2006A&A...454..609M


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.15CEST08:25:03

2006A&A...454..609M - Astronomy and Astrophysics, volume 454, 609-615 (2006/8-1)

Modelling chromospheric line profiles in NGC 2808: evidence of mass loss from RGB stars.

MAUAS P.J.D., CACCIARI C. and PASQUINI L.

Abstract (from CDS):

In this study we test the possibility that the asymmetry in the profiles of the Hα and Ca II K lines in red giant stars is due to the presence of an active chromosphere rather than to mass loss. To this end, we compare line profiles computed using relevant model chromospheres to profiles of the Hα and Ca II K lines observed in five red giant stars of the globular cluster NGC 2808. The spectra were taken with FLAMES during the science verification, using the UVES mode at high resolution (R=43000) for the Hα line, and GIRAFFE in MEDUSA mode (R=20000) for the Ca II K line. We find that the observed profiles are better described if a negative (outward) velocity field is included in the model chromospheres. This leads to mass loss rates of a few 10–9M/yr, so very close to the requirements of the stellar evolution theory.

Abstract Copyright:

Journal keyword(s): line: profiles - globular clusters: individual: NGC 2808 - stars: atmospheres - stars: mass loss - stars: Population II - techniques: spectroscopic

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 2MASS J09120227-6451184 LP* 09 12 02.28 -64 51 18.4   15.1 13.49   11.64 ~ 11 0
2 IRAS 09110-6439 GlC 09 12 03.10 -64 51 48.6   7.77 5.69     ~ 1245 0
3 Cl* NGC 2808 PKD 47606 * 09 12 06.6571 -64 52 18.225   15.257 13.436     ~ 9 0
4 Cl* NGC 2808 PKD 51499 * 09 12 07.36 -64 51 17.7   15.157 13.435     ~ 9 0
5 2MASS J09120851-6451583 LP* 09 12 08.51 -64 51 58.4   15.15 13.62   11.69 ~ 12 0
6 2MASS J09122307-6456341 RG* 09 12 23.0717455156 -64 56 34.288396463   15.345 13.737   12.048 ~ 10 0
7 M 13 GlC 16 41 41.634 +36 27 40.75     5.8     ~ 2007 0

    Equat.    Gal    SGal    Ecl

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2020.07.15-08:25:03

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