J/A+A/555/L4 Inner rings in disc galaxies from UV + Hα (Comeron, 2013)
Inner rings in disc galaxies: dead or alive.
Comeron S.
<Astron. Astrophys. 555, L4 (2013)>
=2013A&A...555L...4C 2013A&A...555L...4C
ADC_Keywords: Galaxies, nearby ; Galaxies, ring
Keywords: galaxies: evolution - galaxies: kinematics and dynamics -
galaxies: spiral - galaxies: statistics
Abstract:
In this Letter, I distinguish "passive" inner rings to be those with
no current star formation, as distinct from "active" inner rings
which have undergone recent star formation. I built a sample of nearby
galaxies with inner rings observed in the near- and mid-infrared by
the NIRS0S and the S4G surveys. I used archival far-ultraviolet (FUV)
and Hα imaging of 319 galaxies to diagnose whether their inner
rings are passive or active. I found that passive rings are found only
in early-type disc galaxies (-3≤T≤2). In this range of stages,
21±3% and 28±5% of rings are passive according to the FUV and
Hα indicators, respectively. A ring which is passive according to
FUV is always passive according to Hα, but the reverse is not
always true. Ring-lenses form 30-40% of passive rings, which is four
times more than the fraction of ring-lenses found in active rings in
the stage range -3≤T≤2. This is consistent with both a resonance and
a manifold origin for the rings because both models predict purely
stellar rings to be wider than their star-forming counterparts. In the
case of resonance rings, the widening may be at least partly due to
the dissolution of rings. If most inner rings have a resonance origin,
I estimate 200Myr to be a lower bound for their dissolution
time-scale. This time-scale is on the order of one orbital period at
the radius of inner rings.
Description:
Detection status of the inner rings in the sample according to the FUV
and Hα indicators. Other information includes the ring type, the
galaxy stage and family and the GALEX survey from which the FUV images
were obtained.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 46 319 Properties of the inner ring host galaxies and
detection status of the inner rings according
to the FUV and Hα indicators
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See also:
http://galex.stsci.edu/GR6/ : GALEX CR6/7 data release
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Galaxy name
12- 15 A4 --- Family Galaxy family to its bar classification (1)
17- 18 I2 --- Stage [-3/9] Galaxy stage T (1)
22- 28 A7 --- Kind [rsl'_, ] Inner ring kind (1)
30- 36 A7 --- FUV [AP?, ] Inner ring detection status
according to FUV (2)
38- 40 A3 --- GALEX GALEX survey of the image used for the FUV
detection (3)
44- 46 A3 --- Halpha [AP?, ] Inner ring detection status
according to Hα (2)
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Note (1): From NIRSOS (Laurikainen et al., 2011MNRAS.418.1452L 2011MNRAS.418.1452L) and
Buta et al. (2013 in preparation).
* Families: SA, SB, SAB, SAB_, or S_AB (the underscore emphasizes the
more likely family)
* Kind: presence (r), absence (s) or transition (rs) of inner rings,
and of lenses (l); the underscore emphasizes the more likely kind.
Note (2): "A" stands for active inner rings and "P" for passive inner rings.
Uncertain statuses are indicated with a "?".
Note (3): Galex survey as follows:
AIS = GALEX All-Sky Imaging Survey, which consists of ∼100s exposures and
can detect point sources down to µAB∼20mag/arcsec2.
CAI = Calibration Imaging
DIS = Deep Imaging Survey (30ks exposure)
GII = Through year 2009 the GALEX mission committed about 1/3 of its
observing program to carrying out observations for a Guest
Investigator (GI) program. This Program is now chiefly of historical
interest, except that the observations are currently being
reprocessed and posted under the name of the "GII Survey".
MIS = Medium Imaging Survey (1.5ks exposure)
NGS = Nearby Galaxy Survey (1.5ks exposure)
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Acknowledgements:
Sebastien Comeron, seb.comeron(at)gmail.com
(End) S. Comeron [Univ. of Oulu, Finland], P. Vannier [CDS] 19-Jun-2013