Young stars in nearby early-type galaxies: SED fitting based on ultraviolet (UV) and optical imaging

Hyunjin Jeong, Sukyoung Yi, Martin Bureau, Roger L. Davies

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

Recent studies from the Galaxy Evolution Explore (GALEX) ultraviolet (UV) data have demonstrated that the recent star formation is more common in early-type galaxies (ETGs) than we used to believe. The UV is one order of magnitude more sensitive than the optical to the presence of young stellar populations. The near-ultraviolet (NUV) lights of ETGs, especially, are used to reveal their residual star formation history. Here we used the GALEX UV data of 34 nearby early-type galaxies from the SAURON sample, all of which have optical data from MDM Observatory. At least 15% of the galaxies in this sample show blue UV-optical colours suggesting recent star formation (Jeong et al. 2009). These NUV blue galaxies are generally low velocity dispersion systems and change the slopes of scaling relations (colour-magnitude relations and fundamental planes) and increase the scatters. To quantify the amount of recent star formation in our sample, we assume two bursts of star formation, allowing us to constrain the age and mass fraction of the young component pixel by pixel (Jeong et al. 2007). The pixel-by-pixel SED fitting based on UV and optical imaging reveals that the mass fraction of young (< 1 Gyr old) stars in ETGs varies between 1 and 3% in the nearby universe (Jeong et al. in prep.). We will compare our results with the prediction from the hierarchical merger paradigm to understand the mechanism of low-level recent star formation observed in early-type galaxies.

Original languageEnglish
Title of host publicationThe Spectral Energy Distribution of Galaxies
EditorsRichard J. Tuffs, Cristina C. Popescu
Pages240-243
Number of pages4
EditionS284
DOIs
Publication statusPublished - 2011 Sep 1

Publication series

NameProceedings of the International Astronomical Union
NumberS284
Volume7
ISSN (Print)1743-9213
ISSN (Electronic)1743-9221

Fingerprint

galaxies
stars
star formation
pixels
color
ultraviolet radiation
low speed
bursts
observatories
universe
histories
slopes
scaling
predictions

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics

Cite this

Jeong, H., Yi, S., Bureau, M., & Davies, R. L. (2011). Young stars in nearby early-type galaxies: SED fitting based on ultraviolet (UV) and optical imaging. In R. J. Tuffs, & C. C. Popescu (Eds.), The Spectral Energy Distribution of Galaxies (S284 ed., pp. 240-243). (Proceedings of the International Astronomical Union; Vol. 7, No. S284). https://doi.org/10.1017/S1743921312009155
Jeong, Hyunjin ; Yi, Sukyoung ; Bureau, Martin ; Davies, Roger L. / Young stars in nearby early-type galaxies : SED fitting based on ultraviolet (UV) and optical imaging. The Spectral Energy Distribution of Galaxies. editor / Richard J. Tuffs ; Cristina C. Popescu. S284. ed. 2011. pp. 240-243 (Proceedings of the International Astronomical Union; S284).
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abstract = "Recent studies from the Galaxy Evolution Explore (GALEX) ultraviolet (UV) data have demonstrated that the recent star formation is more common in early-type galaxies (ETGs) than we used to believe. The UV is one order of magnitude more sensitive than the optical to the presence of young stellar populations. The near-ultraviolet (NUV) lights of ETGs, especially, are used to reveal their residual star formation history. Here we used the GALEX UV data of 34 nearby early-type galaxies from the SAURON sample, all of which have optical data from MDM Observatory. At least 15{\%} of the galaxies in this sample show blue UV-optical colours suggesting recent star formation (Jeong et al. 2009). These NUV blue galaxies are generally low velocity dispersion systems and change the slopes of scaling relations (colour-magnitude relations and fundamental planes) and increase the scatters. To quantify the amount of recent star formation in our sample, we assume two bursts of star formation, allowing us to constrain the age and mass fraction of the young component pixel by pixel (Jeong et al. 2007). The pixel-by-pixel SED fitting based on UV and optical imaging reveals that the mass fraction of young (< 1 Gyr old) stars in ETGs varies between 1 and 3{\%} in the nearby universe (Jeong et al. in prep.). We will compare our results with the prediction from the hierarchical merger paradigm to understand the mechanism of low-level recent star formation observed in early-type galaxies.",
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Jeong, H, Yi, S, Bureau, M & Davies, RL 2011, Young stars in nearby early-type galaxies: SED fitting based on ultraviolet (UV) and optical imaging. in RJ Tuffs & CC Popescu (eds), The Spectral Energy Distribution of Galaxies. S284 edn, Proceedings of the International Astronomical Union, no. S284, vol. 7, pp. 240-243. https://doi.org/10.1017/S1743921312009155

Young stars in nearby early-type galaxies : SED fitting based on ultraviolet (UV) and optical imaging. / Jeong, Hyunjin; Yi, Sukyoung; Bureau, Martin; Davies, Roger L.

The Spectral Energy Distribution of Galaxies. ed. / Richard J. Tuffs; Cristina C. Popescu. S284. ed. 2011. p. 240-243 (Proceedings of the International Astronomical Union; Vol. 7, No. S284).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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Jeong H, Yi S, Bureau M, Davies RL. Young stars in nearby early-type galaxies: SED fitting based on ultraviolet (UV) and optical imaging. In Tuffs RJ, Popescu CC, editors, The Spectral Energy Distribution of Galaxies. S284 ed. 2011. p. 240-243. (Proceedings of the International Astronomical Union; S284). https://doi.org/10.1017/S1743921312009155