HST Resolves Stars in a Tiny Body Falling on the Dwarf Galaxy DDO 68
HST Resolves Stars in a Tiny Body Falling on the Dwarf Galaxy DDO 68
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HST 解析了落在矮星系 DDO 68 上的微小物体中的恒星
DOI：
10.3847/1538-4357/ab3409
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
C. Nipoti
中科院分区：
文献类型：
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作者：
F. Annibali;M. Bellazzini;M. Correnti;E. Sacchi;M. Tosi;M. Cignoni;A. Aloisi;D. Calzetti;L. Ciotti;F. Cusano;J. Lee;C. Nipoti
我们展示了哈勃太空望远镜拍摄的与矮星系DDO 68有关的流状系统的新图像，该系统位于距我们D ~ 12.65 Mpc的猞猁-巨蟹座空区。先前在深大双筒望远镜图像中被识别为弥漫性低表面亮度结构的流，在广角相机3获得的F606W（宽V）和F814W （~ I）图像中被分解成单个恒星。得到的V、I色星等图（CMD）主要是年龄≥1 - 2gyr的老红巨星分支（RGB）恒星。从观察到的RGB尖端，我们得出结论，该流与DDO 68处于相同的距离，证实了与它的物理关联。综合CMD分析表明，流中绝大多数恒星形成活动发生在早于~ 1 Gyr以前的时代，而最近于~ 500 Myr以前的时代的恒星形成与零相容。该星系流的恒星总质量约为106M⊙，约为DDO 68的1/100。这是一个引人注目的矮星系等级合并的例子。
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 ∼106M⊙, about 1/100 of that of DDO 68. This is a striking example of hierarchical merging in action at the dwarf galaxy scales.
影响因子：
4.8
作者：
Coral Wheeler;P. Hopkins;A. Pace;S. Garrison-Kimmel;M. Boylan-Kolchin;A. Wetzel;J. Bullock;D. Keres
通讯作者：
Coral Wheeler;P. Hopkins;A. Pace;S. Garrison-Kimmel;M. Boylan-Kolchin;A. Wetzel;J. Bullock;D. Keres