2023/01/17 by Sai, Jinshi, Ohashi, Nagayoshi, Yen, Hsi-Wei +2 · 1 citation
#Astrophysics of Galaxies (astro-ph.GA) #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR)
paper · doi:10.48550/arxiv.2301.06969
We have observed the three low-mass protostars, IRAS 15398-3359, L1527 IRS and TMC-1A, with the ALMA 12-m array, the ACA 7-m array, and the IRAM-30m and APEX telescopes in the C18O J=2-1 emission. Overall, the C18O emission shows clear velocity gradients at radii of ∼100-1000 au, which likely originate from rotation of envelopes, while velocity gradients are less clear and velocity structures are more perturbed on scales of ∼1000-10,000 au. IRAS 15398-3359 and L1527 IRS show a break at radii of ∼1200 and ∼1700 au in the radial profile of the peak velocity, respectively. The peak velocity is proportional to r-1.38 or r-1.7 within the break radius, which can be interpreted as indicating a rotational motion of the envelope with a degree of contamination of gas motions on larger spatial scales. The peak velocity follows vpeak ∝ r0.68 or vpeak ∝ r0.46 outside the break radius, which is similar to the J/M-R relation of dense cores. TMC-1A exhibits the radial profile of the peak velocity not consistent with the rotational motion of the envelope nor the J/M-R relation. The origin of the relation of vpeak ∝ r0.46-0.68 is investigated by examining correlations of the velocity deviation (δv) and the spatial scale (τ) in the two sources. Obtained spatial correlations, δv ∝ τ∼0.6, are consistent with the scaling law predicted by turbulence models, which may suggest the large-scale velocity structures originate from turbulence.