J/AJ/165/3 SPICY. II. Spectroscopic observations of 26 YSOs (Kuhn+, 2023)
Spectroscopic confirmation of a population of isolated, intermediate-mass young
stellar objects.
Kuhn M.A., Saber R., Povich M.S., de Souza R.S., Krone-Martins A.,
Ishida E.E.O., Zucker C., Benjamin R.A., Hillenbrand L.A.,
Castro-Ginard A., Zhou X., For the COIN collaboration
<Astron. J., 165, 3 (2023)>
=2023AJ....165....3K 2023AJ....165....3K
ADC_Keywords: YSOs; Star Forming Region; Spectra, optical; Spectral types;
Effective temperatures; Stars, masses; Stars, ages;
Stars, diameters; Extinction
Keywords: Herbig Ae/Be stars ; T Tauri stars ; Spectroscopy ; Star formation ;
Young stellar objects
Abstract:
Wide-field searches for young stellar objects (YSOs) can place useful
constraints on the prevalence of clustered versus distributed star
formation. The Spitzer/IRAC Candidate YSO (SPICY) catalog is one of
the largest compilations of such objects (∼120000 candidates in the
Galactic midplane). Many SPICY candidates are spatially clustered,
but, perhaps surprisingly, approximately half the candidates appear
spatially distributed. To better characterize this unexpected
population and confirm its nature, we obtained Palomar/DBSP
spectroscopy for 26 of the optically bright (G<15mag) "isolated" YSO
candidates. We confirm the YSO classifications of all 26 sources based
on their positions on the Hertzsprung-Russell diagram, H and Ca ii
line emission from over half the sample, and robust detection of
infrared excesses. This implies a contamination rate of <10% for SPICY
stars that meet our optical selection criteria. Spectral types range
from B4 to K3, with A-type stars being the most common. Spectral
energy distributions, diffuse interstellar bands, and Galactic
extinction maps indicate moderate-to-high extinction. Stellar masses
range from ∼1 to 7M☉, and the estimated accretion rates, ranging
from 3x10-8 to 3x10-7M☉/yr, are typical for YSOs in this mass
range. The 3D spatial distribution of these stars, based on Gaia
astrometry, reveals that the "isolated" YSOs are not evenly
distributed in the Solar neighborhood but are concentrated in
kiloparsec-scale dusty Galactic structures that also contain the
majority of the SPICY YSO clusters. Thus, the processes that produce
large Galactic star-forming structures may yield nearly as many
distributed as clustered YSOs.
Description:
The stars were observed using the Double Spectrograph (DBSP) on the
200inch Hale Telescope at Palomar Observatory on June 5th, 2021 UT.
The observations were taken using the D68 dichroic, with the
600line/mm grating blazed at 3780Å for the blue side and the
1200line/mm grating blazed at 7100Å for the red side. Observations
were made with the 1" slit. This gave a wavelength range of
3816-6874Å and 7381-9015Å for the two spectrographs, with
resolutions of R∼2000 and R∼6000.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 74 26 Stellar properties
sp/* . 52 Individual spectra in ASCII format
fits/* . 52 Individual spectra in FITS format
(Data behind Figure 3)
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See also:
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/314 : UKIDSS-DR8 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/316 : UKIDSS-DR6 Galactic Plane Survey (Lucas+ 2012)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
II/360 : Gaia DR2 x AllWISE catalogue (Marton+, 2019)
II/364 : VIRAC. The VVV Infrared Astrometric Catalogue (Smith+, 2019)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
J/AJ/127/1632 : UBVR(UIT) photometry of O and OB stars in SMC (Oey+, 2004)
J/other/ARA+A/42.685 : Young stars near the Sun (Zuckerman+, 2004)
J/A+A/492/277 : Analysis of Collinder 69 stars with VOSA (Bayo+, 2008)
J/AJ/136/2413 : Galactic midplane Spitzer red sources (Robitaille+, 2008)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/ApJ/720/679 : Optical spectroscopy in Cygnus X region (Beerer+, 2010)
J/ApJS/186/259 : Taurus Spitzer survey; new candidate members (Rebull+, 2010)
J/ApJS/194/14 : A Pan-Carina YSO catalog (Povich+, 2011)
