Infrared Studies Of Pre-Main-Sequence Intermediate-Mass Stars - Lkh-Alpha-198

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dc.contributor.utaustinauthorEvans, Neal J.en_US
dc.contributor.utaustinauthorHarvey, Paul M.en_US
dc.creatorNatta, Antonellaen_US
dc.creatorPalla, Franciscoen_US
dc.creatorButner, Harold M.en_US
dc.creatorEvans, Neal J.en_US
dc.creatorHarvey, Paul M.en_US
dc.date.accessioned2016-04-28T19:36:59Z
dc.date.available2016-04-28T19:36:59Z
dc.date.issued1992-06en
dc.description.abstractFar-infrared scans of LkH-alpha 198 at 50 and 100-mu-m along several directions reveal an extended, roughly spherical source with an average FWHM of 33" or 2 x 10(4) AU at 100-mu-m and up to 18" or 1.5 x 10(4) AU at 50-mu-m. By comparing the observed properties at optical, infrared, and millimeter wavelengths with the predictions of radiation transfer models, we estimate a luminosity of 250 L. at a distance of 600 pc. The optical depth at 100-mu-m is 0.004-0.006, implying a mass of approximately 2 M. within a radius of 10(4) AU. The dust configuration is characterized by a power-law distribution n(r) approximately r-alpha, with alpha-approximately 0.5, in most of the directions around the star and over large distances. The inner radius of the dusty envelope is probably rather small, r(i) less-than-or-similar-to 300 AU (0".5), and it may be as small as the dust destruction front: in LkH-alpha 198 there is no evidence of a large region devoid of grains. The fit to the observed spectral energy distribution (SED) from optical to millimeter wavelengths favors a model that includes a disk and a spherical envelope. The former is required in order to provide a good match to the SED at near-infrared wavelengths. The disk mass is 0.27 M., i.e., approximately 7% of the stellar mass. Alternatively, the SED can be fitted by a spherical dust envelope only, if there is a component of very small grains and polycyclic aromatic hydrocarbons. Within the current scenario of star formation, mostly developed for solar-mass stars, it is not easy to account for the flat density profile of the dusty envelope we observe around LkH-alpha 198.en_US
dc.description.departmentAstronomyen_US
dc.description.sponsorshipNASA NAG2-420, NAG2-67en_US
dc.description.sponsorshipASI PSN-87-039, ASI-90-RS-46en_US
dc.identifierdoi:10.15781/T2F817
dc.identifier.Filename1992_06_infraredstudies.pdfen_US
dc.identifier.citationNatta, Antonella, Francesco Palla, Harold M. Butner, Neal J. Evans, and Paul M. Harvey. "Infrared studies of pre-main-sequence intermediate-mass stars-LkHalpha 198." The Astrophysical Journal, Vol. 391 (Jun., 1992): 805-816.en_US
dc.identifier.doi10.1086/171389en_US
dc.identifier.issn0004-637Xen_US
dc.identifier.urihttp://hdl.handle.net/2152/34916
dc.language.isoEnglishen_US
dc.relation.ispartofen_US
dc.relation.ispartofserialAstrophysical Journalen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.rights.restrictionOpenen_US
dc.subjectcircumstellar matteren_US
dc.subjectinfrared, starsen_US
dc.subjectstars, individualen_US
dc.subject(lkh-alpha-198)en_US
dc.subjectstars, pre-main-sequenceen_US
dc.subjectt-tauri starsen_US
dc.subjectyoung stellar objectsen_US
dc.subjectlkh-alpha 198en_US
dc.subjectmolecular cloudsen_US
dc.subjectinterstellar matteren_US
dc.subjectiras observationsen_US
dc.subjectherbig aeen_US
dc.subjectdusten_US
dc.subjectemissionen_US
dc.subjectspectraen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleInfrared Studies Of Pre-Main-Sequence Intermediate-Mass Stars - Lkh-Alpha-198en_US
dc.typeArticleen_US

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