Evolution of the Dust/Gas Environment around Herbig Ae/Be Stars

Using the KOSMA 3 m telescope, 54 Herbig Ae/Be (HAe/Be) stars were surveyed in CO and 13CO emission lines. The properties of the stars and their circumstellar environments were studied by fitting spectral energy distributions (SEDs). The mean line width of 13CO (2--1) lines of this sample is 1.87 km...

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Bibliographic Details
Published in:The Astrophysical journal 2011-06, Vol.734 (1), p.22-jQuery1323907606770='48'
Main Authors: Liu, Tie, Zhang, Huawei, Wu, Yuefang, Qin, Sheng-Li, Miller, Martin
Format: Article
Language:English
Subjects:
Age
Astronomy
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CARBON 13
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CORRELATIONS
DENSITY
Disks
DUSTS
Earth, ocean, space
ELEMENTS
EMISSION
ENERGY SPECTRA
Envelopes
EVEN-ODD NUCLEI
EVOLUTION
Exact sciences and technology
HYDROGEN
Infrared
ISOTOPES
LIGHT NUCLEI
LINE WIDTHS
MASS
NONMETALS
NUCLEI
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SPECTRA
Spectral energy distribution
STABLE ISOTOPES
STAR EVOLUTION
STARS
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Summary:Using the KOSMA 3 m telescope, 54 Herbig Ae/Be (HAe/Be) stars were surveyed in CO and 13CO emission lines. The properties of the stars and their circumstellar environments were studied by fitting spectral energy distributions (SEDs). The mean line width of 13CO (2--1) lines of this sample is 1.87 km s--1. The average column density of H2 is found to be 4.9 X 1021 cm--2 for stars younger than 106 yr, while this drops to 2.5 X 1021 cm--2 for those older than 106 yr. No significant difference is found among the SEDs of HAe and HBe stars of the same age. Infrared excess decreases with age, envelope masses and envelope accretion rates decease with age after 105 yr, the average disk mass of the sample is 3.3 X 10--2 M , the disk accretion rate decreases more slowly than the envelope accretion rate, and a strong correlation between the CO line intensity and the envelope mass is found.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/734/1/22