Star formation and figure rotation in the early-type galaxy NGC 2974

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

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

We present Galaxy Evolution Explorer (GALEX) far-ultraviolet (FUV) and near-ultraviolet (NUV) imaging of the nearby early-type galaxy NGC 2974, along with complementary ground-based optical imaging. In the ultraviolet, the galaxy reveals a central spheroid-like component and a newly discovered complete outer ring of radius 6.2 kpc, with suggestions of another partial ring at an even larger radius. Blue FUV-NUV and UV-optical colours are observed in the centre of the galaxy and from the outer ring outwards, suggesting young stellar populations (≲1 Gyr) and recent star formation in both locations. This is supported by a simple stellar population model which assumes two bursts of star formation, allowing us to constrain the age, mass fraction and surface mass density of the young component pixel by pixel. Overall, the mass fraction of the young component appears to be just under 1 per cent (lower limit, uncorrected for dust extinction). The additional presence of a nuclear and an inner ring (radii 1.4 and 2.9 kpc, respectively), as traced by [O III] emission, suggests ring formation through resonances. All three rings are consistent with a single pattern speed of 78 ± 6 km s-1 kpc-1, typical of S0 galaxies and only marginally slower than expected for a fast bar if traced by a small observed surface brightness plateau. This thus suggests that star formation and morphological evolution in NGC 2974 at the present epoch are primarily driven by a rotating asymmetry (probably a large-scale bar), despite the standard classification of NGC 2974 as an E4 elliptical.

Original languageEnglish
Pages (from-to)1021-1032
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Volume376
Issue number3
DOIs
Publication statusPublished - 2007 Apr 1

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star formation
galaxies
rings
pixel
young population
radii
asymmetry
extinction
pixels
plateau
dust
spheroids
suggestion
plateaus
bursts
brightness
time measurement
color
young
speed

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Jeong, Hyunjin ; Bureau, Martin ; Yi, Sukyoung ; Krajnović, Davor ; Davies, Roger L. / Star formation and figure rotation in the early-type galaxy NGC 2974. In: Monthly Notices of the Royal Astronomical Society. 2007 ; Vol. 376, No. 3. pp. 1021-1032.
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Star formation and figure rotation in the early-type galaxy NGC 2974. / Jeong, Hyunjin; Bureau, Martin; Yi, Sukyoung; Krajnović, Davor; Davies, Roger L.

In: Monthly Notices of the Royal Astronomical Society, Vol. 376, No. 3, 01.04.2007, p. 1021-1032.

Research output: Contribution to journalArticle

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T1 - Star formation and figure rotation in the early-type galaxy NGC 2974

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