SIMBAD references

2012ApJ...745..117B - Astrophys. J., 745, 117 (2012/February-1)

Initial conditions for star formation in clusters: physical and kinematical structure of the starless core Oph A-N6.


Abstract (from CDS):

We present high spatial (<300 AU) and spectral (0.07 km/s) resolution Submillimeter Array observations of the dense starless cluster core Oph A-N6 in the 1 mm dust continuum and the 3-2 line of N2H+ and N2D+. The dust continuum observations reveal a compact source not seen in single-dish observations, of size ∼1000 AU and mass 0.005-0.01 M. The combined line and single-dish observations reveal a core of size 3000x1400 AU elongated in a NW-SE direction, with almost no variation in either line width nor line center velocity across the map, and very small non-thermal motions. The deuterium fraction has a peak value of ∼0.15 and is >0.05 over much of the core. The N2H+ column density profile across the major axis of Oph A-N6 is well represented by an isothermal cylinder, with temperature 20 K, peak density 7.1x106/cm3, and N2H+ abundance 2.7x10–10. The mass of Oph A-N6 is estimated to be 0.29 M, compared to a value of 0.18 M from the isothermal cylinder analysis, and 0.63 Mfor the critical mass for fragmentation of an isothermal cylinder. Compared to isolated low-mass cores, Oph A-N6 shows similar narrow line widths and small velocity variation, with a deuterium fraction similar to "evolved" dense cores. It is significantly smaller than isolated cores, with larger peak column and volume density. The available evidence suggests that Oph A-N6 has formed through the fragmentation of the Oph A filament and is the precursor to a low-mass star. The dust continuum emission suggests that it may already have begun to form a star.

Abstract Copyright:

Journal keyword(s): ISM: individual: Oph A-N6 - stars: formation - stars: low-mass

Simbad objects: 25

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