J/A+A/571/A43 Candidate red supergiants in Galactic clusters (Messineo+, 2014)
Near-infrared spectroscopy of candidate red supergiant stars in clusters.
Messineo M., Zhu Q.F., Ivanov V.D., Figer D.F., Davies B., Menten K.M.,
Kudritzki R.P., Chen C.-H.R.
<Astron. Astrophys., 571, A43-43 (2014)>
=2014A&A...571A..43M 2014A&A...571A..43M
ADC_Keywords: Associations, stellar ; Stars, supergiant ; Photometry ;
Equivalent widths
Keywords: stars: mass-loss - dust, extinction - supergiants - stars: late-type -
Galaxy: stellar content
Abstract:
Clear identifications of Galactic young stellar clusters farther than
a few kpc from the Sun are rare, despite the large number of candidate
clusters. We aim to improve the selection of candidate clusters rich
in massive stars with a multiwavelength analysis of photometric
Galactic data that range from optical to mid-infrared wavelengths. We
present a photometric and spectroscopic analysis of five candidate
stellar clusters, which were selected as overdensities with bright
stars (Ks<7mag) in GLIMPSE and 2MASS images. A total of 48 infrared
spectra were obtained. The combination of photometry and spectroscopy
yielded six new red supergiant stars with masses from 10M☉ to
15M☉. Two red supergiants are located at Galactic coordinates
(l,b)=(16.7°, -0.63°) and at a distance of about ∼3.9kpc; four
other red supergiants are members of a cluster at Galactic coordinates
(l,b)=(49.3°, +0.72°) and at a distance of ∼7.0kpc.
Spectroscopic analysis of the brightest stars of detected
overdensities and studies of interstellar extinction along their line
of sights are fundamental to distinguish regions of low extinction
from actual stellar clusters. The census of young star clusters
containing red supergiants is incomplete; in the existing all-sky
near-infrared surveys, they can be identified as overdensities of
bright stars with infrared color-magnitude diagrams characterized by
gaps.
Description:
A set of spectroscopic data was taken with the UKIRT 1-5-micron
Imager Spectrometer (UIST) on Mauna Kea under program ID H243NS (PI:
Kudritzki) on 2008 July 24.
For four of the targeted candidate clusters, additional low-resolution
and medium-resolution spectra were obtained with the SofI spectrograph
mounted on the NTT telescope. Data were taken under program
60.A-9700(E) at Paranal-La Silla Observatory on 2010 August 3, and
under program 089.D-0876 on 2012 June 1.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 146 48 Infrared counterparts of the spectroscopically
observed targets
table4.dat 93 48 List of stars spectroscopically observed with
UKIRT/UIST and NTT/SofI
table6.dat 111 48 Photometric properties of the targeted stars
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/48] Sequential number
3 A1 --- n_Seq [c] JHK magnitudes from UKIDSS (1)
4- 5 I2 h RAh Right ascension (J2000)
7- 8 I2 min RAm Right ascension (J2000)
10- 14 F5.2 s RAs Right ascension (J2000)
16 A1 --- DE- Declination sign (J2000)
17- 18 I2 deg DEd Declination (J2000)
20- 21 I2 arcmin DEm Declination (J2000)
23- 27 F5.2 arcsec DEs Declination (J2000)
29- 33 F5.2 mag J2mag ?=- 2MASS J magnitude (1)
35- 39 F5.2 mag H2mag ?=- 2MASS H magnitude (1)
41- 45 F5.2 mag Ks2mag ?=- 2MASS Ks magnitude (1)
47- 51 F5.2 mag Imag ?=- Denis I magnitude
53- 57 F5.2 mag Jmag ?=- Denis J magnitude
59- 63 F5.2 mag Kdmag ?=- Denis Ks magnitude
65- 69 F5.2 mag [3.6] ?=- Glimpse 3.6um magnitude
71- 75 F5.2 mag [4.5] ?=- Glimpse 4.5um magnitude
77- 81 F5.2 mag [5.8] ?=- Glimpse 4.5um magnitude
83- 87 F5.2 mag [8.0] ?=- Glimpse 8.0um magnitude
89- 92 F4.2 mag Amag ?=- MSX A (8.28um) magnitude (2)
94- 97 F4.2 mag Cmag ?=- MSX C (12.13um) magnitude (2)
99-102 F4.2 mag Dmag ?=- MSX D (14.65um) magnitude (2)
104-107 F4.2 mag Emag ?=- MSX E (21.34um) magnitude (2)
109-112 F4.2 mag W1mag ?=- Wise W1 magnitude (3)
114-117 F4.2 mag W2mag ?=- Wise W2 magnitude (3)
119-123 F5.2 mag W3mag ?=- Wise W3 magnitude (3)
125-128 F4.2 mag W4mag ?=- Wise W4 magnitude (3)
130-134 F5.2 mag Bmag ?=- Nomad B magnitude
136-140 F5.2 mag Vmag ?=- Nomad V magnitude
142-146 F5.2 mag Rmag ?=- Nomad R magnitude
--------------------------------------------------------------------------------
Note (1): for star 41, marked with an *, the adopted J, H, and K measurements
are from the UKIDSS survey.
