EVIDENCE FOR AN EDGE-ON DISK AROUND THE YOUNG STAR MWC 778 FROM INFRARED IMAGING AND POLARIMETRY

Journal Article · Fri May 15 04:00:00 EDT 2009 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/137/5/4468; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21269179

Perrin, Marshall D ^[1]; Vacca, William D ^[2]

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1. Division of Astronomy, University of California, Los Angeles, CA 90095 (United States)
2. SOFIA-USRA, NASA Ames Research Center, Moffett Field, CA 94035 (United States)

MWC 778 is an unusual and little-studied young stellar object located in the IC 2144 nebula. Recent spectroscopy by Herbig and Vacca suggested the presence of an edge-on circumstellar disk around it. We present near-infrared adaptive optics imaging polarimetry and mid-infrared imaging which directly confirm the suspected nearly edge-on disk around MWC 778 (i {approx} 70{sup 0}-80{sup 0}) plus reveal a more extensive envelope pierced by bipolar outflow cavities. In addition, our mid-infrared images and near-infrared polarization maps detect a spiral-shaped structure surrounding MWC 778, with arms that extend beyond 6'' on either side of the star. Although MWC 778 has previously been classified as a Herbig Ae/Be star, the properties of its central source (including its spectral type) remain fairly uncertain. Herbig and Vacca suggested an F or G spectral type based on the presence of metallic absorption lines in the optical spectrum, which implies that MWC 778 may belong to the fairly rare class of intermediate-mass T Tauri Stars (IMTTSs) which are the evolutionary precursors to Herbig Ae/Be objects. Yet its integrated bolometric luminosity, {approx}>750 L {sub sun} (for an assumed distance of 1 kpc) is surprisingly high for an F or G spectral type, even for an IMTTS. We speculate on several possible explanations for this discrepancy, including its true distance being much closer than 1 kpc, the presence of a binary companion, and/or a nonstellar origin for the observed absorption lines.

• OSTI ID: 21269179
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 5 Vol. 137; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
ABSORPTION
BOLOMETERS
DISTANCE
IMAGES
LUMINOSITY
MAPS
MASS
MATTER
NEBULAE
POLARIMETRY
POLARIZATION
SPECTROSCOPY
T TAURI STARS