Two extreme young objects in Barnard 1-b

Journal Article · Tue Jul 01 04:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/789/1/50· OSTI ID:22356486

Hirano, Naomi ^[1]; Liu, Fang-chun ^[2]

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1. Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, National Taiwan University, No 1, Sec. , Roosevelt Road, Taipei, 10617 Taiwan (China)
2. Max Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)

Two submillimeter/millimeter sources in the Barnard 1b (B1-b) core, B1-bN and B1-bS, have been studied in dust continuum, H{sup 13}CO{sup +} J = 1-0, CO J = 2-1, {sup 13}CO J = 2-1, and C{sup 18}O J = 2-1. The spectral energy distributions of these sources from the mid-IR to 7 mm are characterized by very cold temperatures of T {sub dust} < 20 K and low bolometric luminosities of 0.15-0.31 L {sub ☉}. The internal luminosities of B1-bN and B1-bS are estimated to be <0.01-0.03 L {sub ☉} and ∼0.1-0.2 L {sub ☉}, respectively. Millimeter interferometric observations have shown that these sources have already formed central compact objects of ∼100 AU sizes. Both B1-bN and B1-bS are driving the CO outflows with low characteristic velocities of ∼2-4 km s{sup –1}. The fractional abundance of H{sup 13}CO{sup +} at the positions of B1-bN and B1-bS is lower than the canonical value by a factor of four to eight. This implies that a significant fraction of CO is depleted onto dust grains in the dense gas surrounding these sources. The observed physical and chemical properties suggest that B1-bN and B1-bS are in an earlier evolutionary stage than most of the known class 0 protostars. In particular, the properties of B1-bN agree with those of the first hydrostatic core predicted by the MHD simulations. The CO outflow was also detected in the mid-IR source located at ∼15'' from B1-bS. Since the dust continuum emission was not detected in this source, the circumstellar material surrounding this source is less than 0.01 M {sub ☉}. It is likely that the envelope of this source was dissipated by the outflow from the protostar that is located to the southwest of B1-b.

• OSTI ID: 22356486
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 789; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
BOLOMETERS
CARBON MONOXIDE
DUSTS
EMISSION
ENERGY SPECTRA
LUMINOSITY
MAGNETOHYDRODYNAMICS
PROTOSTARS
SIMULATION
STARS
VELOCITY