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J/AJ/154/102  LMC blue supergiants spectroscopic observations  (Urbaneja+, 2017)

LMC blue supergiant stars and the calibration of the Flux-weighted Gravity-Luminosity Relationship. Urbaneja M.A., Kudritzki R.-P., Gieren W., Pietrzynski G., Bresolin F., Przybilla N. <Astron. J., 154, 102-102 (2017)> =2017AJ....154..102U (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Stars, supergiant ; Stars, blue ; Spectral types ; Effective temperatures ; Abundances ; Photometry, UBV ; Photometry, infrared Keywords: galaxies: distances and redshifts - galaxies: individual (LMC) - stars: early-type - supergiants Abstract: High-quality spectra of 90 blue supergiant stars in the Large Magellanic Cloud are analyzed with respect to effective temperature, gravity, metallicity, reddening, extinction, and extinction law. An average metallicity, based on Fe and Mg abundances, relative to the Sun of [Z]=-0.35±0.09 dex is obtained. The reddening distribution peaks at E(B-V)=0.08 mag, but significantly larger values are also encountered. A wide distribution of the ratio of extinction to reddening is found ranging from RV=2 to 6. The results are used to investigate the blue supergiant relationship between flux-weighted gravity, gF=g/Teff4, and absolute bolometric magnitude Mbol. The existence of a tight relationship, the Flux-weighted Gravity-Luminosity Relationship (FGLR), is confirmed. However, in contrast to previous work, the observations reveal that the FGLR is divided into two parts with a different slope. For flux-weighted gravities larger than 1.30 dex, the slope is similar to that found in previous work, but the relationship becomes significantly steeper for smaller values of the flux-weighted gravity. A new calibration of the FGLR for extragalactic distance determinations is provided. Description: We present new spectroscopic observations of a sample of 32 blue supergiants obtained with the Magellan Echellete spectrograph. Our core sample is complemented with spectra of another 58 LMC supergiant stars collected from other sources. Optical spectra of 32 LMC blue supergiant stars were collected during the nights of 2008 October 29th and 30th, and 2010 November 10th, using the Magellan Echellete spectrograph (MagE, Marshall et al. 2008SPIE.7014E..54M), a medium-resolution, cross-dispersed, optical spectrograph on the Clay Telescope at Las Campanas Observatory. We selected the 1 arcsec slit, providing a nominal resolving power of R∼4100. MagE has a plate scale of 0.3 arsec/pixel, and it covers a wide spectral range, ∼3100-10000 Å. Objects: --------------------------------------------------------------- RA (ICRS) DE Designation(s) --------------------------------------------------------------- 05 23 34.6 -69 45 22 LMC = NAME Large Magellanic Cloud --------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table11.dat 80 90 LMC Supergiants - Optical Photometry table12.dat 70 87 LMC Supergiants - 2MASS Photometry (Skrutskie et al. 2006, Cat. VII/233) table13.dat 83 87 LMC Supergiants - IRAC Photometry (Meixner et al. 2006, J/AJ/132/2268) table1.dat 67 23 LMC BA Supergiants Observed with MagE table2.dat 67 23 LMC OB Supergiants (MagE and FLAMES I) table3.dat 67 29 LMC OB Supergiants (FEROS) table4.dat 67 15 LMC VFTS OB Supergiants table6.dat 138 23 LMC BA Supergiants Results table7.dat 138 23 LMC OB Supergiants Results (MagE and FLAMES I) table8.dat 138 29 LMC OB Supergiants Results (FEROS) table9.dat 138 15 LMC VFTS OB Supergiants Results table10.dat 63 17 BA Supergiants Results Based on the Balmer Jump as Teff Indicator, at Nominal and Degraded Spectral Resolution
See also: VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006) J/A+AS/24/35 : LMC A-F supergiants (Stock+, 1976) J/A+AS/35/347 : OB and Supergiants stars in LMC (Philip+, 1979) J/AN/320/105 : Spectrophotometry of 26 supergiants in the LMC (Oestreicher+ 1999) J/A+A/456/623 : VLT-FLAMES survey of massive stars (Evans+, 2006) J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006) J/A+A/575/A70 : VLT-FLAMES Tarantula Survey: B supergiants (McEvoy+, 2015) Byte-by-byte Description of file: table11.dat
Bytes Format Units Label Explanations
1- 11 A11 --- Star Star name 13- 17 F5.2 mag Vmag [9.87/15.53] Johnson V band magnitude (1) 19- 23 F5.2 mag B-V [-0.2/0.5] Johnson B-V color index (1) 25- 29 F5.2 mag U-B [-0.98/0.2]? Johnson U-B color index (1) 31- 60 A30 --- Ref Reference 62- 80 A19 --- BibCode BibCode of the reference
Note (1): Unfortunately, individual errors in the photometric measurements for the full sample are not readily available. Many of the works do not provide this valuable information. In what follows, we list the uncertainties quoted in those references listed: (a) Ardeberg et al. (1972A&AS....6..249A): sig(V)=0.017, sig(B-V)=0.013, sig(U-B)=0.017; (b) Isserstedt (1975A&AS...19..259I, 1979A&AS...38..239I, 1982A&AS...50....7I): sig(V)=0.025, sig(B-V)=0.020, sig(U-B)= 0.025; (c) Nicolet (1978A&AS...34....1N): sig(V)=0.02, sig(B-V)=0.015, sig(U-B)=0.02; (d) Gordon et al. (2003ApJ...594..279G) - for Sk-68 26: sig(V)=0.003, sig(B-V)=0.002, sig(U-B)=0.001. In lieu of this information being missing for all other references, we adopted a flat error of sig(B-V)=0.02 mag and sig(V)=0.02 mag for all of the optical photometry used in this work.
