Spectroscopic Evidence for Gas Infall in GF9-2

Abstract

We present spectroscopic evidence for infall motion of gas in the natal cloud core harboring an extremely young low-mass protostar GF9-2. We previously discussed that the ongoing collapse of the GF9-2 core has agreement with the Larson-Penston-Hunter (LPH) theoretical solution for the gravitational collapse of a core (Furuya et al.; paper I). To discuss the gas infall on firmer ground, we have carried out On-The-Fly mapping observations of the HCO+ (1--0) line using the Nobeyama 45m telescope equipped with the 25 Beam Array Receiver System. Furthermore, we observed the HCN (1--0) line with the 45m telescope, and the HCO+ (3--2) line with the Caltech Submillimeter Observatory 10.4 m telescope. The optically thick HCO+ and HCN lines show blueskewed profiles whose deepest absorptions are seen at the peak velocity of optically thin lines, i.e., the systemic velocity of the cloud (paper I), indicating the presence of gas infall toward the central protostar. We compared the observed HCO+ line profiles with model ones by solving the radiative transfer in the core under LTE assumption.We found that the core gas has a constant infall velocity of ~0.5 km/s in the central region, leading to a mass accretion rate of 2.5x10^{-5} Msun/yr. Consequently, we confirm that the gas infall in the GF9-2 core is consistent with the LPH solution.

13 pages, 5 figure, full resolution version of the figures are available at http://subarutelescope.org/staff/rsf/publication.html

References in corpus (8)

• Theory of Star Formation
• A Search for Infall Motions Toward Nearby Young Stellar Objects
• Molecular Evolution in Collapsing Prestellar Cores
• On-The-Fly Observing System of the Nobeyama 45-m and ASTE 10-m Telescopes
• Envelope Emission in Young Stellar Systems: A Sub-Arcsecond Survey of Circumstellar Structure
• IRAS 16293-2422: Evidence for Infall onto a Counter-Rotating Protostellar Accretion Disk
• The Initial Conditions for Gravitational Collapse of a Core: An Extremely Young Low-Mass Class 0 Protostar GF9-2
• Low-Mass Star Forming Cores in the GF9 Filament

Cited by in corpus (4)

• Warm Extended Dense Gas Lurking At The Heart Of A Cold Collapsing Dense Core
• A Dynamically Collapsing Core and a Precursor of a Core in a Filament Supported by Turbulent and Magnetic Pressures
• Magnetic Field Uniformity Across the GF 9-2 YSO, L1082C Dense Core, and GF 9 Filamentary Dark Cloud
• A 1000 AU Scale Molecular Outflow Driven by a Protostar with an age of <4000 Years