Open clusters : III. Fundamental parameters of B stars in NGC 6087, NGC 6250, NGC 6383, and NGC 6530 B-type stars with circumstellar envelopes

Context. Stellar physical properties of star clusters are poorly known and the cluster parameters are often very uncertain. Aims. Our goals are to perform a spectrophotometric study of the B star population in open clusters to derive accurate stellar parameters, search for the presence of circumstel...

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Detalles Bibliográficos
Autores principales: Aidelman, Yael Judith, Cidale, Lydia Sonia, Zorec, J., Panei, Jorge Alejandro
Formato: Articulo
Lenguaje:Inglés
Publicado: 2018
Materias:
Astronomía
Be stars
Emission line
Fundamental parameters - Stars
Open clusters and associations
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/93657
https://www.aanda.org/10.1051/0004-6361/201730995
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-93657
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Astronomía
Be stars
Emission line
Fundamental parameters - Stars
Open clusters and associations
spellingShingle Astronomía
Be stars
Emission line
Fundamental parameters - Stars
Open clusters and associations
Aidelman, Yael Judith
Cidale, Lydia Sonia
Zorec, J.
Panei, Jorge Alejandro
Open clusters : III. Fundamental parameters of B stars in NGC 6087, NGC 6250, NGC 6383, and NGC 6530 B-type stars with circumstellar envelopes
topic_facet Astronomía
Be stars
Emission line
Fundamental parameters - Stars
Open clusters and associations
description Context. Stellar physical properties of star clusters are poorly known and the cluster parameters are often very uncertain. Aims. Our goals are to perform a spectrophotometric study of the B star population in open clusters to derive accurate stellar parameters, search for the presence of circumstellar envelopes, and discuss the characteristics of these stars. Methods. The BCD spectrophotometric system is a powerful method to obtain stellar fundamental parameters from direct measurements of the Balmer discontinuity. To this end, we wrote the interactive code MIDE3700. The BCD parameters can also be used to infer the main properties of open clusters: distance modulus, color excess, and age. Furthermore, we inspected the Balmer discontinuity to provide evidence for the presence of circumstellar disks and identify Be star candidates. We used an additional set of high-resolution spectra in the H region to confirm the Be nature of these stars. Results. We provide Te, log g, Mv, Mbol, and spectral types for a sample of 68 stars in the field of the open clusters NGC6087, NGC6250, NGC6383, and NGC6530, as well as the cluster distances, ages, and reddening. Then, based on a sample of 230 B stars in the direction of the 11 open clusters studied along this series of three papers, we report 6 new Be stars, 4 blue straggler candidates, and 15 B-type stars (called Bdd) with a double Balmer discontinuity, which indicates the presence of circumstellar envelopes. We discuss the distribution of the fraction of B, Be, and Bdd star cluster members per spectral subtype. The majority of the Be stars are dwarfs and present a maximum at the spectral type B2-B4 in young and intermediate-age open clusters (<40 Myr). Another maximum of Be stars is observed at the spectral type B6-B8 in open clusters older than 40 Myr, where the population of Bdd stars also becomes relevant. The Bdd stars seem to be in a passive emission phase. Conclusions. Our results support previous statements that the Be phenomenon is present along the whole main sequence band and occurs in very dierent evolutionary states.We find clear evidence of an increase of stars with circumstellar envelopes with cluster age. The Be phenomenon reaches its maximum in clusters of intermediate age (10-40 Myr) and the number of B stars with circumstellar envelopes (Be plus Bdd stars) is also high for the older clusters (40-100 Myr).
format Articulo
Articulo
author Aidelman, Yael Judith
Cidale, Lydia Sonia
Zorec, J.
Panei, Jorge Alejandro
author_facet Aidelman, Yael Judith
Cidale, Lydia Sonia
Zorec, J.
Panei, Jorge Alejandro
author_sort Aidelman, Yael Judith
title Open clusters : III. Fundamental parameters of B stars in NGC 6087, NGC 6250, NGC 6383, and NGC 6530 B-type stars with circumstellar envelopes
title_short Open clusters : III. Fundamental parameters of B stars in NGC 6087, NGC 6250, NGC 6383, and NGC 6530 B-type stars with circumstellar envelopes
title_full Open clusters : III. Fundamental parameters of B stars in NGC 6087, NGC 6250, NGC 6383, and NGC 6530 B-type stars with circumstellar envelopes
title_fullStr Open clusters : III. Fundamental parameters of B stars in NGC 6087, NGC 6250, NGC 6383, and NGC 6530 B-type stars with circumstellar envelopes
title_full_unstemmed Open clusters : III. Fundamental parameters of B stars in NGC 6087, NGC 6250, NGC 6383, and NGC 6530 B-type stars with circumstellar envelopes
title_sort open clusters : iii. fundamental parameters of b stars in ngc 6087, ngc 6250, ngc 6383, and ngc 6530 b-type stars with circumstellar envelopes
publishDate 2018
url http://sedici.unlp.edu.ar/handle/10915/93657
https://www.aanda.org/10.1051/0004-6361/201730995
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