THE BRIGHTENING OF Re50N: ACCRETION EVENT OR DUST CLEARING?

ABSTRACT The luminous Class I protostar HBC 494, embedded in the Orion A cloud, is associated with a pair of reflection nebulae, Re50 and Re50N, which appeared sometime between 1955 and 1979. We have found that a dramatic brightening of Re50N has taken place sometime between 2006 and 2014. This coul...

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Bibliographic Details
Published in:The Astrophysical journal 2015-05, Vol.805 (1), p.1-5
Main Authors: Chiang, Hsin-Fang, Reipurth, Bo, Walawender, Josh, Connelley, Michael S., Pessev, Peter, Geballe, T. R., Best, William M. J., Paegert, Martin
Format: Article
Language:English
Subjects:
ABSORPTION
Accretion
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Brightening
CARBON MONOXIDE
CLOUDS
ERUPTION
Fading
HERBIG-HARO OBJECTS
ILLUMINANCE
INFRARED SPECTRA
LUMINOSITY
MASS
Molecular clouds
NEAR INFRARED RADIATION
NEBULAE
Orion nebula
PROTOSTARS
REFLECTION
STARS
stars: formation
stars: low-mass
stars: pre-main sequence
stars: protostars
SURFACES
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Summary:ABSTRACT The luminous Class I protostar HBC 494, embedded in the Orion A cloud, is associated with a pair of reflection nebulae, Re50 and Re50N, which appeared sometime between 1955 and 1979. We have found that a dramatic brightening of Re50N has taken place sometime between 2006 and 2014. This could result if the embedded source is undergoing a FUor eruption. However, the near-infrared spectrum shows a featureless very red continuum, in contrast to the strong CO bandhead absorption displayed by FUors. Such heavy veiling, and the high luminosity of the protostar, is indicative of strong accretion but seemingly not in the manner of typical FUors. We favor the alternative explanation that the major brightening of Re50N and the simultaneous fading of Re50 is caused by curtains of obscuring material that cast patterns of illumination and shadows across the surface of the molecular cloud. This is likely occurring as an outflow cavity surrounding the embedded protostar breaks through to the surface of the molecular cloud. Several Herbig-Haro objects are found in the region.
ISSN:0004-637X
1538-4357
1538-4357
DOI:10.1088/0004-637X/805/1/54