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http://hdl.handle.net/20.500.12386/28773
Titolo: | HST Resolves Stars in a Tiny Body Falling on the Dwarf Galaxy DDO 68 | Autori: | ANNIBALI, FRANCESCA BELLAZZINI, Michele Correnti, M. Sacchi, E. TOSI, Monica Cignoni, M. Aloisi, A. Calzetti, D. Ciotti, L. CUSANO, FELICE Lee, J. Nipoti, C. |
Data pubblicazione: | 2019 | Rivista: | THE ASTROPHYSICAL JOURNAL | Numero: | 883 | Fascicolo: | 1 | Da pagina:: | 19 | Abstract: | We present new Hubble Space Telescope imaging of a stream-like system associated with the dwarf galaxy DDO 68, located in the Lynx-Cancer void at a distance of D ∼ 12.65 Mpc from us. The stream, previously identified in deep Large Binocular Telescope images as a diffuse low surface brightness structure, is resolved into individual stars in the F606W (broad V) and F814W (∼I) images acquired with the Wide Field Camera 3. The resulting V, I color-magnitude diagram (CMD) of the resolved stars is dominated by old (age ≳ 1-2 Gyr) red giant branch (RGB) stars. From the observed RGB tip, we conclude that the stream is at the same distance as DDO 68, confirming the physical association with it. A synthetic CMD analysis indicates that the large majority of the star formation activity in the stream occurred at epochs earlier than ∼1 Gyr ago, and that the star formation at epochs more recent than ∼500 Myr ago is compatible with zero. The total stellar mass of the stream is ∼10<SUP>6</SUP> M <SUB>☉</SUB>, about 1/100 of that of DDO 68. This is a striking example of hierarchical merging in action at the dwarf galaxy scales. | URI: | http://hdl.handle.net/20.500.12386/28773 | URL: | https://iopscience.iop.org/article/10.3847/1538-4357/ab3409 | ISSN: | 0004-637X | DOI: | 10.3847/1538-4357/ab3409 | Bibcode ADS: | 2019ApJ...883...19A | Fulltext: | open |
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