Publication:
NGC 404: a rejuvenated lenticular galaxy on a Merger-induced, blueward excursion into the Green Valley

Research Projects
Organizational Units
Journal Issue
Abstract
We have discovered recent star formation in the outermost portion ((1-4) × R_25) of the nearby lenticular (S0) galaxy NGC 404 using Galaxy Evolution Explorer UV imaging. FUV-bright sources are strongly concentrated within the galaxy's H I ring (formed by a merger event according to del Río et al.), even though the average gas density is dynamically subcritical. Archival Hubble Space Telescope imaging reveals resolved upper main-sequence stars and conclusively demonstrates that the UV light originates from recent star formation activity. We present FUV, NUV radial surface brightness profiles, and integrated magnitudes for NGC 404. Within the ring, the average star formation rate (SFR) surface density (Σ_SFR) is ~2.2 × 10^–5 M_☉ yr^–1 kpc–2. Of the total FUV flux, 70% comes from the H I ring which is forming stars at a rate of 2.5 × 10^–3 M_☉ yr^–1. The gas consumption timescale, assuming a constant SFR and no gas recycling, is several times the age of the universe. In the context of the UV-optical galaxy color-magnitude diagram, the presence of the star-forming H I ring places NGC 404 in the green valley separating the red and blue sequences. The rejuvenated lenticular galaxy has experienced a merger-induced, disk-building excursion away from the red sequence toward bluer colors, where it may evolve quiescently or (if appropriately triggered) experience a burst capable of placing it on the blue/star-forming sequence for up to ~1 Gyr. The green valley galaxy population is heterogeneous, with most systems transitioning from blue to red but others evolving in the opposite sense due to acquisition of fresh gas through various channels.
Description
© 2010. The American Astronomical Society. GALEX is a NASA Small Explorer, launched in 2003 April. We gratefully acknowledge NASA's support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the Centre National d'Etudes Spatiales of France and the Korean Ministry of Science and Technology. This research has made use of the NASA/IPAC Extragalactic Database (NED). We acknowledge the usage of the HyperLeda database (http://leda.univ-lyon1.fr). The Digitized Sky Surveys were produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166. Some images presented in this Letter were obtained from the Multimission Archive at the Space Telescope Science Institute (MAST).
Unesco subjects
Keywords
Citation
Baldry, I. K., Glazebrook, K., Brinkmann, J., Ivezić, Ž., Lupton, R. H., Nichol, R. C., & Szalay, A. S. 2004, ApJ, 600, 681 Bell, E. F., et al. 2004, ApJ, 608, 752 Boissier, S., et al. 2007, ApJS, 173, 524 Calzetti, D., et al. 2005, ApJ, 633, 871 Cardelli, J. A., Clayton, G. C., & Mathis, J. S. 1989, ApJ, 345, 245 Cortese, L., & Hughes, T. M. 2009, MNRAS, 400, 1225 Dalcanton, J., et al. 2009, ApJS, 183, 67 Dale, D. A., et al. 2009, ApJ, 703, 517 del Río, M. S., Brinks, E., & Cepa, J. 2004, AJ, 128, 89 Donas, J., et al. 2007, ApJS, 173, 597 Donovan, J. L., et al. 2009, AJ, 137, 5037 Faber, S. M., et al. 2007, ApJ, 665, 265 Gil de Paz, A., et al. 2007, ApJ, 661, 115 Haynes, M. P., & Giovanelli, R. 1984, AJ, 89, 758 Kannappan, S. J., Guie, J. M., & Baker, A. J. 2009, AJ, 138, 579 Karachentsev, I. D., & Makarov, D. I. 1999, in IAU Symp. 186, Galaxy Interactions at Low and High Redshift, ed. J. E. Barnes & D. B. Sanders (Berlin: Springer), 109 Karachentsev, I. D., et al. 2002, A&A, 389, 812 Kaviraj, S., et al. 2007, ApJS, 173, 619 Kennicutt, R. C., Jr. 1998, ApJ, 498, 541 Krumholz, M. R., McKee, C. F., & Tumlinson, J. 2009, ApJ, 699, 850 Lee, J. C., et al. 2009, ApJ, 706, 599 Leitherer, C., et al. 1999, ApJS, 123, 3 Maoz, D., Filippenko, A. V., Ho, L. C., Rix, H.-W., Bahcall, J. N., Schneider, D. P., & Macchetto, F. D. 1995, ApJ, 440, 91 Maoz, D., Koratkar, A., Shields, J. C., Ho, L. C., Filippenko, A. V., & Sternberg, A. 1998, AJ, 116, 55 Marigo, P., Girardi, L., Bressan, A., Groenewegen, M. A. T., Silva, L., & Granato, G. L. 2008, A&A, 482, 883 Martin, D. C., et al. 2007, ApJS, 173, 342 (M07) Morganti, R., et al. 2008, in AIP Conf. Proc. 1035, The Evolution of Galaxies Through the Neutral Hydrogen Window, ed. R. Minchin & E. Momjian (Melville, NY: AIP), 129 Morrissey, P., et al. 2007, ApJS, 173, 682 Ohl, R. G., et al. 1998, ApJ, 505, L11 Oosterloo, T. A., Morganti, R., Sadler, E. M., van der Hulst, T., & Serra, P. 2007, A&A, 465, 787 Plana, H., Boulesteix, J., Amram, P., Carignan, C., & Mendes de Oliveira, C. 1998, A&AS, 128, 75 Prescott, M. K. M., et al. 2007, ApJ, 668, 182 Rich, R. M., & Salim, S. 2009, BAAS, 41, 252 Sage, L. J. 1990, A&A, 239, 125 Salim, S., et al. 2007, ApJS, 173, 267 Sandage, A., & Visvanathan, N. 1978, ApJ, 225, 742 Schawinski, K., et al. 2007, ApJS, 173, 512 Schawinski, K., et al. 2009, MNRAS, 396, 818 Schiminovich, D., et al. 2007, ApJS, 173, 315 Schlegel, D. J., Finkbeiner, D. P., & Davis, M. 1998, ApJ, 500, 525 Serra, P., Trager, S. C., Oosterloo, T. A., & Morganti, R. 2008, A&A, 483, 57 Strateva, I., et al. 2001, AJ, 122, 1861 Thilker, D. A., et al. 2007a, ApJS, 173, 538 Thilker, D. A., et al. 2007b, ApJS, 173, 572 Tikhonov, N. A., Galazutdinova, O. A., & Aparicio, A. 2003, A&A, 401, 863 Tonry, J. L., Dressler, A., Blakeslee, J. P., Ajhar, E. A., Fletcher, A. B., Luppino, G. A., Metzger, M. R., & Moore, C. B. 2001, ApJ, 546, 681 Trager, S. C., Faber, S. M., Worthey, G., & González, J. J. 2000, AJ, 120, 165 van der Hulst, J. M., van Albada, T. S., & Sancisi, R. 2001, in ASP Conf. Proc. 240, Gas and Galaxy Evolution, ed. J. E. Hibbard, M. Rupen, & J. H. van Gorkom (San Francisco, CA: ASP), 451 Wiklind, T., & Henkel, C. 1990, A&A, 227, 394 Wyder, T. K., et al. 2007, ApJS, 173, 293 (W07) Wyder, T. K., et al. 2009, ApJ, 696, 1834 Yi, S. K., et al. 2005, ApJ, 619, L111
Collections