The Near Stellar Environment of Class 0 Protostars: A First Look with Near-Infrared Spectroscopy

Abstract

We present near-infrared K-band spectra for a sample of 7 Class 0 protostars in the Perseus and Orion star-forming regions. We detect Br gamma, 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 Br gamma and CO emission are generally consistent in strength and velocity width. The Br gamma line profiles are broad and centrally peaked, with FWHMs of 200 km/s and wings extending to 300 km/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 0s 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.

24 pages, 11 figures, accepted for publication in the Astrophysical Journal

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Cited by in corpus (10)

• The Mass Accretion Rate and Stellar Properties in Class I Protostars
• Diagnosing FUor-like Sources: The Parameter Space of Viscously Heated Disks in the Optical and Near-IR
• Dissecting the different components of the modest accretion bursts of the very young protostar HOPS 373
• The relation between the Mass Accretion Rate and the Disk Mass in Class I Protostars
• Formation of low mass protostars and their circumstellar disks
• Massive pre-main-sequence stars in M17: $1^{\mathrm{st}}$ and $2^{\mathrm{nd}}$ overtone CO bandhead emission and the thermal infrared
• Birth of magnetized low-mass protostars and circumstellar disks
• The NEMESIS Catalogue of Young Stellar Objects for the Orion Star Formation Complex. I. General description of data curation
• What governs the spin distribution of very young < 1 Myr low mass stars
• Magnetic field measurements in a sample of Class I and flat-spectrum protostars observed with SPIRou