A Nascent Tidal Dwarf Galaxy Forming within the Northern H i Streamer of M82
Abstract We identify a ∼600 pc wide region of active star formation located within a tidal streamer of M82 via H α emission ( F H α ∼ 6.5 × 10 −14 erg s −1 cm −2 ), using a pathfinder instrument based on the Dragonfly Telephoto Array. The object is kinematically decoupled from the disk of M82 as confirmed via Keck/LRIS spectroscopy and is spatially and kinematically coincident with an overdensity of H i and molecular hydrogen within the “northern H i streamer” induced by the passage of M81 several hundred Myr ago. From H i data, we estimate that ∼5 × 10 7 M ⊙ of gas is present in the specific overdensity coincident with the H α source. The object’s derived metallicity (12+ log ( O / H ) ≃ 8.6 ), position within a gas-rich tidal feature, and morphology (600 pc diameter with multiple star-forming clumps), indicate that it is likely a tidal dwarf galaxy in the earliest stages of formation.
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Publication Date:
NSF-PAR ID:
10320261
Journal Name:
The Astrophysical Journal Letters
Volume:
923
Issue:
2
ISSN:
2041-8205
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