Filamentary structure and Keplerian rotation in the high-mass star-forming region G35.03+0.35 imaged with ALMA

Abstract

Context. Theoretical scenarios propose that high-mass stars are formed by disk-mediated accretion. Aims. To test the theoretical predictions on the formation of massive stars, we wish to make a thorough study at high-angular resolution of the structure and kinematics of the dust and gas emission toward the high-mass star-forming region G35.03+0.35, which harbors a disk candidate around a B-type (proto)star. Methods. We carried out ALMA Cycle 0 observations at 870 μm of dust of typical high-density, molecular outflow, and cloud tracers with resolutions of <0. 5. Complementary Subaru COMICS 25 μm observations were carried out to trace the mid-infrared emission toward this star-forming region. Results. The submillimeter continuum emission has revealed a filamentary structure fragmented into six cores, called A-F. The filament could be in quasi-equilibrium taking into account that the mass per unit length of the filament, 200-375 M /pc, is similar to the critical mass of a thermally and turbulently supported infinite cylinder, ∼335 M /pc. The cores, which are on average separated by ∼0.02 pc, have deconvolved sizes of 1300-3400 AU, temperatures of 35-240 K, H 2 densities >10 7 cm −3 , and masses in the range 1-5 M , and they are subcritical. Core A, which is associated with a hypercompact Hii region and could be the driving source of the molecular outflow observed in the region, is the most chemically rich source in G35.03+0.35 with strong emission of typical hot core tracers such as CH 3 CN. Tracers of high density and excitation show a clear velocity gradient along the major axis of the core, which is consistent with a disk rotating about the axis of the associated outflow. The PV plots along the SE-NW direction of the velocity gradient show clear signatures of Keplerian rotation, although infall could also be present, and they are consistent with the pattern of an edge-on Keplerian disk rotating about a star with a mass in the range 5-13 M . The high t ff /t rot ratio for core A suggests that the structure rotates fast and that the accreting material has time to settle into a centrifugally supported disk. Conclusions. G35.03+0.35 is one of the most convincing examples of Keplerian disks rotating about high-mass (proto)stars. This supports theoretical scenarios according to which high-mass stars, at least B-type stars, would form through disk-mediated accretion.

Chemical segregation in hot cores with disk candidates

“…The temperatures were modeled at 50 K and 100 K for all but C 17 O, which was modeled at 20 K and the source size was fixed at the measured extent of the 3σ emission. Several species were previously demonstrated to have quite extended emission (H 13 CO + , C 17 O, SiO) in Sánchez-Monge et al (2014); Beltrán et al (2014). A summary of the results for these species is in Table 6.…”

“…G35.20 has a bolometric luminosity of 3.0 × 10 4 L (Sánchez-Monge et al 2014) and has been previously studied in Sánchez-Monge et al (2013) and Sánchez-Monge et al (2014) where they report the detection of a large (r∼2500 AU) Keplerian disk around Core B and a tentative one in Core A. The bolometric luminosity of G35.03 is 1.2 × 10 4 L and was reported to have a Keplerian disk (r∼1400-2000 AU) around the hot core A in Beltrán et al (2014). 338083 5.9 ± 0.1 51.7 ± 0.9 2.7 ± 0.1 27.3 ± 1.0 2.4 ± 0.1 28 ± 1 2.54 ± 0.06 44.3 ± 0.9 6.6 ± 0.1 21.0 ± 0.3 10 1,9 -9 1,8 348532 5.8 ± 0.1 59.2 ± 1.3 2.6 ± 0.1 31 ± 1 2.3 ± 0.1 31 ± 1 2.58 ± 0.04 52.1 ± 0.7 6.33 ± 0.09 21.3 ± 0.3 H 2 C 33 S 10 1,10 -9 1,9 335160 7.5 ± 0.2 3.91 ± 0.09 1.6 ± 0.5 0.4 ± 0.1 1.5 ± 0.6 0.4 ± 0.2 2.5 ±0.2 1.47 ± 0.08 < 3σ H 2 C 34 S 10 0,10 -9 0,9 337125 blended 1.2 ± 0.7 0.7 ± 0.4 1.5 ± 0.2 1.0 ± 0.1 1.9 ± 0.1 2.5 ± 0.1 < 3σ 10 4,6 -9 4,5 337460 blended with CH 3 OH ν=1 in abs.…”

“…The pixel-sized colored square marks the spectral extraction point. The cores identified in Beltrán et al (2014) are labeled A-F.…”

“…The digital correlator was configured in four spectral windows (with dual polarization) of 1875 MHz and 3840 channels each, providing a resolution of ∼0.4 km/s. The four spectral windows covered the frequency ranges [336 849.57-338 Sánchez-Monge et al (2014) and Beltrán et al (2014).…”

A Face-on Accretion System in High-mass Star Formation: Possible Dusty Infall Streams within 100 AU

“…Almost all of the known circumstellar systems in High-Mass star-formation are in a nearly edgeon orientation (e.g., Patel et al 2005;Torrelles et al 2007;Matthews et al 2010;Carrasco-González et al 2012;Sánchez-Monge et al 2013;Beltrán et al 2014;Cesaroni et al 2014;Hirota et al 2016Hirota et al , 2017Plambeck & Wright 2016). This bias is simply due to their easy identification even with limited angular resolution, based on the velocity gradient of rotating disks and/or envelopes.…”