Byte-by-byte Description of file: table12.dat
Bytes Format Units Label Explanations
1- 11 A11 --- Star Star name 13- 31 A19 --- ID SSTISAGEMC identifier (JHHMMSS.ss+DDMMSS.s) 33- 38 F6.3 mag Jmag [9.604/14.698]? 2MASS J band magnitude 40- 44 F5.3 mag e_Jmag [0.02/0.038]? Uncertainty in Jmag 46- 51 F6.3 mag Hmag [9.54/14.715]? 2MASS H band magnitude 53- 57 F5.3 mag e_Hmag [0.01/0.05]? Uncertainty in Hmag 59- 64 F6.3 mag Ksmag [9.474/14.686]? 2MASS KS band magnitude 66- 70 F5.3 mag e_Ksmag [0.019/0.063]? Uncertainty in Ksmag
Byte-by-byte Description of file: table13.dat
Bytes Format Units Label Explanations
1- 11 A11 --- Star Star name 13- 31 A19 --- ID SSTISAGEMC identifier (JHHMMSS.ss+DDMMSS.s) 33- 38 F6.3 mag 3.6mag [9.272/14.655]? Spitzer/IRAC 3.6µm band magnitude 40- 44 F5.3 mag e_3.6mag [0.019/0.069]? Uncertainty in 3.6mag 46- 51 F6.3 mag 4.5mag [9.246/14.646]? Spitzer/IRAC 4.5µm band magnitude 53- 57 F5.3 mag e_4.5mag [0.017/0.071]? Uncertainty in 4.5mag 59- 64 F6.3 mag 5.8mag [9.197/14.601]? Spitzer/IRAC 5.8µm band magnitude 66- 70 F5.3 mag e_5.8mag [0.02/0.163]? Uncertainty in 5.8mag 72- 77 F6.3 mag 8.0mag [9.152/12.996]? Spitzer/IRAC 8.0µm band magnitude 79- 83 F5.3 mag e_8.0mag [0.022/0.127]? Uncertainty in 8.0mag
Byte-by-byte Description of file: table[1234].dat
Bytes Format Units Label Explanations
1- 11 A11 --- Star Star name 13- 14 I2 h RAh Hour of Right Ascension (J2000) 16- 17 I2 min RAm Minute of Right Ascension (J2000) 19- 26 F8.5 s RAs Second of Right Ascension (J2000) 28 A1 --- DE- Sign of the Declination (J2000) 29- 30 I2 deg DEd Degree of Declination (J2000) 32- 33 I2 arcmin DEm Arcminute of Declination (J2000) 35- 41 F7.4 arcsec DEs Arcsecond of Declination (J2000) 43- 47 F5.2 mag Vmag [9.87/15.53] V band magnitude 49- 63 A15 --- SpType MK spectral type 65- 67 A3 --- r_SpType Reference for SpType (1)
Note (1): Reference as follows: tw = This work; A72 = Ardeberg et al. (1972A+AS....6..249A); E06 = Evans et al. (2006, J/A+A/456/623); F88 = Fitzpatrick (1988ApJ...335..703F); S76 = Stock et al. (1976, J/A+AS/24/35); F91 = Fitzpatrick (1991PASP..103.1123F); W02 = Walborn et al. (2002ApJS..141..443W); F87 = Fitzpatrick (1987ApJ...312..596F); M95 = Massey et al. (1995ApJ...438..188M); M10 = Massey (2010ASPC..425....3M). Reference for the spectral classification in Table 4: McEvoy et al. (2015, J/A+A/575/A70).
