OBSERVATIONS OF A HIGH-MASS PROTOSTAR IN NGC 7538 S

Journal Article · Mon Feb 20 04:00:00 EST 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/746/2/187· OSTI ID:22011665

Wright, Melvyn ^[1]; Junui, Zhao ^[2]; Sandell, Goeran ^[3]; Corder, Stuartt ^[4]; Goss, W M ^[5]; Lei, Zhu ^[6]

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1. Radio Astronomy Laboratory, University of California, Berkeley 601 Campbell Hall, Berkeley, CA 94720 (United States)
2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
3. NASA Ames Research Center, SOFIA-USRA, Mail Stop 211-3, Building N211, Rm. 249, P.O. Box 1, Moffett Field, CA 94035-0001 (United States)
4. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
5. National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States)
6. Department of Astronomy, Peking University, Beijing 100871 (China)

We present high angular resolution continuum observations of the high-mass protostar NGC 7538 S with BIMA and CARMA at 3 and 1.4 mm, Very Large Array (VLA) observations at 1.3, 2, 3.5, and 6 cm, and archive Infrared Array Camera (IRAC) observations from the Spitzer Space Observatory, which detect the star at 4.5, 5.8, and 8 {mu}m. The star looks rather unremarkable in the mid-IR. The excellent positional agreement of the IRAC source with the VLA free-free emission, the OH, CH{sub 3}OH, H{sub 2}O masers, and the dust continuum confirms that this is the most luminous object in the NGC 7538 S core. The continuum emission at millimeter wavelengths is dominated by dust emission from the dense cold cloud core surrounding the protostar. Including all array configurations, the emission is dominated by an elliptical source with a size of {approx}8'' Multiplication-Sign 3''. If we filter out the extended emission we find three compact millimeter sources inside the elliptical core. The strongest one, S{sub A}, coincides with the VLA/IRAC source and resolves into a double source at 1.4 mm, where we have subarcsecond resolution. The measured spectral index, {alpha}, between 3 and 1.4 mm is {approx}2.3, and steeper at longer wavelengths, suggesting a low dust emissivity or that the dust is optically thick. We argue that the dust in these accretion disks is optically thick and estimate a mass of an accretion disk or infalling envelope surrounding S{sub A} to be {approx}60 M{sub Sun }.

• OSTI ID: 22011665
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 746; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
DUSTS
EMISSIVITY
MASERS
METHANOL
STAR EVOLUTION
STARS