Stellar photometry in nine fields around the giant elliptical galaxy M87 in the Virgo cluster is obtained from archival images of the Hubble Space Telescope. The resulting Hertzsprung-Russell diagrams show populated red-giant and AGB branches. The position of the tip the red-giant branch (the TRGB discontinuity) is found to vary with galactocentric distance. This variation can be interpreted as the effect of metal-rich red giants on the procedure of the measurement of the TRGB discontinuity or as a consequence of the existence of a weak gas-and-dust cloud around M87 extending out to 10’ along the galactocentric radius and causing I-band absorption of up to \(0\mathop .\limits^{\rm{m}} 2\) near the center of the galaxy. The TRGB stars located far fromtheM87 center yield an average distancemodulus of (m-M) = 30.91 ± 0.08, which corresponds to the distance of D = 15.4± 0.6Mpc. It is shown that stars in the field located between M86 and M87 galaxies at angular separations of 37’ and 40’ are not intergalactic stars, but belong to the M87 galaxy, i.e., that the stellar halo of this galaxy can be clearly seen at a galactocentric distance of 190 kpc. The distances are measured to four dwarf galaxies P4anon, NGC4486A, VCCA039, and dSph-D07, whose images can be seen in the fields studied. The first three galaxies are M87 satellites, whereas dSph-D07 is located at a greater distance and is a member of the M86 group.

中文翻译：

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距巨型椭圆星系M87的距离及其恒星子系统的大小

从哈勃太空望远镜的档案图像获得了处女座星团中巨大椭圆星系M87周围九个场的恒星光度法。生成的Hertzsprung-Russell图显示了红色巨型和AGB分支。发现红色巨型分支的尖端位置（TRGB不连续性）随半视距而变化。这种变化可以解释为富含金属的红色巨人对TRGB不连续性的测量过程的影响，或者是由于M87周围存在微弱的尘埃云的结果，该云团沿着半乳糖中心延伸至10'半径并导致I带吸收高达\（0 \ mathop。\ limits ^ {\ rm {m}} 2 \）在银河系中心附近。距M87中心较远的TRGB星产生的平均距离模（m - M）= 30.91±0.08，对应于D = 15.4±0.6Mpc的距离。结果表明，位于M86和M87星系之间，距角为37'和40'的场中的恒星不是星际星，而是属于M87星系，即，该星系的恒星晕可以清楚地看到准中心距为190 kpc。测量到四个矮星系P4anon，NGC4486A，VCCA039和dSph-D07的距离，这些星系的图像可以在研究的领域中看到。前三个星系是M87卫星，而dSph-D07位于更远的距离，并且是M86组的成员。