Spitzer, Very Large Telescope, and Very Large Array observations of the Galactic luminous blue variable candidate HD 168625

Journal
Date Issued
2010
Author(s)
•
•
•
•
Hora, J.L.
DOI
Abstract
We present mid-IR and radio observations of the Galactic luminous blue variables (LBVs) candidate HD 168625 and its associated nebula.We obtained mid-IR spectroscopic observations using the Infrared Spectrograph on board the Spitzer Space Telescope, and performed mid-IR and radio imaging observations using VISIR on the Very Large Telescope and the Very Large Array with comparable angular resolution. Our spectroscopic observations detected spectral features attributable to polycyclic aromatic hydrocarbons (PAHs) and therefore indicate the presence of a photodissociation region (PDR) around the ionized nebula. This result increases the number of LBVs and LBV candidates where a PDR has been found, confirming the importance of such a component in the total mass-loss budget of the central object during this elusive phase of massive star evolution. We have analyzed and compared the mid-IR and radio maps, and derive several results concerning the associated nebula. There is evidence for grain distribution variations across the nebula, with a predominant contribution from bigger grains in the northern part of the nebula while PAH and smaller grains are more concentrated in the southern part. A compact radio component located where there is a lack of thermal dust grains corroborates the presence of a shock in the southern nebula, which could arise as a consequence of the interaction of a fast outflow with the slower, expanding dusty nebula. Such a shock would be a viable means for PAH production as well as for changes in the grain size distribution. Finally, from the detection of a central radio component probably associated with the wind from the central massive supergiant, we derive a current mass-loss rate of ?M = (1.46 ± 0.15) × 10 -6M⊙ yr-1. © 2010. The American Astronomical Society. All rights reserved.
Volume
718
Issue
2
Start page
1036-1045
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2010ApJ...718.1036U
Rights
open.access
File(s)
Loading...
Thumbnail Image
Name

Umana_2010_ApJ_718_1036.pdf

Description
Pdf editoriale
Size

1.61 MB

Format

Adobe PDF

Checksum (MD5)

7a16e61faaf1583c3a34cfddadb21d11