Kinematics of a Young Low-mass Star-forming Core: Understanding the Evolutionary State of the First-core Candidate L1451-mm

Journal Article · Mon Mar 20 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/838/1/60· OSTI ID:22661242

Maureira, María José; Arce, Héctor G. ^[1]; Dunham, Michael M. ^[2]; Pineda, Jaime E. ^[3]; Fernández-López, Manuel ^[4]; Chen, Xuepeng ^[5]; Mardones, Diego ^[6]

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1. Astronomy Department, Yale University, New Haven, CT 06511 (United States)
2. Department of Physics, State University of New York at Fredonia, Fredonia, NY 14063 (United States)
3. Max-Planck Institute for Extraterrestrial Physics, Giessenbachstrasse 1, D-85748 Garching (Germany)
4. Instituto Argentino de Radioastronomía, CCT-La Plata (CONICET), C.C.5, 1894, Villa Elisa (Argentina)
5. Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008 (China)
6. Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile)

We use 3 mm multiline and continuum CARMA observations toward the first hydrostatic core (FHSC) candidate L1451-mm to characterize the envelope kinematics at 1000 au scales and investigate its evolutionary state. We detect evidence of infall and rotation in the NH{sub 2}D(1{sub 1,1}–1{sub 0,1}), N{sub 2}H{sup +}(1–0), and HCN(1–0) molecular lines. We compare the position–velocity diagram of the NH{sub 2}D(1{sub 1,1}–1{sub 0,1}) line with a simple kinematic model and find that it is consistent with an envelope that is both infalling and rotating while conserving angular momentum around a central mass of about 0.06 M {sub ⊙}. The N{sub 2}H{sup +}(1–0) LTE mass of the envelope along with the inferred infall velocity leads to a mass infall rate of approximately 6 × 10{sup −6} M {sub ⊙} yr{sup −1}, implying a young age of 10{sup 4} years for this FHSC candidate. Assuming that the accretion onto the central object is the same as the infall rate, we obtain a minimum source size of 1.5–5 au, consistent with the size expected for a first core. We do not see any evidence of outflow motions or signs of outflow–envelope interaction at scales ≳2000 au. This is consistent with previous observations that revealed a very compact outflow (≲500 au). We conclude that L1451-mm is indeed at a very early stage of evolution, either a first core or an extremely young Class 0 protostar. Our results provide strong evidence that L1451-mm is the best candidate for being a bona fide first core.

• OSTI ID: 22661242
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 838; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANGULAR MOMENTUM
APPROXIMATIONS
COMPARATIVE EVALUATIONS
EVOLUTION
HYDROSTATICS
INTERACTIONS
MASS
PROTOSTARS
ROTATION
STARS
VELOCITY