We present results from ground-based optical imaging of a low-mass dwarf galaxy discovered by the ALFALFA 21?cm H I survey. Broadband (BVR) data obtained with the WIYN 3.5?m telescope at Kitt Peak National Observatory (KPNO) are used to construct color-magnitude diagrams of the galaxy's stellar population down to Vo ~ 25. We also use narrowband Hα imaging from the KPNO 2.1?m telescope to identify a H II region in the galaxy. We use these data to constrain the distance to the galaxy to be between 1.5 and 2.0?Mpc. This places Leo P within the Local Volume but beyond the Local Group. Its properties are extreme: it is the lowest-mass system known that contains significant amounts of gas and is currently forming stars.
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机译：我们介绍了ALFALFA 21？cm H I调查发现的低质量矮星系的地面光学成像结果。在基特峰国家天文台（KPNO）使用WIYN 3.5？m望远镜获得的宽带（BVR）数据用于构建低至Vo〜25的星系恒星种群的色度图。我们还从KPNO 2.1使用窄带Hα成像。 ？m望远镜确定星系中的H II区域。我们使用这些数据将到银河系的距离限制在1.5至2.0？Mpc之间。这会将Leo P放置在本地卷中，但不在本地组中。它的特性是极端的：它是已知的质量最低的系统，其中包含大量的气体，目前正在形成恒星。
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