TY - JOUR
T1 - The Elephant Trunk Nebula and the Trumpler 37 cluster
T2 - Contribution of triggered star formation to the total population of an Hii region
AU - Getman, Konstantin V.
AU - Feigelson, Eric D.
AU - Sicilia-Aguilar, Aurora
AU - Broos, Patrick S.
AU - Kuhn, Michael A.
AU - Garmire, Gordon P.
PY - 2012/11/11
Y1 - 2012/11/11
N2 - Rich young stellar clusters produce Hii regions whose expansion into the nearby molecular cloud is thought to trigger the formation of new stars. However, the importance of this mode of star formation is uncertain. This investigation seeks to quantify triggered star formation (TSF) in IC 1396A (aka the Elephant Trunk Nebula), a bright-rimmed cloud (BRC) on the periphery of the nearby giant Hii region IC 1396 produced by the Trumpler 37 cluster. X-ray selection of young stars from Chandra X-ray Observatory data is combined with existing optical and infrared surveys to give a more complete census of the TSF population. Over 250 young stars in and around IC 1396A are identified; this doubles the previously known population. A spatio-temporal gradient of stars from the IC 1396A cloud towards the primary ionizing star HD 206267 is found. We argue that the TSF mechanism in IC 1396A is a radiation-driven implosion process persisting over several million years. Analysis of the X-ray luminosity and initial mass functions indicates that >140 stars down to 0.1M⊙ were formed by TSF. Considering other BRCs in the IC 1396 Hii region, we estimate the TSF contribution for the entire Hii region exceeds 14-25 per cent today, and may be higher over the lifetime of the Hii region. Such triggering on the periphery of Hii regions may be a significant mode of star formation in the Galaxy.
AB - Rich young stellar clusters produce Hii regions whose expansion into the nearby molecular cloud is thought to trigger the formation of new stars. However, the importance of this mode of star formation is uncertain. This investigation seeks to quantify triggered star formation (TSF) in IC 1396A (aka the Elephant Trunk Nebula), a bright-rimmed cloud (BRC) on the periphery of the nearby giant Hii region IC 1396 produced by the Trumpler 37 cluster. X-ray selection of young stars from Chandra X-ray Observatory data is combined with existing optical and infrared surveys to give a more complete census of the TSF population. Over 250 young stars in and around IC 1396A are identified; this doubles the previously known population. A spatio-temporal gradient of stars from the IC 1396A cloud towards the primary ionizing star HD 206267 is found. We argue that the TSF mechanism in IC 1396A is a radiation-driven implosion process persisting over several million years. Analysis of the X-ray luminosity and initial mass functions indicates that >140 stars down to 0.1M⊙ were formed by TSF. Considering other BRCs in the IC 1396 Hii region, we estimate the TSF contribution for the entire Hii region exceeds 14-25 per cent today, and may be higher over the lifetime of the Hii region. Such triggering on the periphery of Hii regions may be a significant mode of star formation in the Galaxy.
UR - http://www.scopus.com/inward/record.url?scp=84867858577&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84867858577&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2966.2012.21879.x
DO - 10.1111/j.1365-2966.2012.21879.x
M3 - Article
AN - SCOPUS:84867858577
SN - 0035-8711
VL - 426
SP - 2917
EP - 2943
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 4
ER -