J/AJ/157/167 Equivalent widths for RSGs in the MW & LMC/SMC (Dicenzo+, 2019)
Atomic absorption line diagnostics for the physical properties of red
supergiants.
Dicenzo B., Levesque E.M.
<Astron. J., 157, 167-167 (2019)>
=2019AJ....157..167D 2019AJ....157..167D (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Magellanic Clouds ; Stars, late-type ;
Stars, supergiant ; Spectral types ; Effective temperatures ;
Equivalent widths
Keywords: stars: atmospheres - stars: fundamental parameters -
stars: late-type - supergiants
Abstract:
Red supergiants (RSGs) are evolved massive stars that represent extremes,
in both their physical sizes and their cool temperatures, of the massive
star population. The effective temperature (Teff) is the most critical
physical property needed to place an RSG on the Hertzsprung-Russell
Diagram, due to the stars' cool temperatures and resulting large bolometric
corrections. Several recent papers have examined the potential utility
of atomic line equivalent widths (EWs) in cool supergiant (CSG) spectra
for determining Teff and other physical properties and found strong
correlations between Ti I and Fe I spectral features and Teff in
earlier-type CSGs (G and early K) but poor correlations in M-type stars,
a spectral subtype that makes up a significant fraction of RSGs. We have
extended this work by measuring the EWs of Ti, Fe, and Ca lines in late K-
and M-type RSGs in the Milky Way, Large Magellanic Cloud, and Small
Magellanic Cloud, and compared these results to the predictions of the
theoretical stellar LTE atmosphere models (MARCS) stellar atmosphere
models. Our analyses show a poor correlation between Teff and the Fe I
and Ti I lines in our observations (at odds with strong correlations
predicted by stellar atmosphere models), but do find statistically
significant correlations between Teff and the Ca II triplet (CaT)
features of Milky Way RSGs, suggesting that this could be a potential
diagnostic tool for determining Teff in M-type supergiants. We also
examine correlations between these spectral features and other physical
properties of RSGs (including metallicity, surface gravity, and bolometric
magnitude), and consider the underlying physics driving the evolution
of atomic line spectra in RSGs.
Description:
The RSG echelle spectra used in these analyses were originally observed
as part of a spectroscopic search for potential Thorne-Zytkow objects
in the Milky Way and Magellanic Clouds (Levesque et al.
2014MNRAS.443L..94L 2014MNRAS.443L..94L). The sample of 25 Milky Way stars was selected
from the coldest RSGs identified in Levesque et al. (2005ApJ...628..973L 2005ApJ...628..973L),
all having spectral types of K5-M0I or later. The spectra were observed
using the Astrophysics Research Consortium Echelle Spectrograph
(Wang et al. 2003SPIE.4841.1145W 2003SPIE.4841.1145W) on the Apache Point Observatory 3.5 m
telescope on 2011 February 11 and 12 (UT). Our Magellanic Cloud sample
was drawn from late-type RSGs identified in Levesque et al.
(2006ApJ...645.1102L 2006ApJ...645.1102L) and supplemented by additional stars with broadband
colors consistent with RSGs (for a complete discussion see Levesque et al.
