We present a multitracer analysis of the Sh2-252 A-B(S252 A-B)star-forming molecular clump located between H Ⅱ regions S252A and S252B,using molecular line observations(CO isotopologues and NH3)and far-infrared dust ...We present a multitracer analysis of the Sh2-252 A-B(S252 A-B)star-forming molecular clump located between H Ⅱ regions S252A and S252B,using molecular line observations(CO isotopologues and NH3)and far-infrared dust continuum data to study star formation mechanisms in S252 A-B.We find evidence for existence of a hubfilament system(HFS)in this area.Our observations reveal six filaments converging upon a main S252A-B and secondary S252A hubs.The region was previously suspected as a site of cloud–cloud collision(CCC).However,the only observed double-peaked spectra are located at the south-western edge of S252 A-B and show no associated young stellar objects(YSOs),suggesting that star formation in the S252 A-B region is not induced by CCC.The filaments have clear association with the YSOs and their clusters.Filaments remain cold(Tkin≈15–18 K)until merging with the hub,demonstrating“shielded flow.”The virial parameter(αvir∼0.4–0.6)indicates that the hub is gravitationally bound.We conclude that S252 A-B possesses an active HFS and star formation in the region is driven by global hierarchical collapse.Two filaments located at the borders of the large H Ⅱ region S252 may be prone to the collect-and-collapse process,highlighting how feedback-driven compression and gravitational focusing work in accord to bring mass to the sites of active star formation.展开更多
基金funded by Xinjiang Key Laboratory of Radio Astrophysics under grant 2023D04033National Key R&D Program of China under grant(Nos.2022YFA1603103 and 2023YFA1608002)+10 种基金funded by the Tianshan Talent Training Program 2024TSYCTD0013the National Natural Science Foundation of China(NSFC,grant Nos.12173075,12373029,12103082 and 12403033)XBZG-ZDSYS-202212.G.W.was supported by the Xinjiang Tianchi Talents Program,the National SKA Program of China 2025SKA0140100the Youth Innovation Promotion Association CAS,the CASANSO Fellowship.grant No.CAS-ANSO-FA-2024-06the Tianchi Talent Project of Xinjiang Uyghur Autonomous Region,the Central Guidance for Local Science and Technology Development Fund ZYYD2025ZY23the Natural Science Foundation of Xinjiang Uygur Autonomous Region under grant Nos.2022D01E06,2022D01A359 and 2023D01A11supported by the Ministry of Science and Higher Education of the Russian Federation(theme No.FEUZ-2026-0012)funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan(grant No.AP26102915)funded by the Chinese Academy of Sciences President’s International Fellowship Initiative grant No.2024VMA0002The Nanshan 26 m Radio Telescope and is partly supported by the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administrated by the Chinese Academy of Sciences(CAS)the Urumqi Nanshan Astronomy and Deep Space Exploration Observation and Research Station of Xinjiang(XJYWZ2303).
文摘We present a multitracer analysis of the Sh2-252 A-B(S252 A-B)star-forming molecular clump located between H Ⅱ regions S252A and S252B,using molecular line observations(CO isotopologues and NH3)and far-infrared dust continuum data to study star formation mechanisms in S252 A-B.We find evidence for existence of a hubfilament system(HFS)in this area.Our observations reveal six filaments converging upon a main S252A-B and secondary S252A hubs.The region was previously suspected as a site of cloud–cloud collision(CCC).However,the only observed double-peaked spectra are located at the south-western edge of S252 A-B and show no associated young stellar objects(YSOs),suggesting that star formation in the S252 A-B region is not induced by CCC.The filaments have clear association with the YSOs and their clusters.Filaments remain cold(Tkin≈15–18 K)until merging with the hub,demonstrating“shielded flow.”The virial parameter(αvir∼0.4–0.6)indicates that the hub is gravitationally bound.We conclude that S252 A-B possesses an active HFS and star formation in the region is driven by global hierarchical collapse.Two filaments located at the borders of the large H Ⅱ region S252 may be prone to the collect-and-collapse process,highlighting how feedback-driven compression and gravitational focusing work in accord to bring mass to the sites of active star formation.
