THE PHYSICAL STRUCTURE OF PROTOPLANETARY DISKS: THE SERPENS CLUSTER COMPARED WITH OTHER REGIONS

Journal Article · Thu Jan 10 04:00:00 EST 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/762/2/128· OSTI ID:22167248

Oliveira, Isa; Van Dishoeck, Ewine F. ^[1]; Merin, Bruno ^[2]

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1. Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)
2. Herschel Science Center, European Space Astronomy Centre (ESA), P.O. Box 78, E-28691 Villanueva de la Canada (Madrid) (Spain)

Spectral energy distributions are presented for 94 young stars surrounded by disks in the Serpens Molecular Cloud, based on photometry and Spitzer/IRS spectra. Most of the stars have spectroscopically determined spectral types. Taking a distance to the cloud of 415 pc rather than 259 pc, the distribution of ages is shifted to lower values, in the 1-3 Myr range, with a tail up to 10 Myr. The mass distribution spans 0.2-1.2 M {sub Sun }, with median mass of 0.7 M {sub Sun }. The distribution of fractional disk luminosities in Serpens resembles that of the young Taurus Molecular Cloud, with most disks consistent with optically thick, passively irradiated disks in a variety of disk geometries (L {sub disk}/L {sub star} {approx} 0.1). In contrast, the distributions for the older Upper Scorpius and {eta} Chamaeleontis clusters are dominated by optically thin lower luminosity disks (L {sub disk}/L {sub star} {approx} 0.02). This evolution in fractional disk luminosities is concurrent with that of disk fractions: with time disks become fainter and the disk fractions decrease. The actively accreting and non-accreting stars (based on H{alpha} data) in Serpens show very similar distributions in fractional disk luminosities, differing only in the brighter tail dominated by strongly accreting stars. In contrast with a sample of Herbig Ae/Be stars, the T Tauri stars in Serpens do not have a clear separation in fractional disk luminosities for different disk geometries: both flared and flat disks present wider, overlapping distributions. This result is consistent with previous suggestions of a faster evolution for disks around Herbig Ae/Be stars. Furthermore, the results for the mineralogy of the dust in the disk surface (grain sizes, temperatures and crystallinity fractions, as derived from Spitzer/IRS spectra) do not show any correlation to either stellar and disk characteristics or mean cluster age in the 1-10 Myr range probed here. A possible explanation for the lack of correlation is that the processes affecting the dust within disks have short timescales, happening repeatedly, making it difficult to distinguish long-lasting evolutionary effects.

• OSTI ID: 22167248
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 762; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
COMPARATIVE EVALUATIONS
CORRELATIONS
COSMIC DUST
DISTANCE
ENERGY SPECTRA
GRAIN SIZE
HERBIG-HARO OBJECTS
LUMINOSITY
MASS DISTRIBUTION
PHOTOMETRY
PROTOPLANETS
STAR CLUSTERS
STAR EVOLUTION
T TAURI STARS