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. =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 Br{gamma}, CO overtone, and H_2_ 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 Br{gamma} emission and CO emission are generally consistent in strength and velocity width. The Br{gamma} line profiles are broad and centrally peaked, with FWHMs of ~200km/s and wings extending to ~300km/s. The line ratios of our H_2_ 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: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- 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) -------------------------------------------------------------------------------- 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). -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- 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 C^18^O (2-1) line fitting in Stephens+ (2019ApJS..245...21S). For HOPS 32, we average similarly derived velocity values for other HOPS protostars in Nagy+ (2020A&A...642A.137N) as a rough proxy. -------------------------------------------------------------------------------- Byte-by-byte Description of file: sp/* -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 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/cm^2^/s/{mu}m units -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Feb-2023