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J/A+A/604/A78   M17 massive pms stars X-shooter spectra  (Ramirez-Tannus+, 2017)

Massive pre-main-sequence stars in M17. Ramirez-Tannus M.C., Kaper L., de Koter A., Tramper F., Bik A., Ellerbroek L.E., Ochsendorf B.B., Ramirez-Agudelo O.H., Sana H. <Astron. Astrophys. 604, A78 (2017)> =2017A&A...604A..78R (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; Stars, pre-main sequence ; YSOs ; Stars, OB ; Spectroscopy Keywords: stars: pre-main-sequence - stars: massive - stars: early-type - HII regions - stars: variables: T Tauri, Herbig Ae/Be - accretion, accretion disks Abstract: The formation process of massive stars is still poorly understood. Massive young stellar objects (mYSOs) are deeply embedded in their parental clouds; these objects are rare, and thus typically distant, and their reddened spectra usually preclude the determination of their photospheric parameters. M17 is one of the best-studied HII regions in the sky, is relatively nearby, and hosts a young stellar population. We have obtained optical to near-infrared spectra of previously identified candidate mYSOs and a few OB stars in this region with X-shooter on the ESO Very Large Telescope. The large wavelength coverage enables a detailed spectroscopic analysis of the photospheres and circumstellar disks of these candidate mYSOs. We confirm the pre-main-sequence (PMS) nature of six of the stars and characterise the O stars. The PMS stars have radii that are consistent with being contracting towards the main sequence and are surrounded by a remnant accretion disk. The observed infrared excess and the double-peaked emission lines provide an opportunity to measure structured velocity profiles in the disks. We compare the observed properties of this unique sample of young massive stars with evolutionary tracks of massive protostars and propose that these mYSOs near the western edge of the HII region are on their way to become main-sequence stars (∼6-20M) after having undergone high mass accretion rates (dMacc/dt∼10-4-10-3M/yr) Their spin distribution upon arrival at the zero age main-sequence (ZAMS) is consistent with that observed for young B stars, assuming conservation of angular momentum and homologous contraction. Description: Normalized X-shooter spectra of the PMS and OB stars in M17 studied. The X-shooter spectra were obtained under good weather conditions with seeing ranging from 0.5" and 1" and clear sky. With the exception of the 2012 B289 spectrum and the 2009 B275 science verification spectrum, the spectrograph slit widths used were 1" (UVB, 300-590nm), 0.9" (VIS, 550-1020nm), and 0.4" (NIR, 1000-2480nm), resulting in a spectral resolving power of 5100, 8800, and 11300, respectively. The slit widths for the 2010 B275 observations were 1.6", 0.9", and 0.9" resulting in a resolving power of 3300, 8800, and 5600, respectively. For the 2012 B289 observations we used the 0.8", 0.7", and 0.4" slits corresponding to a resolving power of 6200, 11000, and 11300 for the UVB, VIS, and NIR arms, respectively. The spectra were taken in nodding mode and reduced using the X-shooter pipeline version 2.7.1 running under the ESO Reflex environment version 2.8.4. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 100 17 Journal of X-shooter observations sp/* 51 16 Individual normalised spectra of the studied stars in M17
See also: II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) II/336 : AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016) J/ApJS/169/353 : Chandra sources in M17 (Broos+, 2007) J/ApJ/714/L285 : YSO candidates in M17 SWex (Povich+, 2010) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Name Object name (BNNN) as in Master's thesis of Bumgardner (1992, thesis, Ohio State Univ., Columbus), Cl* NGC 6618 B NNN in Simbad 5 A1 --- n_Name [*] Note on Name (1) 6- 10 A5 --- OName Other name 12- 13 I2 --- CEN ?=- Chini et al. (1980A&A....91..186C) identification number, Cl* NGC 6618 CEN NNN in Simbad 15- 17 I3 --- OI ? Ogura & Ishida (1976PASJ...28...35O) identification number, NGC 6618 NNN in Simbad 19- 20 I2 h RAh Right ascension (J2000) 22- 23 I2 min RAm Right ascension (J2000) 25- 29 F5.2 s RAs Right ascension (J2000) 31 A1 --- DE- Declination sign (J2000) 32- 33 I2 deg DEd Declination (J2000) 35- 36 I2 arcmin DEm Declination (J2000) 38- 42 F5.2 arcsec DEs Declination (J2000) 44- 49 F6.3 mag Vmag ? V magnitude 50 A1 --- r_Vmag [abc] Reference for Vmag (2) 52- 57 F6.3 mag Kmag 2MASS K magnitude (Cutri et al., 2003, Cat. II/246) 59- 68 A10 "date" Obs.Date Observation date 70- 74 A5 --- ExpTUVB UVB arm exposure times (s) 76- 80 A5 --- ExpTVIS VIS arm exposure times (s) 82- 87 A6 --- ExpTNIR NIR arm exposure times (s) 89-100 A12 --- FileName Name of the file with spectrum, in subdirectory sp
Note (1): B111, B163, B164, and B253 are associated with NGC 6618 (Povich et al., 2009, Cat. J/ApJ/696/1278). Note (2): References as follows: a = AAVSO Photometric all sky survey (APASS) catalog: https://www.aavso.org/apass , Cat. II/336 b = Chini et al. (1980A&A....91..186C) c = Hoffmeister et al. (2008ApJ...686..310H)
Byte-by-byte Description of file: sp/*
Bytes Format Units Label Explanations
1- 24 E24.18 nm lambda Wavelength 26- 51 E26.18 --- NFlux ?=- Normalised flux
Acknowledgements: Maria Claudia Ramirez-Tannus, m.c.ramireztannus(at)uva.nl
(End) Maria Claudia Ramirez-Tannus [UVA], Patricia Vannier [CDS] 10-May-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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