2014MNRAS.443L..94L 2014MNRAS.443L..94L). These stars were observed with the Magellan Inamori
Kyocera Echelle (Bernstein et al. 2003SPIE.4841.1694B 2003SPIE.4841.1694B) on the Magellan
6.5 m at Las Campanas Observatory during 2011 September 13-15.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 79 58 Sample stars
table3.dat 52 58 Ca I and CaT equivalent widths
table4.dat 100 58 Fe I equivalent widths
table5.dat 58 58 Ti I equivalent widths
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See also:
J/AJ/126/2867 : Red supergiants in Magellanic Clouds (Massey+, 2003)
J/ApJ/749/177 : Yellow and red supergiants in the LMC (Neugent+, 2012)
J/ApJ/751/156 : Ti and Fe lines in red supergiants (Bergemann+, 2012)
J/ApJ/754/35 : Red supergiant stars in the SMC. II. (Yang+, 2012)
J/MNRAS/427/3209 : Galactic and MC O-AGBs and RSGs stars (Jones+, 2012)
J/ApJ/822/L5 : Observed red supergiants in the inner Galaxy
(Messineo+, 2016)
J/A+A/616/A175 : Red supergiant stars in the LMC. II. (Yang+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Gal Galaxy name
11- 27 A17 --- Star Star name
29- 35 A7 --- SpType Spectral type
37- 40 I4 K Teff [3425/3900] Effective temperature
42- 45 F4.1 [cm/s2] b_logg [-0.7/0.6]? Surface gravity, lower value
47- 50 F4.1 [cm/s2] B_logg [-0.4]? Surface gravity, upper value
52- 56 F5.2 mag b_Mbol [-9.64/-5.77]? Bolometric luminosity, lower
value
58- 62 F5.2 mag B_Mbol [-8.57]? Bolometric luminosity, upper value
64- 79 A16 --- Assoc Name of OB association(s)
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Gal Galaxy name
11- 27 A17 --- Star Star name
29- 34 F6.4 0.1nm EW(6572) [0.285/0.43] Equivalent width of Ca I 6572Å
(Å)
36- 40 F5.3 0.1nm EW(8498) [1.44/2.85] Equivalent width of Ca II 8498Å
(Å)
42- 46 F5.3 0.1nm EW(8542) [1.76/5.29] Equivalent width of Ca II 8542Å
(Å)
48- 52 F5.3 0.1nm EW(8662) [2.34/4.5] Equivalent width of Ca II 8662Å
(Å)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Gal Galaxy name
11- 27 A17 --- Star Star name
29- 33 F5.3 0.1nm EW(8514.1) [0.19/1.103] Equivalent width of
Fe I 8514.1Å (Å)
35- 39 F5.3 0.1nm EW(8582.0) [0.094/0.455] Equivalent width of
Fe I 8582.0Å (Å)
41- 45 F5.3 0.1nm EW(8611.0) [0.069/0.501] Equivalent width of
Fe I 8611.0Å (Å)
47- 51 F5.3 0.1nm EW(8679.4) [0.021/0.087] Equivalent width of
Fe I 8679.4Å (Å)
53- 57 F5.3 0.1nm EW(8688.5) [0.361/1.205] Equivalent width of
Fe I 8688.5Å (Å)
59- 63 F5.3 0.1nm EW(8710.2) [0.012/0.283] Equivalent width of
Fe I 8710.2Å (Å)
65- 70 F6.4 0.1nm EW(8712.8) [0.091/0.546] Equivalent width of
Fe I 8712.8Å (Å)
72- 76 F5.3 0.1nm EW(8757.0) [0.222/0.609] Equivalent width of
Fe I 8757.0Å (Å)
78- 82 F5.3 0.1nm EW(8793.2) [0.162/0.475] Equivalent width of
Fe I 8793.2Å (Å)
84- 88 F5.3 0.1nm EW(8805.0) [0.212/0.803] Equivalent width of
Fe I 8805.0Å (Å)
90- 94 F5.3 0.1nm EW(8824.0) [0.342/1.438] Equivalent width of
Fe I 8824.0Å (Å)
96-100 F5.3 0.1nm EW(8838.0) [0.03/1.031] Equivalent width of
Fe I 8838.0Å (Å)
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Gal Galaxy name
11- 27 A17 --- Star Star name
29- 33 F5.3 0.1nm EW(8518.1) [0.055/0.543] Equivalent width of
Ti I 8518.1Å (Å)
35- 39 F5.3 0.1nm EW(8683.0) [0.201/0.701] Equivalent width of
Ti I 8683.0Å (Å)
41- 46 F6.4 0.1nm EW(8692.0) [0.168/0.463] Equivalent width of
Ti I 8692.0Å (Å)
48- 52 F5.3 0.1nm EW(8730.5) [0.011/0.212] Equivalent width of
Ti I 8730.5Å (Å)
54- 58 F5.3 0.1nm EW(8734.5) [0.055/0.362] Equivalent width of
Ti I 8734.5Å (Å)
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 17-Jul-2019