J/ApJ/921/110 NIR sp. of Class 0 protostars in Perseus and Orion (Laos+, 2021)
The near-stellar environment of Class 0 protostars: a first look with
near-infrared spectroscopy.
Laos S., Greene T.P., Najita J.R., Stassun K.G.
<Astrophys. J., 921, 110 (2021)>
=2021ApJ...921..110L 2021ApJ...921..110L
ADC_Keywords: YSOs; Spectra, infrared; Star Forming Region; Molecular clouds
Keywords: Protostars ; Stellar accretion disks ; Near infrared astronomy
Abstract:
We present near-infrared K-band spectra for a sample of seven Class 0
protostars in the Perseus and Orion star-forming regions. We detect
Brγ, CO overtone, and H2 emission, features that probe the
near-circumstellar environment of the protostar and reveal evidence of
magnetospheric accretion, a hot inner disk atmosphere, and outflows,
respectively. Comparing the properties of these features with those of
Class I sources from the literature, we find that their Brγ
emission and CO emission are generally consistent in strength and
velocity width. The Brγ line profiles are broad and centrally
peaked, with FWHMs of ∼200km/s and wings extending to ∼300km/s. The
line ratios of our H2 emission features, which are spatially
extended for some sources, are consistent with shock excitation and
indicate the presence of strong jets or a disk wind. Within our small
sample, the frequency of CO band emission (∼67%) is high relative to
that of Class I samples (∼15%), indicating that Class 0 sources have
high inner disk accretion rates, similar to those of the most actively
accreting Class I sources. Collectively, our results suggest that
Class 0 sources have similar accretion mechanisms to the more evolved
classes, with strong organized stellar magnetic fields established at
the earliest observable stage of evolution.
Description:
We obtained moderate-resolution and moderate-S/N NIR K-band spectra of
our Class 0 protostars on 2019 October 12, 13, and 14 UT with mostly
clear skies and 0.6"-0.7" seeing. All observations were made with the
Keck I telescope on Maunakea, Hawaii, using the MOSFIRE facility
spectrograph in its long-slit mode.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 83 9 *Journal of observations
sp/* . 6 The MOSFIRE K-band spectra (in ASCII format) of
5 Class 0 protostars (Data behind Figure 1) and
the spectrum of HOPS 44 taken on UT Oct 13
(Data behind Figure 11)
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Note on table1.dat: We exclude the spectrum of HOPS 44 from the analysis,
because of its low S/N; see Appendix B. We also do not detect the
continuum of Per-emb 21 (see Section 3).
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
J/A+A/356/1010 : Ortho:para-H2 ratio in C and J shocks (Wilgenbus+, 2000)
J/A+A/365/90 : NIR H lines in TTS (Folha+, 2001)
J/AJ/130/1145 : YSO near-infrared properties (Doppmann+, 2005)
J/ApJ/638/293 : 1.1mm sources in the Perseus Molecular Cloud (Enoch+, 2006)
J/ApJ/646/1009 : Structures of dust in Perseus molecular cloud (Kirk+, 2006)
J/MNRAS/387/954 : H2 imaging of NGC 1333, L1455, L1448 and B1 (Davis+, 2008)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/AJ/140/1214 : NIR spectroscopic survey of class I YSOs (Connelley+, 2010)
J/AJ/144/31 : Spitzer+2MASS phot. of protostar cand. (Kryukova+, 2012)
J/AJ/144/192 : Spitzer survey of Orion A & B. I. YSOs (Megeath+, 2012)
J/ApJ/767/36 : APEX observations of HOPS protostars (Stutz+, 2013)
J/ApJS/220/11 : SEDs of Spitzer YSOs in the Gould Belt (Dunham+, 2015)
J/AJ/150/17 : A catalog of point sources toward NGC 1333 (Rebull, 2015)
J/ApJS/224/5 : The Herschel Orion Protostar Survey: SEDs (Furlan+, 2016)
J/ApJS/224/40 : Catalog of Chandra ACIS point like sources (Wang+, 2016)
J/MNRAS/465/3039 : Eruptive variable protostars from VVV EW (Contreras+, 2017)
J/ApJS/229/28 : SFiNCs: X-ray, IR and membership catalogs (Getman+, 2017)
J/ApJ/834/142 : Gould's Belt Distances Survey. II. OMC (Kounkel+, 2017)
J/ApJ/865/73 : GOBELINS. V. Kinematics of Perseus (Ortiz-Leon+, 2018)
J/ApJS/238/19 : VANDAM IV. Free-free emission (Tychoniec+, 2018)
J/ApJ/890/130 : VANDAM survey of Orion protostars. II. (Tobin+, 2020)
J/A+A/633/A51 : Distances to molecular clouds in SFR (Zucker+, 2020)
J/A+A/650/A43 : Sp. of NGC 1333 Class I-Class II stars (Fiorellino+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Object name
12- 14 A3 --- Reg Region
16- 17 I2 h RAh NIR hour of right ascension (J2000)
19- 20 I2 min RAm NIR minute of right ascension (J2000)
22- 25 F4.1 s RAs NIR second of right ascension (J2000)
27 A1 --- DE- NIR sign of declination (J2000)
28- 29 I2 deg DEd NIR degree of declination (J2000)
31- 32 I2 arcmin DEm NIR arcminute of declination (J2000)
34- 37 F4.1 arcsec DEs NIR arcsecond of declination (J2000)
39- 49 A11 "Y/M/D" Date Date of observation (UT)
51- 52 I2 min Exp [12/34] Integration time
54- 56 F3.1 arcsec Ext [0.7/3.4]? Spatial extent (1)
58- 61 F4.1 km/s Vsys [5.4/11]? Systemic velocity (2)
63- 83 A21 --- File Name of the ASCII file in subdirectory "sp";
column added by CDS
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Note (1): These extents serve as our extractions widths, corresponding to the
spatial width of the individual protostellar continuua observed in our
2D spectral images. The low S/Ns of our Per-emb 21 and HOPS 44
observations precluded the measurement of their spatial extents.
Note (2): System velocities used to shift our continuum-detected Class 0
spectra (Figure 1) into their corresponding systemic rest frames
(Section 3.2). For our Perseus sources, we use the derived velocities
from the C18O (2-1) line fitting in Stephens+ (2019ApJS..245...21S 2019ApJS..245...21S).
For HOPS 32, we average similarly derived velocity values for other
HOPS protostars in Nagy+ (2020A&A...642A.137N 2020A&A...642A.137N) as a rough proxy.
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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- 18 F18.16 um lambda [2/2.4] Wavelength
20- 41 E22.18 mW/m2/um S [-4.4e-14/1.7e-11] Flux density
in erg/cm2/s/µm units
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Feb-2023