Dust in Cluster Dwarf Elliptical Galaxies

摘要

Based on single cross-scan data of the Herschel Virgo Cluster Survey, we report the first detections of dust in cluster early-type dwarf galaxies: VCC 209, VCC781 and VCC 951. All three galaxies have dust masses M_d ≈ 10~5 - 10~6 M_☉ and average dust temperatures ≈ 16-20 K. Since these three early-type dwarfs reside in densely crowded regions close to the center of the Virgo cluster, and several Hi-detected dwarfs in the outskirts of Virgo were not detected by Herschel (implying a dust content <10~4 M_☉), this might imply that dust in dwarfs is more closely related to the molecular gas, which is more centrally peaked in a galaxy's potential well and therefore, not easily removed by any stripping mechanism. We conclude that the removal of interstellar dust from these early-type dwarfs appears to be less efficient than the removal of the Hi gas.