skip to main content

SciTech ConnectSciTech Connect

Title: G11.92–0.61-MM2: A BONAFIDE MASSIVE PRESTELLAR CORE?

Core accretion models of massive star formation require the existence of stable massive starless cores, but robust observational examples of such objects have proven elusive. We report subarcsecond-resolution Submillimeter Array (SMA) 1.3 mm, 1.1 mm, and 0.88 mm and Very Large Array 1.3 cm observations of an excellent massive starless core candidate, G11.92–0.61-MM2, initially identified in the course of studies of GLIMPSE Extended Green Objects (EGOs). Separated by ∼7.''2 from the nearby MM1 protostellar hot core, MM2 is a strong, compact dust continuum source (submillimeter spectral index α = 2.6 ± 0.1), but is devoid of star formation indicators. In contrast to MM1, MM2 has no masers, no centimeter continuum, and no (sub)millimeter wavelength line emission in ∼24 GHz of bandwidth observed with the SMA, including N{sub 2}H{sup +}(3-2), HCO{sup +}(3-2), and HCN(3-2). Additionally, there is no evidence for an outflow driven by MM2. The (sub)millimeter spectral energy distribution of MM2 is best fit with a dust temperature of ∼17-19 K and luminosity of ∼5-7 L {sub ☉}. The combined physical properties of MM2, as inferred from its dust continuum emission, are extreme: M ≳ 30 M {sub ☉} within a radius <1000 AU, N{sub H{sub 2}}>10{sup 25} cm{sup –2}more » and n{sub H{sub 2}} >10{sup 9} cm{sup –3}. Comparison of the molecular abundance limits derived from our SMA observations with gas-grain chemical models indicates that extremely dense (n(H) >> 10{sup 8} cm{sup –3}), cold (<20 K) conditions are required to explain the lack of observed (sub)millimeter line emission, consistent with the dust continuum results. Our data suggest that G11.92–0.61-MM2 is the best candidate for a bonafide massive prestellar core found to date, and a promising target for future higher-sensitivity observations.« less
Authors:
 [1] ; ; ;  [2] ; ; ;  [3] ;  [4] ;  [5]
  1. Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy, University of St. Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom)
  2. NRAO, 520 Edgemont Rd, Charlottesville, VA 22903 (United States)
  3. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
  4. School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom)
  5. Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)
Publication Date:
OSTI Identifier:
22364513
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 796; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; ENERGY SPECTRA; GHZ RANGE; INDEXES; LUMINOSITY; MASERS; MOLECULES; PROTOSTARS; RESOLUTION; SENSITIVITY; STAR EVOLUTION; STAR MODELS; STARS