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Aims. Studying protostellar objects in their earliest stages, particularly during the Class 0 phase, provides key insight into the beginnings of planet formation and dust evolution. Disentangling the various components, however, is…

We present the results of a single dish survey toward 95 VeLLOs in optically thick (HCN 1-0) and thin ($\rm N_2H^+$ 1-0) lines performed for the purpose of understanding the physical processes of inward motions in the envelopes of the…

Astrophysics of Galaxies · Physics 2021-04-14 Mi-Ryang Kim , Chang Won Lee , Maheswar , G , Philip C. Myers , Gwanjeong Kim

We present $^{29}$SiO(J=8--7) $\nu$=0, SiS (J=19--18) $\nu$=0, and $^{28}$SiO (J=8--7) $\nu$=1 molecular line archive observations made with the Atacama Large Millimeter/Submillimeter Array (ALMA) of the molecular outflow associated with…

Solar and Stellar Astrophysics · Physics 2020-12-09 J. A. López-Vázquez , Luis A. Zapata , Susana Lizano , Jorge Cantó

To assess the potential role of magnetic fields in regulating the envelope rotation and the fragmentation of Class 0 protostars, we carried out observations of the dust polarized emission at 0.87 mm with the SMA, in the envelopes of a large…

HH 212 is a highly collimated jet discovered in H2 powered by a young Class 0 source, IRAS 05413-0104, in the L1630 cloud of Orion. We have mapped around it in 1.33 mm continuum, 12CO ($J=2-1$), 13CO ($J=2-1$), C18O ($J=2-1$), and SO ($J_K…

(abridged) We aim to characterize kinematic processes in the G012.80 protocluster. We principally focus on the N$_2$H$^+$(1$-$0) emission to trace the dense and cold gas. Additionally, we use lines such as DCN(3$-$2), H41$\alpha$,…

We present 3 mm ALMA continuum and line observations at resolutions of 6.5 au and 13 au respectively, toward the Class 0 system IRAS 16293-2422 A. The continuum observations reveal two compact sources towards IRAS 16293-2422 A, coinciding…

We present a multi-wavelength observational study of a low-mass star-forming region, L1251-C, with observational results at wavelengths from the near-infrared to the millimeter. Spitzer Space Telescope observations confirmed that IRAS…

Observations of dense molecular gas lie at the basis of our understanding of the density and temperature structure of protostellar envelopes and molecular outflows. We aim to characterize the properties of the protostellar envelope,…

Solar and Stellar Astrophysics · Physics 2015-05-14 T. A. van Kempen , E. F. van Dishoeck , M. R. Hogerheijde , R. Guesten

We present the results of a study aimed at assessing whether low and high mass stars form similarly. Our approach is (1) to examine the observed projected rotational velocities among a large sample of newly-formed stars spanning a range in…

Astrophysics · Physics 2008-11-26 S. C. Wolff , S. E. Strom , D. Dror , L. Lanz , K. Venn

Understanding the formation pathway for close-companion protostars is central to unraveling the processes that govern stellar multiplicity and very early star formation. We analyze a large sample of 51 Class 0/I close-companion protostellar…

We numerically investigate the dynamics of a 2D non-magnetised protoplanetary disc surrounded by an inflow coming from an external envelope. We find that the accretion shock between the disc and the inflow is unstable, leading to the…

Solar and Stellar Astrophysics · Physics 2015-10-14 Geoffroy Lesur , Patrick Hennebelle , Sébastien Fromang

We present the results of an interferometric study of the N2H+(1--0) emission from nine nearby, isolated, low-mass protostellar cores, using the OVRO millimeter array. The main goal of this study is the kinematic characterization of the…

Astrophysics · Physics 2009-11-13 Xuepeng Chen , Ralf Launhardt , Thomas Henning

The massive young stellar object S255IR NIRS3 embedded in the star forming core SMA1 has been recently observed with a luminosity burst, which is conjectured as a disc-mediated variable accretion event. In this context, it is imperative to…

Astrophysics of Galaxies · Physics 2020-12-09 Sheng-Yuan Liu , Yu-Nung Su , Igor Zinchenko , Kuo-Song Wang , Dominique M. -A. Meyer , Yuan Wang , I-Ta Hsieh

We present CARMA CO (J=1-0) observations and Herschel PACS spectroscopy, characterizing the outflow properties toward extremely young and deeply embedded protostars in the Orion molecular clouds. The sample comprises a subset of the Orion…

The formation process of high-mass stars (>8M$_\odot$) is poorly constrained, particularly, the effects of clump fragmentation creating multiple systems and the mechanism of mass accretion onto the cores. We study the fragmentation of dense…

This paper presents the first substantial study of the chemistry of the envelopes around a sample of 18 low-mass pre- and protostellar objects for which physical properties have previously been derived from radiative transfer modeling of…

Astrophysics · Physics 2009-11-10 J. K. Jorgensen , F. L. Schoeier , E. F. van Dishoeck

Rotation is expected to have an important influence on the structure and the evolution of stars. However, the mechanisms of angular momentum transport in stars remain theoretically uncertain and very complex to take into account in stellar…

Gravitational accretion accumulates the original mass, and this process is crucial for us to understand the initial phases of star formation. Using the specific infall profiles in optically thick and thin lines, we searched the clumps with…

Astrophysics of Galaxies · Physics 2020-09-02 Yang Yang , Zhibo Jiang , Zhiwei Chen , Shaobo Zhang , Shuling Yu , Yiping Ao

We test the effect of assumptions about stellar motion on the behavior of gravitational instabilities in protoplanetary disks around solar-type stars by performing two simulations that are identical in all respects except the treatment of…

Earth and Planetary Astrophysics · Physics 2015-03-17 Scott Michael , R. H. Durisen