无恒星星系候选体Cloud-9的超深度成像
Ultra-Deep imaging of the starless galaxy candidate Cloud-9
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中文总结 AI 辅助
研究人员通过GTC的HiPERCAM超深度成像未检测到暗星系候选体Cloud-9的恒星光，结合积分光约束，进一步支持其为无恒星星系候选体的结论。
中文摘要 AI 辅助
我们报告未检测到与暗星系候选体Cloud-9相关的恒星光。使用加那利大型望远镜（GTC）上的HiPERCAM获得的超深度成像，在g波段和r波段分别达到31.4和31.0 mag/arcsec²的表面亮度极限，比该区域此前的深成像深约10倍。在Cloud-9中心1'×1'（约1.3×1.3千秒差距）区域内未检测到恒星发射。假设存在古老、贫金属的恒星族群，这些极限意味着恒星表面质量密度不超过约0.01 M☉/pc²，总恒星质量上限为1.6×10⁴ M☉。这种来自积分光的独立约束补充了此前基于分辨恒星计数的极限，进一步支持Cloud-9作为无恒星星系候选体的结论。
英文摘要
We report the non-detection of stellar light associated with the dark galaxy candidate Cloud-9. Ultra-deep imaging obtained with HiPERCAM at the Gran Telescopio Canarias (GTC) reaches surface-brightness limits of 31.4 and 31.0 mag/arcsec$^2$ in g and r, respectively, approximately ten times deeper than previous deep imaging of the region. No stellar emission is detected within the central 1'$\times$1' ($\sim$1.3$\times$1.3 kpc) region of Cloud-9. Assuming an old, metal-poor stellar population, these limits imply a stellar surface mass density of no more than $\sim$0.01 M$_\odot$/pc$^2$ and an upper limit on the total stellar mass of 1.6$\times$10$^4$ M$_\odot$. This independent constraint from integrated light complements previous limits based on resolved-star counts and strengthens the case for Cloud-9 as a candidate starless galaxy.
