Recent star formation in nearby galaxies from GALEX imaging:M101 and M51

Luciana Bianchi (1) , David Thilker (1) , D. Burgarella (2) , P. Friedman (3) , C. Hoopes (1) , Samuel Boissier (4) , Armando Gil de Paz , T. Barlow (3) , Y. -I. Byun (5) , J. Donas (2) , K. Forster (3) , T. Heckman (1) , P. Jelinsky (6) , Y.-W. Lee (5) , B. Madore , R. Malina (2) , C. Martin (3) , B. Milliard (2) , P. Morrissey (3) , M. Rich (7) , David Schiminovich (3) , O. Siegmund (6) , Todd Small , A. Szalay , B. Welsh (6) , T. Wyder (3)

1 Department of Physics and Astronomy [Baltimore]
2 LAM - Laboratoire d'Astrophysique de Marseille
3 CALTECH - California Institute of Technology
4 Observatories [Carnegie Institution]
5 Center for Space Astrophysics [Seoul]
6 SSL - Space Sciences Laboratory [Berkeley]
7 Department of Physics and Astronomy [UCLA Los Angeles]

The GALEX (Galaxy Evolution Explorer) Nearby Galaxies Survey is providing deep far-UV and near-UV imaging for a representative sample of galaxies in the local universe. We present early results for M51 and M101, from GALEX UV imaging and SDSS optical data in five bands. The multi-band photometry of compact stellar complexes in M101 is compared to population synthesis models, to derive ages, reddening, reddening-corrected luminosities and current/initial masses. The GALEX UV photometry provides a complete census of young compact complexes on a approximately 160pc scale. A galactocentric gradient of the far-UV - near-UV color indicates younger stellar populations towards the outer parts of the galaxy disks, the effect being more pronounced in M101 than in M51.

Mots clés: galaxies: individual (M51; M101); galaxies: star clusters; ultraviolet: galaxies

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]

Luciana Bianchi, David Thilker, D. Burgarella, P. Friedman, C. Hoopes, et al.. Recent star formation in nearby galaxies from GALEX imaging:M101 and M51. The Astrophysical journal letters, 2005, 619, pp.L71-L74. ⟨hal-00012638⟩