文章基本信息

标题：The Giant Herbig–Haro Flow HH 212 and Associated Star Formation
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作者：Bo Reipurth ; C. J. Davis ; John Bally 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2019
卷号：158
期号：3
页码：1-11
DOI：10.3847/1538-3881/ab2d25
语种：English
出版社：American Institute of Physics
摘要：The bipolar jet HH212 is one of the finest collimated jets known. It has up to now been detected only in near-infrared H 2 emission, but here we present deep optical images that show that two of the major bow shocks are weakly detected in optical [S II ] emission, as expected for a bona fide Herbig–Haro jet. We also present widefield H 2 images that reveal two more bow shocks located symmetrically to the north and south around the source and along the main jet axis. Additionally, examination of Spitzer 4.5μm images reveals yet another bright bow shock further to the north along the jet axis; no corresponding bow shock is seen to the south. In total, the HH212 flow has an extent of 1050″, corresponding to a projected dimension of 2.0pc. HH212 thus joins the growing group of parsec-scale Herbig–Haro jets. Proper motion measurements indicate a velocity of about 170 kms −1 , highly symmetric around the source, with an uncertainty of ∼30 kms −1 , suggesting a probable age of the giant HH212 flow of about 7000yr. The jet is driven by a deeply embedded source, known as IRAS05413–0104. We draw attention to a Spitzer near- and mid-infrared source, which we call IRS-B, located only 7″ from the driving source, toward the outskirts of the dense cloud core. Infrared photometry and spectroscopy suggests that IRS-B is a K-type star with a substantial infrared excess, except that for an extinction of A V =44 the star would have only a weak infrared excess, and so in principle it could be a K-giant at a distance of about 2kpc. Finally, we have identified a ClassII source and a ClassI source about 21/2′ SSW of IRAS05413–0104, indicating that additional star formation has taken place in the cloud, and that the HH212 star-forming event is not as isolated as sometimes considered.
关键词：stars: formation;stars: low-mass;stars: pre-main sequence;stars: protostars