Titre du document / Document title
Carina's defiant finger: HST observations of a photoevaporating globule in NGC 3372
Auteur(s) / Author(s)
SMITH Nathan (1) ;
BARBA Rodolfo H. (2) ;
WALBORN Nolan R. (3) ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309, ETATS-UNIS
(2) Departmento de Fisica, Universidad de La Serena, Benavente 980, La Serena, CHILI
(3) Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, ETATS-UNIS
Résumé / Abstract
We present Hubble Space Telescope Wide Field Planetary Camera 2 images of a prominent externally ionized molecular globule in the Carina Nebula (NGC 3372), supplemented with ground-based infrared images and visual-wavelength spectra. This molecular globule has a shape resembling a human hand, with an extended finger that points toward its likely source of ionizing radiation. Following an analysis of the spatially resolved ionization structure and spectrum of the photoevaporative flow from the Finger, we conclude that the dominant ionizing source is either the WNL star WR25 (HD 93162), the adjacent 04 If-type star Trl6-244, or perhaps both. We estimate a mass-loss rate of ∼2 x 10
-5 M
○. yr
-1 from the main evaporating surface of the globule, suggesting a remaining lifetime of 10
5.3-10
6 yr. We find a total mass for the entire globule of more than 6 M
○., in agreement with previous estimates. The hydrogen column density through the globule derived from extinction measurements is a few times 10
22 cm
-2, so the photodissociation region behind the ionization front should be limited to a thin layer compared to the size of the globule, in agreement with the morphology seen in H
2 images. Although a few reddened stars are seen within the boundary of the globule in near-infrared continuum images, these may be background stars. We do not detect a reddened star at the apex of the finger, for example, down to a limiting magnitude of m
K ≃ 17. However, considering the physical properties of the globule and the advancing ionization front, it appears that future star formation is likely in the Finger globule, induced by radiation-driven implosion.
Revue / Journal Title
Monthly notices of the Royal Astronomical Society
ISSN
0035-8711
CODEN MNRAA4
Source / Source
2004, vol. 351, n
o4, pp. 1457-1470 [14 page(s) (article)] (49 ref.)
Langue / Language
Anglais
Editeur / Publisher
Wiley-Blackwell, Malden, MA, ETATS-UNIS
(1833)
(Revue)
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Localisation / Location
INIST-CNRS, Cote INIST : 2067, 35400012004637.0310
Nº notice refdoc (ud4) : 15915269
