Cyg OB2 #12 are discussed; for multiple observations separated by 14 d, we detect an ∼69 per cent increase in its flux density. Our constraints on the upper limits for the mass-loss rates of evolved OB stars in Cyg OB2 support the model that the inner wind region close to the stellar surface (where Hα forms) is more clumped than the very extended geometric region sampled by our radio observations.

Download activity - last month

Export as CSVJSONXML

Download activity - last 12 months

Export as XMLCSVJSON

Downloads by country - last 12 months

Export as XMLCSVJSON

Archive Staff Only

View Item