Detecting embedded intermediate-mass stars using mid-infrared and HI 21 centimeter emission

摘要

A technique is presented to detect distant, young embedded B stars ( and possible clusters) from their imprint on the surrounding interstellar medium. H I 21 cm and (CO)-C-12 ( J = 1-0) line data from the Canadian Galactic Plane Survey are combined with mid-infrared images from the Midcourse Space Experiment (MSX) Galactic plane survey to detect the photodissociation regions (PDRs) and molecular gas associated with the embedded intermediate-mass stars. The technique has been applied to a section of the Galaxy covered by the (CO)-C-12 Five College Radio Astronomy Observatory outer Galaxy survey (102.degrees5 < l < 141.degrees5, -3.degrees0 < b < + 5.degrees4) and has led to the detection of 15 embedded intermediate-mass stars. The basic physical properties of the PDRs are presented and compared with PDR models. The PDR models, combined with previous observations of early-type Herbig Ae/Be stars and the nondetection of many of the sources in OH, H2O, and CH3OH surveys, imply that the objects are similar to10(6) yr old. The IRAS colors of the objects form a well-defined group and have been combined with (CO)-C-12 and MSX observations to identify approximately 100 additional IRAS sources within the survey area as possible embedded intermediate-mass stars. References: 47