论文标题
M31和M33郊区的灰尘
Dust in the outskirts of M31 and M33
论文作者
论文摘要
M31和M33是研究螺旋星系郊区灰尘分布的理想场所。在这封信中，使用大约20万星，从lamost数据中选择并结合了Gaia Dr2的精确光度法和可视性，我们已经构建了一个二维前景灰尘粉红色的地图，向M31和M33区域（$ 111.2°{\ le} gl} gl {\ le} gl {\ le} 136.2°，-36.56.5。 -16.5°$）。该地图的空间分辨率约为12分钟，精度为0.01 mag。揭示了朝向M31的尘埃云的复杂结构。通过小心地从Schlegel等人的灰尘变红地图中删除前景灭绝。 （1998年），我们获得了一个残留图来研究M31和M33郊区的灰尘分布。在M31光环中检测到大量灰尘，距离超过100 kpc。发现M31磁盘中的灰尘延伸至其光度半径的2.5倍，其分布与尺度长度为7.2 kpc或两个磁盘的指数盘在其光度半径内的比例长度为11.1 kpc，并且超过其光度radius。还发现M33磁盘中的灰尘延伸至其光度半径的2.5倍，其分布超过一个光radius，与规模长度为5.6 kpc的指数盘一致。我们的结果为星系中灰尘的分布和循环提供了新的线索。
M31 and M33 serve as ideal places to study distributions of dust in the outskirts of spiral galaxies. In this letter, using about 0.2 million stars selected from the LAMOST data and combining precise photometry and parallaxes from the Gaia DR2, we have constructed a two-dimensional foreground dust reddening map towards the M31 and M33 region ($111.2° {\le} gl {\le} 136.2°, -36.5° {\le} gb {\le} -16.5°$). The map has a typical spatial resolution of about 12 arc-minute and precision of 0.01 mag. The complex structure of dust clouds towards the M31 is revealed. By carefully removing the foreground extinction from the dust reddening map of Schlegel et al. (1998), we thus have obtained a residual map to study dust distributions in the outskirts of M31 and M33. A large amount of dust is detected in the M31 halo out to a distance of over 100 kpc. Dust in the M31 disk is found to extend out to about 2.5 times its optical radius, whose distribution is consistent with either an exponential disk of scale length of 7.2 kpc or two disks with scale length of 11.1 kpc within its optical radius and 18.3 kpc beyond its optical radius. Dust in the disk of M33 is also found to extend out to about 2.5 times its optical radius, its distribution beyond one optical radius is consistent with an exponential disk of scale length of 5.6 kpc. Our results provide new clues on the distributions and cycling of dust in galaxies.