Byte-by-byte Description of file: table[6789].dat
Bytes Format Units Label Explanations
1- 11 A11 --- Star Star name 13- 18 F6.4 10+4K Teff [0.8465/2.7] Effective temperature 20- 25 F6.4 10+4K e_Teff [0.0030/0.0755] Lower limit uncertainty in Teff 27- 32 F6.4 10+4K E_Teff [0.0035/0.081] Upper limit uncertainty in Teff 34- 37 F4.2 [-] loggF [1.10/1.95] Log of flux-weighted gravity (dex) 39- 42 F4.2 [-] e_loggF [0.01/0.09] Lower limit uncertainty in loggF (dex) 44- 47 F4.2 [-] E_loggF [0.01/0.08] Upper limit uncertainty in loggF (dex) 49- 52 F4.2 [-] [Mg/H] [6.92/7.49] Mg abundance (dex) 54- 57 F4.2 [-] e_[Mg/H] [0.04/0.27] Lower limit uncertainty in [Mg/H] (dex) 59- 62 F4.2 [-] E_[Mg/H] [0.04/0.27] Upper limit uncertainty in [Mg/H] (dex) 64- 67 F4.2 [-] [Fe/H] [7.01/7.31]? Fe abundance (dex) (only in Table 6) 69- 72 F4.2 [-] e_[Fe/H] [0.05/0.18]? Lower limit uncertainty in [Fe/H] (dex) (only in Table 6) 74- 77 F4.2 [-] E_[Fe/H] [0.08/0.21]? Upper limit uncertainty in [Fe/H] (dex) (only in Table 6) 79- 83 F5.2 mag BC [-2.66/-0.01] Bolometric correction 85- 88 F4.2 mag e_BC [0.01/0.06] Uncertainty in BC 90- 93 F4.2 mag E(B-V) [0.03/0.64] Reddening 95- 98 F4.2 mag e_E(B-V) [0.01/0.04] Lower limit uncertainty in E(B-V) 100-103 F4.2 mag E_E(B-V) [0.01/0.04] Upper limit uncertainty in E(B-V) 105-108 F4.2 --- RV [1.27/8.52] Ratio of visual extinction to reddening RV=AV/E(B-V) 110-113 F4.2 --- e_RV [0.21/2.98] Lower limit uncertainty in RV 115-118 F4.2 --- E_RV [0.19/2.37] Upper limit uncertainty in RV 120-123 F4.2 mag AV [0.13/2.31] Visual extinction 125-128 F4.2 mag e_AV [0.03/0.06] Lower limit uncertainty in AV 130-133 F4.2 mag E_AV [0.03/0.06] Upper limit uncertainty in AV 135-138 F4.2 --- chi2 [0.06/3.04] Final reduced-χ2 value resulting from the RV-E(B-V) analysis
Byte-by-byte Description of file: table10.dat
Bytes Format Units Label Explanations
1- 10 A10 --- Star Star name 12- 15 F4.2 --- DB [0.16/0.62] Balmer jump DB index (dex) (1) 17- 22 F6.4 10+4K Teff1 [0.834/1.23] Effective temperature derived at nominal spectral resolution 24- 29 F6.4 10+4K e_Teff1 [0.0045/0.0375] Uncertainty in Teff1 31- 34 F4.2 [-] loggF1 [1.24/1.91] Log of flux-weighted gravity derived at nominal spectral resolution (dex) 36- 39 F4.2 [-] e_loggF1 [0.03/0.07] Uncertainty in loggF1 (dex) 41- 46 F6.4 10+4K Teff2 [0.8535/1.2375] Effective temperature derived at degraded spectral resolution 48- 53 F6.4 10+4K e_Teff2 [0.0103/0.0301] Uncertainty in Teff2 55- 58 F4.2 [-] loggF2 [1.24/1.9] Log of flux-weighted gravity derived at degraded spectral resolution (dex) 60- 63 F4.2 [-] e_loggF2 [0.01/0.09] Uncertainty in loggF2 (dex)
Note (1): The uncertainty in the measured DB index at the nominal resolution is in all cases smaller than 0.01 dex. See text for details.
History: From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 19-Jul-2018
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