J/MNRAS/509/550 Recent star formation galaxies sample (Jeong+, 2022)
Early-type galaxies with recent star formation have low metallicities.
Evidence for star formation triggered by external processes?
Jeong H., Oh K., Joo S.-J., Yi S.K.
<Mon. Not. R. Astron. Soc., 509, 550-558>
=2022MNRAS.509..550J 2022MNRAS.509..550J (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, optical ; Photometry, ultraviolet ; Redshifts ;
Spectroscopy
Keywords: galaxies: abundances - galaxies: elliptical and lenticular, cD -
galaxies: evolution - galaxies: stellar content
Abstract:
On the basis of the Galaxy Evolution Explore (GALEX) ultraviolet (UV)
data, many studies have demonstrated that recent star formation (RSF)
is common in early-type galaxies. In particular, near-ultraviolet
(NUV) light is used to investigate star formation activity in
early-type galaxies, owing to its high sensitivity to the presence of
young stars. This study characterized the stellar population
properties of luminous early-type galaxies (Mr≤-20.65mag) in the
redshift range 0.005≥z≤0.09 on the basis of the Sloan Digital Sky
Survey (SDSS) data. Initially, the most frequently used criterion of
NUV-r≤5.4 was applied to identify early-type galaxies with RSF, and
19 per cent (172/913) of the sample galaxies met this criterion, in
agreement with previous studies. A more robust sample of galaxies with
RSF along with a stricter criterion (70 galaxies with NUV-r≤5.0) were
then used for further analysis, and consequently 7.7 per cent (70/913;
lower limit of the RSF fraction) of the sample galaxies were
classified as early-type galaxies with RSF. These galaxies tended to
exhibit higher Hβ absorption-line strengths and stronger emission
lines than quiescent (QST, NUVr>5.4) early-type galaxies. The most
prominent feature of early-type galaxies with RSF identified in this
study was that they were more metal-poor than QST galaxies owing to
metal-poor stellar populations that were possibly formed from
materials accreted from gas-rich satellites during (minor) mergers or
interactions. The results strongly indicate that the observed RSF in
the sample galaxies at the present epoch is mainly driven by external
processes (i.e. mergers or interactions).
Description:
We selected all SDSS DR7 galaxies with spectra in the redshift range
0.005≤z≤0.09 and applied an absolute r-band magnitude cut-off of
∼20.65 to obtain a volume-limited sample.
Table 2 provide a catalogue of the recent star formation (RSF)
galaxies considered in this study.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 90 70 Properties of our recent star formation (RSF)
early-type galaxies
--------------------------------------------------------------------------------
See also:
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 I18 --- objID SDSS object ID
20- 29 F10.6 deg RAdeg Right ascension (J2000)
31- 40 F10.6 deg DEdeg Declination (J2000)
42- 47 F6.4 --- z Redshift
49- 54 F6.2 mag rMAG Absolute r magnitude
56- 59 F4.2 mag u-r u-r colour index
61- 64 F4.2 mag FUV-r FUV-r colour index
66- 69 F4.2 mag NUV-r NUV-r colour index
71- 74 F4.2 0.1nm Hb Hβ index
76- 79 F4.2 [-] [MgFe]' Metallicity Index [MgFe]' (1)
81- 84 F4.1 Gyr Age Age
86- 90 F5.2 [-] [Z/H] Abundance [Z/H]
--------------------------------------------------------------------------------
Note (1): [MgFe]' = SQRT[Mgb(0.72xFe5270+0.28xFe5335)],
Thomas et al., 2003MNRAS.339..897T 2003MNRAS.339..897T
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 14-Aug-2024