TY - JOUR
T1 - The circumstellar environments of NML Cygni and the cool hypergiants
AU - Schuster, Michael T.
AU - Humphreys, Roberta M.
AU - Marengo, Massimo
N1 - Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2006/1
Y1 - 2006/1
N2 - We present high-resolution HST WFPC2 images of compact nebulosity surrounding the cool M-type hypergiants NML Cyg, VX Sgr, and S Per. The powerful OH/IR source NML Cyg exhibits a peculiar bean-shaped asymmetric nebula that is coincident with the distribution of its H 2O vapor masers. We show that NML Cyg's circumstellar envelope is likely shaped by photodissociation from the powerful, nearby association Cyg OB2 inside the Cygnus X superbubble. The OH/IR sources VX Sgr and S Per have marginally resolved envelopes. S Per's circumstellar nebula appears elongated in a northeast/southwest orientation similar to that for its OH and H 2O masers, while VX Sgr is embedded in a spheroidal envelope. We find no evidence for circumstellar nebulosity around the intermediate-type hypergiants ρ Cas, HR 8752, and HR 5171 a, nor around the normal M-type supergiant μ Cep. We conclude that there is no evidence for high mass loss events prior to 500-1000 years ago for these four stars.
AB - We present high-resolution HST WFPC2 images of compact nebulosity surrounding the cool M-type hypergiants NML Cyg, VX Sgr, and S Per. The powerful OH/IR source NML Cyg exhibits a peculiar bean-shaped asymmetric nebula that is coincident with the distribution of its H 2O vapor masers. We show that NML Cyg's circumstellar envelope is likely shaped by photodissociation from the powerful, nearby association Cyg OB2 inside the Cygnus X superbubble. The OH/IR sources VX Sgr and S Per have marginally resolved envelopes. S Per's circumstellar nebula appears elongated in a northeast/southwest orientation similar to that for its OH and H 2O masers, while VX Sgr is embedded in a spheroidal envelope. We find no evidence for circumstellar nebulosity around the intermediate-type hypergiants ρ Cas, HR 8752, and HR 5171 a, nor around the normal M-type supergiant μ Cep. We conclude that there is no evidence for high mass loss events prior to 500-1000 years ago for these four stars.
KW - Stars: individual (ρ Cassiopeiae, NML Cygni, S Persei, VX Sagittarii)
KW - Supergiants
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U2 - 10.1086/498395
DO - 10.1086/498395
M3 - Article
AN - SCOPUS:31544482701
SN - 0004-6256
VL - 131
SP - 603
EP - 611
JO - Astronomical Journal
JF - Astronomical Journal
IS - 1
ER -