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The Identification of New Be Stars in GAUDI
The Ground-based Asteroseismology Uniform Database Interface (GAUDI) isthe result of the preparatory work performed for the COROT satellite. Inthe data available in GAUDI we discovered 17 B-type stars that showemission in their Balmer lines and were not known to display suchemission before, including at least 16 nonsupergiant ones. We thusreclassify those stars as Be stars. These 17 new Be stars increase thenumber of Be stars in the field of view of COROT by ~25%, which isimportant for the target selection of the mission. Moreover, ~70% of thediscovered Be stars are of late subtypes. Be stars have been mostlyfound among early subtypes until now, but this could be due to anobservational bias. Finally, one of the discovered stars is either aslowly rotating shell Be star or a Herbig Be star with a low vsini,which makes this star especially interesting.Based on GAUDI, the data archive and access system of the ground-basedasteroseismology programme of the COROT mission. The GAUDI system ismaintained at LAEFF (http://ines.laeff.esa.es/corot/). LAEFF is part ofthe Space Science Division of INTA.
| Herbig Ae/Be Stars in nearby OB Associations
We have carried out a study of the early-type stars in nearby OBassociations spanning an age range of ~3-16 Myr, with the aim ofdetermining the fraction of stars that belong to the Herbig Ae/Be class.We studied the B, A, and F stars in the nearby (<=500 pc) OBassociations Upper Scorpius, Perseus OB2, Lacerta OB1, and Orion OB1,with membership determined from Hipparcos data. We also included in ourstudy the early-type stars in the Trumpler 37 cluster, part of the CepOB2 association. We obtained spectra for 440 Hipparcos stars in theseassociations, from which we determined accurate spectral types, visualextinctions, effective temperatures, luminosities and masses, usingHipparcos photometry. Using colors corrected for reddening, we find thatthe Herbig Ae/Be stars and the classical Be (CBe) stars occupy clearlydifferent regions in the JHK diagram. Thus, we use the location on theJHK diagram, as well as the presence of emission lines and of strong 12μm flux relative to the visual, to identify the Herbig Ae/Be stars inthe associations. We find that the Herbig Ae/Be stars constitute a smallfraction of the early-type stellar population even in the youngerassociations. Comparing the data from associations with different agesand assuming that the near-infrared excess in the Herbig Ae/Be starsarises from optically thick dusty inner disks, we determined theevolution of the inner disk frequency with age. We find that the innerdisk frequency in the age range 3-10 Myr in intermediate-mass stars islower than that in the low-mass stars (<1 Msolar) inparticular, it is a factor of ~10 lower at ~3 Myr. This indicates thatthe timescales for disk evolution are much shorter in theintermediate-mass stars, which could be a consequence of more efficientmechanisms of inner disk dispersal (viscous evolution, dust growth, andsettling toward the midplane).
| Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
| An Analysis of the Hauck / Mermilliod Catalogue of Homgeneous Four-Color Data - Part Two
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&AS...40..199P&db_key=AST
| A photometric study of the Orion OB 1 association. III - Subgroup analyses
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978ApJS...36..497W&db_key=AST
| A photometric study of the Orion OB 1 association. I - Observational data.
A catalog of observational data is presented for stars in the region ofthe young stellar association Orion OB 1. Photoelectric observationsobtained in the uvby-beta and UBV systems are compiled along withprevious photoelectric and spectroscopic data for all these stars aswell as for several bright members of the association with availablephotometric indices. Mean weighted values are computed for thephotometric data and summarized in tables expected to be reasonablycomplete for association members earlier than spectral type A0.Membership criteria are derived, and qualitative membershipprobabilities summarized, for the 526 stars in the final program. Theanalytical procedures are discussed for association stars of B,intermediate, and AF types. Effects of the nebular environment andvarious calibrations of Balmer-line and four-color indices areconsidered for the determination of absolute magnitudes for the B-typestars.
| M 78 : an active region of star formation in the dark cloud LYNDS 1630.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975ApJ...196..489S&db_key=AST
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| Takýmyýldýz: | Avci |
| Sað Açýklýk: | 05h48m45.97s |
| Yükselim: | +00°43'32.0" |
| Görünürdeki Parlaklýk: | 7.214 |
| Uzaklýk: | 268.097 parsek |
| özdevim Sað Açýklýk: | -4 |
| özdevim Yükselim: | -0.1 |
| B-T magnitude: | 7.063 |
| V-T magnitude: | 7.202 |
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