J/ApJS/209/32 : Probable young stars in the MYStIX project (Broos+, 2013)
J/ApJ/774/72 : Measurements 19 DIBs & other interstellar lines (Kos+, 2013)
J/ApJS/209/29 : MYStIX; Mid-IR observations and catalogs (Kuhn+, 2013)
J/ApJS/208/9 : Intrinsic colors & temperatures of PMS stars (Pecaut+, 2013)
J/ApJS/209/31 : The MYStIX IR-Excess Source catalog (MIRES) (Povich+, 2013)
J/MNRAS/440/2036 : VPHAS+ survey synthetic colours (Drew+, 2014)
J/ApJ/787/107 : Spatial structure young stellar clusters. I. (Kuhn+, 2014)
J/MNRAS/453/976 : Herbig Ae/Be X-shooter observations (Fairlamb+, 2015)
J/AJ/149/64 : MIPSGAL 24µm point source catalog (Gutermuth+, 2015)
J/ApJ/802/60 : Structure of young stellar clusters. II. (Kuhn+, 2015)
J/MNRAS/458/3479 : SVM selection of WISE YSO Candidates (Marton+, 2016)
J/A+A/588/A25 : Post-AGB & CSPN evolutionary models (Miller Bertolami, 2016)
J/ApJS/230/16 : 5 through L3 empirical stellar spectra SDSS (Kesseli+, 2017)
J/AJ/156/241 : 1st catalog variable stars measured by ATLAS (Heinze+, 2018)
J/ApJ/868/43 : AO images of WISE YSO candidates (Silverberg+, 2018)
J/A+A/620/A128 : Gaia DR2 study of Herbig Ae/Be stars (Vioque+, 2018)
J/A+A/620/A172 : Solar neighbourhood young stars 3D mapping (Zari+, 2018)
J/MNRAS/483/5077 : Machine learning to identify symbiotic stars (Akras+, 2019)
J/A+A/626/A80 : Census RhoOph candidate members Gaia DR2 (Canovas+, 2019)
J/A+A/625/A135 : Galactic inters. dust Gaia-2MASS 3D maps (Lallement+, 2019)
J/ApJ/880/9 : Spitzer obs. of YSOs in the SMOG field (Winston+, 2019)
J/A+A/640/A1 : Portrait Galactic disc (Cantat-Gaudin+, 2020)
J/ApJ/904/146 : Young stars in North America & Pelican Nebulae (Fang+, 2020)
J/AJ/160/279 : Untangling Galaxy II. Structure within 3kpc (Kounkel+, 2020)
J/ApJ/899/128 : Validated & members of NGC7000/IC5070 Complex (Kuhn+, 2020)
J/A+A/638/A21 : New Herbig Ae/Be and classical Be stars (Vioque+, 2020)
J/MNRAS/493/234 : Herbig Ae/Be accretion & mechanisms (Wichittanakom+ 2020)
J/A+A/633/A51 : Distances to molecular clouds in SFR (Zucker+, 2020)
J/ApJ/917/23 : SPYGLASS. I. Mapping young stellar structures (Kerr+, 2021)
J/ApJS/254/33 : Gal. midplane Spitzer/IRAC cand YSOs (SPICY) (Kuhn+, 2021)
J/AJ/162/282 : Untangling Galaxy. III. Pre-main-sequence (Mcbride+, 2021)
J/ApJ/930/39 : 128 new Herbig stars (Vioque+, 2022)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- SPICY SPICY star identifier
8- 9 A2 --- SpType Spectral type derived from spectral analysis
11 I1 --- E_SpType [1/4] Positive error on SpType
13 I1 --- e_SpType [0/8] Negative error on SpType
15- 19 I5 K Teff [4550/16700] Effective temperature derived
from spectral analysis
21- 24 I4 K e_Teff [40/2700] Negative error on Teff
26- 29 I4 K E_Teff [60/1800] Positive error on Teff
31- 34 F4.2 mag Av [1.31/5.77] Extinction (1)
36- 39 F4.2 mag e_Av [0.1/0.6] Error on Av
41- 44 F4.2 Lsun Lum [0.07/3.35] log luminosity (1)
46- 49 F4.2 Lsun e_Lum [0.1/0.3] Error on Lum
51- 53 F3.1 Rsun Rad [1.1/8.9] Stellar radius (1)
55- 57 F3.1 Rsun e_Rad [0.2/3] Error on Rad
59- 62 F4.1 Myr Age [0.3/25.7] Stellar age (2)
64- 66 F3.1 Myr e_Age [0.3/8] Error on Age
68- 70 F3.1 Msun Mass [1/6.6] Stellar mass (2)
72- 74 F3.1 Msun e_Mass [0.1/2] Error on Mass
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Note (1): Extinction, luminosity and radius derived from SED fitting.
Note (2): Age and Mass derived from pre-main sequence models.
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 22 E22.14 0.1nm lambda [3735.3/9056] Wavelength (in Å)
24- 45 E22.14 --- Flux [-186959/302638] Normalized flux
47- 68 E22.14 --- e_Flux [0/1.02] Error on Flux
70 I1 --- Mask [0/1] Mask
72- 93 E22.14 --- Telluric [0/1]? Telluric value (only for red band)
95-116 E22.14 --- Model [0/3038]? obj_model value (only for red band)
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History:
From electronic version of the journal
References:
Kuhn et al. Paper I : 2021ApJS..254...33K 2021ApJS..254...33K Cat. J/ApJS/254/33
(End) Prepared by [AAS], Coralie Fix |CDS], 06-Nov-2023