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Discovery of an Extraordinarily Massive Young Stellar Cluster. Donald F. Figer Rochester Institute of Technology/STScI J. MacKenty, M. Robberto, K. Smith (STScI), F. Najarro (CSIC), R. Kudritzki (UH), A. Herrero (IAC). Main Points.
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Discovery of an Extraordinarily Massive Young Stellar Cluster Donald F. FigerRochester Institute of Technology/STScI J. MacKenty, M. Robberto, K. Smith (STScI), F. Najarro (CSIC), R. Kudritzki (UH), A. Herrero (IAC)
Main Points • Our team is announcing that we have found the richest cluster of red supergiants in the Galaxy. • We made this finding using 2MASS, IRMOS, and the Spitzer Space Telescope. • We identified 14 red supergiants using spectra. • The cluster is one of the most massive in Galaxy. • The cluster is near rare high energy objects. • The cluster is a hotbed of supernovae activity. • The research was sponsored by NASA LTSA.
Logic Flow of Discovery • Selected target from list of possible clusters. • Used 2MASS image to target stars for spectroscopic observations. • Obtained infrared spectra with IRMOS. • Obtained mid-infrared fluxes from Spitzer. • Compared data to well known red supergiants. • Discovered 14 red supergiants in cluster. • Associated high energy objects with cluster. • Inferred age, mass, and status of cluster.
Need for Infrared Observations Optically visible stars in blue.
Suspected Red Supergiants Infrared Brightness Infrared Color
Spectra Obtained with IRMOS Intensity Conclusion: Stars are Red Supergiants
Red supergiants are one thousand times larger than the Sun and one hundred times larger than a red giant. (a quarter mile across on this scale!)
Observation Theory Cluster Age Conclusion: Age~10 Myr Brightness
HESS TeV Source Near Cluster All High Energy TeV Sources in Sky
Most Massive Stars Project • Goal is to find the most massive stars in the Galaxy. • The sample includes hundreds of candidate stellar clusters. • The red supergiant cluster is the first target in the sample. • We will use IRMOS, Hubble, Spitzer, Chandra, VLA, and GTC to observe more candidates.
Conclusions • We found a new Galactic stellar cluster. • It contains three times as many red supergiants as any other Galactic cluster. • It is associated with rare high energy objects. • It likely had an initial mass of >20,000 M. • There are likely more similar clusters.