Age Sequence in Small Clusters Associated with Bright-Rimmed Clouds

[摘要] Bright-rimmedclouds(BRCs)foundinHIIregionsareprobablesitesoftriggeredstarformationduetocompressionbyionization/shockfronts,anditishypothesizedthatstarformationproceedsfromtheexcitingstar(s)sideoutwardoftheHIIregion(“small-scalesequentialstarformation”).Inordertoquantitativelytestthishypothesisweundertook$$BVI_mathrm{c}$$photometryoffourBRCaggregates.Theamountsofinterstellarextinctionandreddeningforeachstarwereestimatedbyusing$$JHK_mathrm{s}$$photometry.Wethenconstructedreddening-corrected$$V/V-I_mathrm{c}$$color-magnitudediagrams,wheretheageofeachstarwasderived.AllofthestarsturnedouttobeafewtenthstoafewMyrold.Althoughthescatterswerelargeandthenumbersofthesamplestarsaresmall,wefoundacleartrendthatthestarsinsideorintheimmediatevicinityofthebrightrimareyoungerthanthoseoutsideitinallfouraggregates,confirmingthehypothesisinquestion.

[学科分类] 天文学(综合)

[关键词] "open clusters and associations: general";"ISM: bubbles";"HII regions";"stars: formation";"stars: pre-main sequence"