discovery of an extraordinarily massive young stellar cluster donald f. figer rochester institute of...
Post on 19-Dec-2015
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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
1. Selected target from list of possible clusters.2. Used 2MASS image to target stars for
spectroscopic observations.3. Obtained infrared spectra with IRMOS.4. Obtained mid-infrared fluxes from Spitzer.5. Compared data to well known red supergiants.6. Discovered 14 red supergiants in cluster.7. Associated high energy objects with cluster.8. Inferred age, mass, and status of cluster.
Location in Galaxy
Need for Infrared Observations
Optically visible stars in blue.
Suspected Red Supergiants
Infr
ared
Brig
htne
ss
Infrared Color
Spectra Obtained with IRMOSIn
ten
sity
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!)
Cluster Age
Conclusion:Age~10 Myr
Theory
Observation
Brig
htne
ss
Cluster Mass
Supernovae Rate
5.8m+3.6m+20cm
HESS TeV Source Near Cluster
All High Energy TeV Sources in Sky
High Energy Objects
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.