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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20120524T000000
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UID:iactalks-391
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/391
CREATED:2012-05-24T00:00:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:Distances to galaxies from the brightest stars in the Universe 
DESCRIPTION:Distances to galaxies from the brightest stars in the Universe 
 \nDr. Miguel Urbaneja\n\nMeasuring distances to galaxies and determining t
 heir chemical compositions are two fundamental activities in modern extrag
 alactic astronomy, in that they help characterizing the physical propertie
 s of their constituents and their evolutionary status. Ultimately, these m
 easurements lead to stronger constraints on the cosmological parameters of
  an expanding universe and the history of cosmic chemical enrichment. Both
  these questions can be tackled afresh with the quantitative analysis of t
 he absorption line spectra of individual massive and luminous, young B- an
 d A-type supergiant stars. A spectroscopic distance determination method, 
 the FGLR, can yield accurate distances up to several Mpc, extending to a l
 ocal volume where the results can be compared with those obtained from Cep
 heids and other distance indicators. Moreover, and this being a unique adv
 antage of the FGLR, reddening values and metallicities are simultaneously 
 determined for each individual stellar target. These stellar metallicities
  are very accurate and can be used to constrain the formation and evolutio
 n of galaxies and to assess and overcome the systematic uncertainties of H
  II region strong-line abundances through a galaxy-by-galaxy comparison. M
 oreover, stellar spectroscopy provides fundamental complementary abundance
  information for star forming galaxies on additional atomic species such a
 s iron-group elements. I will present recent results of our on-going effor
 ts to study individual blue supergiant stars in galaxies within and beyond
  the Local Group based on medium and low resolution optical spectra collec
 ted with ESO VLT and the Keck telescopes. The promising perspectives of fu
 ture work, based on the giant ground-based telescopes of the next generati
 on (E-ELT, TMT) are also discussed.
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