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Title: ANALYSIS OF THE PICO DOS DIAS SURVEY HERBIG Ae/Be CANDIDATES

A large sample of Herbig Ae/Be (HAeBe) candidates, distributed in different Galactic regions south to declination +30 deg., were identified by the Pico dos Dias Survey (a search for young stellar objects based on IRAS colors). Most of the candidates are nearby or associated with star-forming clouds, but several others are considered isolated objects. Aiming to verify the young nature of 93 HAeBe candidates, we searched for additional information that could be useful to confirm if they are pre-main-sequence (PMS) stars or evolved objects, which coincidentally show similar IRAS colors. By adopting a spectral index that is related to the amount of infrared excess and the shape of the spectral energy distribution, we have classified the sample according to three groups, which are analyzed on the basis of (1) circumstellar luminosity; (2) spatial distribution; (3) optical polarization; (4) near-infrared colors; (5) stellar parameters (mass, age, effective temperature); and (5) intensity of emission lines. Our analysis indicates that only 76% of the studied sample, mainly the group with intermediate to low levels of circumstellar emission, can be more confidently considered PMS stars. The nature of the remaining stars, which are in the other group that contains the highest levels of infraredmore » excess, remains to be confirmed. They share the same characteristics of evolved objects, requiring complementary studies in order to correctly classify them. At least seven objects show characteristics typical of post-asymptotic giant branch or proto-planetary nebulae.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Laboratorio Nacional de Astrofisica/MCT, Rua Estados Unidos 154, 37504-364 Itajuba, MG (Brazil)
  2. Universidade de Sao Paulo, IAG, Rua do Matao 1226, 05508-900 Sao Paulo, SP (Brazil)
  3. Instituto Nacional de Pesquisas Espaciais/MCT, Av. dos Astronautas 1758, 12227-010 Sao Jose dos Campos, SP (Brazil)
  4. Fundacao Santo Andre, FAENG, Rua Principe de Gales 821, 09060-650 Santo Andre, SP (Brazil)
  5. Evergreen Valley College, 3095 Yerba Buena Rd., San Jose, CA, 95135 (United States), E-mail: marilia@lna.br
Publication Date:
OSTI Identifier:
21301476
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 139; Journal Issue: 1; Other Information: DOI: 10.1088/0004-6256/139/1/27; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; ASYMPTOTIC SOLUTIONS; EMISSION; ENERGY SPECTRA; LUMINOSITY; MASS; MATTER; PLANETARY NEBULAE; POLARIZATION; SPATIAL DISTRIBUTION; STARS