Note (2): Upper-limit magnitudes were removed.
Note (3): Measurements with signal-to-noise ratio smaller than 2 were removed.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/48] Sequential number
4- 8 F5.2 --- Q1mag ?=- Q1 index (Q1=(J-H)-1.8x(H-Ks))
10- 13 F4.2 --- e_Q1mag ?=- rms uncertainty on Q1
15- 19 F5.2 --- Q2mag ?=- Q2 index (Q2=(J-Ks)-2.69x(Ks-[0.8])
21- 24 F4.2 --- e_Q2mag ?=- rms uncertainty on Q2
26 I1 --- var [0/1] Variable flag (1 for variable)
28- 29 I2 0.1nm EWCO1 ?=- UIST CO equivalent width (2.285-2.315µm)
31- 32 I2 0.1nm EWCO2 ?=- SofIl CO equivalent width (4)
34- 35 I2 0.1nm EWCO3 ?=- SofIm CO equivalent width (2.285-2.307µm)
37- 40 A4 --- Spc1 UIST spectral type by assuming a supergiant
42- 45 A4 --- Spc2 SofIl spectral type by assuming a supergiant
47- 50 A4 --- Spc3 SofIm spectral type by assuming a supergiant
52- 55 A4 --- Spg1 UIST spectral type by assuming a giant class
57- 60 A4 --- Spg2 SofIl spectral type by assuming a giant class
62- 65 A4 --- Spg3 SofIm spectral type by assuming a giant class
67- 68 I2 % H2O [-4/39]?=- H2O index (2.0525-2.0825µm)
70- 80 A11 --- n_H2O Comment on H2O (Mira or AGB)
82- 93 A12 --- Inst Instrument and mode (5)
--------------------------------------------------------------------------------
Note (4): EW(CO)s [2.285-2.315µm] from low-resolution SofI spectra
were multiplied by a factor 1.4.
Note (5): Instrument and mode are:
UIST = UKIRT/UIST (UKIRT 1-5-µm Imager Spectrometer)
SofIl = low-resolution mode of NTT/SofI
SofIm = medium-resolution mode of NTT/SofI
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/48] Sequential number
4- 7 F4.2 arcmin Rad Distance to center of the stellar overdensity
9- 14 A6 --- Field Field designation
16- 20 F5.2 mag Ksmag Ks magnitude
22- 31 A10 --- SpType Spectral type (6)
33- 37 F5.2 mag (J-Ks)0 Deredenned J-Ks colour index
39- 42 F4.2 mag AKsJKs ?=- Extinction in Ks band from J-Ks colour index
44- 47 F4.2 mag AKsHKs Extinction in Ks band from H-Ks colour index
49- 52 F4.2 mag AKsIJ ?=- Extinction in Ks band from I-Js colour index
54- 59 F6.2 mag KsMAG ?=- Absolute Ks magnitude
61- 64 F4.2 mag e_KsMAG ?=- rms uncertainty on KsMAG
66- 70 F5.2 mag MOD [5.9/14.6] Distance modulus
72- 75 F4.2 mag e_MOD [0.1/1.4] rms uncertainty on MOD
77- 81 F5.2 mag BCKs ?=- Bolometric correction in Ks band
83- 86 F4.2 mag e_BCKs ? rms uncertainty on BCKs
88- 92 F5.2 mag Mbol1 [-8/0]?=- Absolute bolometric magnitude
obtained via BCKs
94- 97 F4.2 mag e_Mbol1 ?=- rms uncertainty on Mbol1
99-103 F5.2 mag Mbol2 [-8/-1]?=- Absolute bolometric magnitude
obtained via direct integration
105-108 F4.2 mag e_Mbol2 ?=- rms uncertainty on Mbol2
110-111 A2 --- Notes Notes (7)
--------------------------------------------------------------------------------
Note (6): The M suffix indicates a Mira-like star.
Note (7): The "FG" comment indicates that this star has an AKs at least three
times smaller than the average of the targets in the field. Its distance was
estimated with Drimmel model (a significant number of clump stars were not
available at this AKs). The quoted MOD error (0.8mag) was estimated from
Fig. 6.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Jan-2015