2016A&A...592A..16D


C.D.S. - SIMBAD4 rel 1.7 - 2020.02.21CET11:00:24

2016A&A...592A..16D - Astronomy and Astrophysics, volume 592A, 16-16 (2016/8-1)

Spectral type, temperature, and evolutionary stage in cool supergiants.

DORDA R., NEGUERUELA I., GONZALEZ-FERNANDEZ C. and TABERNERO H.M.

Abstract (from CDS):

Context.In recent years, our understanding of red supergiants has been questioned by strong disagreements between stellar atmospheric parameters derived with different techniques. Temperature scales have been disputed, and the possibility that spectral types do not depend primarily on temperature has been raised.
Aims. We explore the relations between different observed parameters, and we explore the ability to derive accurate intrinsic stellar parameters from these relations through the analysis of the largest spectroscopic sample of red supergiants to date.
Methods. We obtained intermediate-resolution spectra of a sample of about 500 red supergiants in the Large and the Small Magellanic Cloud. From these spectra, we derive spectral types and measure a large set of photospheric atomic lines. We explore possible correlations between different observational parameters, also making use of near- and mid-infrared colours and literature on photometric variability.
Results. Direct comparison between the behaviour of atomic lines (FeI, TiI, and CaII) in the observed spectra and a comprehensive set of synthetic atmospheric models provides compelling evidence that effective temperature is the prime underlying variable driving the spectral-type sequence between early G and M2 for supergiants.In spite of this, there is a clear correlation between spectral type and luminosity, with later spectral types tending to correspond to more luminous stars with heavier mass loss. This trend is much more marked in the LMC than in the SMC. The population of red supergiants in the SMC is characterised by a higher degree of spectral variability, early spectral types (centred on type K1) and low mass-loss rates (as measured by dust-sensitive mid-infrared colours). The population in the LMC displays less spectroscopic variability and later spectral types. The distribution of spectral types is not single-peaked.Instead, the brightest supergiants have a significantly different distribution from less luminous objects, presenting mostly M subtypes (centred on M2), and increasing mass-loss rates for later types.In this regard, the behaviour of red supergiants in the LMC is not very different from that of Milky Way objects.
Conclusions. The observed properties of red supergiants in the SMC and the LMC cannot be described correctly by standard evolutionary models. The very strong correlation between spectral type and bolometric luminosity, supported by all data from the Milky Way, cannot be reproduced at all by current evolutionary tracks.

Abstract Copyright: © ESO, 2016

Journal keyword(s): stars: massive - stars: late-type - supergiants - Magellanic Clouds - stars: evolution

Simbad objects: 20

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Number of rows : 20

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 PMMR 9 s*r 00 45 04.5710389171 -73 05 27.514838586 16.88 14.85 12.84     M1.5Ia 21 0
2 Dachs SMC 1-4 s*r 00 51 03.8625675167 -72 43 17.894540468 14.43 13.264 11.31 10.44   K5-M0Ia 18 0
3 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9230 1
4 NGC 300 GiG 00 54 53.4460065856 -37 41 03.182962667 8.83 8.69 8.13 7.46   ~ 1282 2
5 Cl* NGC 371 LE 29 s*r 01 03 02.4560414762 -72 01 53.000449115 17.09 16.98 14.03 13.48 11.693 K4.5-M4.5Ia-Iab 31 1
6 Ass Per OB 1 As* 02 21 +57.6           ~ 159 1
7 V* S Per s*r 02 22 51.7103845023 +58 35 11.454759954 13.22 10.55 7.90     M4.5-7Iae 352 0
8 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5498 1
9 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14544 1
10 W61 16-80 s*r 05 29 21.5442484788 -68 44 11.097007772   14.2 13.0     K4.5Iab-Ib 11 0
11 SV* HV 2602 s*r 05 30 35.5364772021 -68 59 23.402263732   15.4 13.42 12.50   M5Ia 21 0
12 SV* HV 12998 s*r 05 31 04.1651783318 -69 19 03.040732376 17.846 15.751 14.395 11.81 10.696 M3.5Ia 23 0
13 RM 1-634 s*r 05 34 21.4263659882 -69 22 00.292970280 16.263 14.544 12.776 12.12 11.034 K4.5Iab 15 0
14 V* VY CMa s*r 07 22 58.32877 -25 46 03.2355 12.01 10.19 7.95     M5Iae 987 0
15 V* VX Sgr s*r 18 08 04.0431479808 -22 13 26.629744195 11.72 9.41 6.52 3.90 2.11 M8.5Ia 539 0
16 Cl Stephenson 2 OpC 18 39 20 -06 01.7           ~ 81 0
17 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1417 0
18 NGC 6882 OpC 20 11.8 +26 49     14.1     ~ 69 0
19 NGC 7419 OpC 22 54 20 +60 48.9     13.0     ~ 83 0
20 V* MY Cep s*r 22 54 31.6975860144 +60 49 38.970114015           M7.5I 77 0

    Equat.    Gal    SGal    Ecl

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2020.02.21-11:00:24

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