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Titolo:
Near-infrared imaging of compact HII regions in Cygnus X
Autore:
Comeron, F; Torra, J;
Indirizzi:
European So Observ, D-85748 Garching, Germany European So Observ Garching Germany D-85748 v, D-85748 Garching, Germany Univ Barcelona, Dept Astron & Meteorol, E-08028 Barcelona, Spain Univ Barcelona Barcelona Spain E-08028 eteorol, E-08028 Barcelona, Spain
Titolo Testata:
ASTRONOMY & ASTROPHYSICS
fascicolo: 2, volume: 375, anno: 2001,
pagine: 539 - 552
SICI:
1432-0746(200108)375:2<539:NIOCHR>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
H-II REGIONS; YOUNG STELLAR OBJECTS; LUMINOUS IRAS SOURCES; STAR-FORMING REGIONS; MOLECULAR CLOUDS; MASER EMISSION; SPECTRAL CLASSIFICATION; VLA OBSERVATIONS; OB ASSOCIATIONS; POINT SOURCES;
Keywords:
stars : early-type; HII regions; Cygnus X;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
70
Recensione:
Indirizzi per estratti:
Indirizzo: Comeron, F European So Observ, Karl Schwarzschild Str 2, D-85748 Garching,Germany European So Observ Karl Schwarzschild Str 2 Garching Germany D-85748
Citazione:
F. Comeron e J. Torra, "Near-infrared imaging of compact HII regions in Cygnus X", ASTRON ASTR, 375(2), 2001, pp. 539-552

Abstract

We present a near-infrared imaging survey of compact HII regions in the direction of the Cygnus X complex, for which no previous observations at those wavelengths have been published so far. The targets have been selected from a catalog of sources in that region having a thermal spectral energy distribution between 408 and 4800 MHz (Wendker et al. 1991), and an inferred angular size smaller than 5 arcmin across. We present images in the JHK filters, color-magnitude, and color-color diagrams for each region. We also suggest and apply a method for estimating the distance by comparing the dereddened H-band flux from all the stars in the area of the HII region and the radio-continuum flux. Many of the regions imaged are clearly associated withstellar aggregates with different degrees of concentration, whose components show varying amounts of extinction. Some objects are often found in the region of the (J-H), (H-K) diagram indicating excess emission of circumstellar nature. A detailed discussion on each object is provided in the contextof existing published observations at different wavelengths, in particularregarding the existence of ultracompact components. A number of ultracompact HII regions are found to have clearly visible unresolved or nearly unresolved K-band counterparts characterized by very red H-K colors, suggesting that the extinction may be low enough in their direction so as to allow thedirect observation of the star ionizing the ultracompact component.

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Documento generato il 05/04/20 alle ore 02:35:16