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Galaxy Evolution Explorer Ultraviolet Color-Magnitude Relations and Evidence of Recent Star Formation in Early-Type Galaxies

2005; IOP Publishing; Volume: 619; Issue: 1 Linguagem: Inglês

10.1086/422811

1538-4357

S. K. Yi, Sung-Chul Yoon, Sugata Kaviraj, J. M. Deharveng, R. Michael Rich, Samir Salim, A. Boselli, Y.-W. Lee, Chang H. Ree, Y.-J. Sohn, Soo‐Chang Rey, Jae Woo Lee, J. Rhee, L. Bianchi, Y.‐I. Byun, J. Donas, P. G. Friedman, T. M. Heckman, Patrick Jelinsky, B. F. Madore, Roger F. Malina, D. C. Martin, B. Milliard, Patrick Morrissey, Susan G. Neff, David Schiminovich, O. Siegmund, Todd Small, Alexander S. Szalay, M. J. Jee, S.-W. Kim, T. Barlow, K. Forster, B. Y. Welsh, Ted K. Wyder,

Stellar, planetary, and galactic studies

We have used the Galaxy Evolution Explorer UV photometric data to construct a first near-UV (NUV) color-magnitude relation (CMR) for the galaxies preclassified as early-type by Sloan Digital Sky Survey studies. The NUV CMR is a powerful tool for tracking the recent star formation history in early-type galaxies, owing to its high sensitivity to the presence of young stellar populations. Our NUV CMR for UV-weak galaxies shows a well-defined slope and thus will be useful for interpreting the rest-frame NUV data of distant galaxies and studying their star formation history. Compared to optical CMRs, the NUV CMR shows a substantially larger scatter, which we interpret as evidence of recent star formation activities. Roughly 15% of the recent epoch (z < 0.13) bright [M(r) < -22] early-type galaxies show a sign of recent (≲1 Gyr) star formation at the 1%-2% level (lower limit) in mass compared to the total stellar mass. This implies that low-level residual star formation was common during the last few billion years even in bright early-type galaxies.