首页|Revisiting the Velocity Dispersion-Size Relation in Molecular Cloud Structures

Revisiting the Velocity Dispersion-Size Relation in Molecular Cloud Structures

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Structures in molecular ISM are observed to follow a power-law relation between the velocity dispersion and spatial size,known as Larson's first relation,which is often attributed to the turbulent nature of molecular ISM and imprints the dynamics of molecular cloud structures.Using the 13CO(J=1-0)data from the Milky Way Imaging Scroll Painting survey,we built a sample with 360 structures having relatively accurate distances obtained from either the reddened background stars with Gaia parallaxes or associated maser parallaxes,spanning from 0.4 to～15 kpc.Using this sample and about 0.3 million pixels,we analyzed the correlations between velocity dispersion,surface/column density,and spatial scales.Our structure-wise results show power-law indices smaller than 0.5 in both the σv-Reff and σv-Reff·Σ relations.In the pixel-wise results,the σpixv is statistically scaling with the beam physical size(Rs=ΘD/2)in form of σpixv ∝ Rs0.43±003.Meanwhile,σpixv in the inner Galaxy is statistically larger than the outer side.We also analyzed correlations between σpixv and the H2 column density N(H2),finding that σpixv stops increasing with N(H2)after ≳1022 cm-2.The structures with and without high-column-density(＞1022 cm-2)pixels show different σpixv ∝ N(H2)ξ relations,where the mean(std)ξ values are 0.38(0.14)and 0.62(0.27),respectively.

ISM:structureISM:kinematics and dynamicsradio lines:ISM

Haoran Feng、Zhiwei Chen、Zhibo Jiang、Yuehui Ma、Yang Yang、Shuling Yu、Dongqing Ge、Wei Zhou、Fujun Du、Chen Wang、Shiyu Zhang、Yang Su、Ji Yang

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Purple Mountain Observatory,Chinese Academy of Sciences,Nanjing 210023,China

University of Science and Technology of China,Chinese Academy of Sciences,Hefei 230026,China

Center for Astronomy and Space Sciences,China Three Gorges University,Yichang 443000,China

Center for Astrophysics,Guangzhou University,Guangzhou 510006,China

National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100101,China

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2024

10.1088/1674-4527/ad89a9

天文和天体物理学研究
中国科学院国家天文台

天文和天体物理学研究

CSTPCD
影响因子：0.406
ISSN：1674-4527
年,卷(期)：2024.24(11)