Poster abstract
A deep Chandra observation of the S254-S258 star forming complex
Abstract
In the S254--S258 region a dense cluster of very young stellar objects is
sandwiched between two HII regions. This remarkable configuration has led to conjectures that the two B stars exciting the HII regions may have been dynamically ejected from the central cluster, or, alternatively, that the current star formation activity in the central cloud is triggered at the intersection of the two expanding HII regions. In the second case, the two B stars should belong to a slightly (few Myr) older stellar generation, but, interestingly, no associated young low-mass stars could be identified so far around them; this lead to speculations of a case of isolated formation of massive stars.
In order to solve this puzzle, we have performed a deep Chandra X-ray
observation of this extraordinary star forming region and detected more than 360 X-ray sources. This yields, for the first time, a reasonably complete sample of all young stars in the region, avoiding the usual bias introduced when selecting samples based only on infrared excess. We will present the first results of our ongoing analysis. Combination of our X-ray catalog with optical and infrared data allows us to study the stellar properties of the young objects and to infer the star formation history of this interesting region.
sandwiched between two HII regions. This remarkable configuration has led to conjectures that the two B stars exciting the HII regions may have been dynamically ejected from the central cluster, or, alternatively, that the current star formation activity in the central cloud is triggered at the intersection of the two expanding HII regions. In the second case, the two B stars should belong to a slightly (few Myr) older stellar generation, but, interestingly, no associated young low-mass stars could be identified so far around them; this lead to speculations of a case of isolated formation of massive stars.
In order to solve this puzzle, we have performed a deep Chandra X-ray
observation of this extraordinary star forming region and detected more than 360 X-ray sources. This yields, for the first time, a reasonably complete sample of all young stars in the region, avoiding the usual bias introduced when selecting samples based only on infrared excess. We will present the first results of our ongoing analysis. Combination of our X-ray catalog with optical and infrared data allows us to study the stellar properties of the young objects and to infer the star formation history of this interesting region.