J/AJ/155/234 Star formation rate distribution in NGC 1232 (de Souza+, 2018)
Star formation rate distribution in the galaxy NGC 1232.
de Souza A.A., Martins L.P., Rodriguez-Ardila A., Fraga L.
<Astron. J., 155, 234 (2018)>
=2018AJ....155..234D 2018AJ....155..234D (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, optical ; Star Forming Region ; Photometry, H-alpha ;
H II regions
Keywords: galaxies: individual (NGC 1232) - galaxies: star formation -
H II regions
Abstract:
NGC 1232 is a face-on spiral galaxy and a great laboratory for the
study of star formation due to its proximity. We obtained high spatial
resolution Hα images of this galaxy, with adaptive optics, using
the SAM instrument at the SOAR telescope, and used these images to study
its H II regions. These observations allowed us to produce the most
complete H II region catalog for it to date, with a total of 976 sources.
This doubles the number of H II regions previously found for this object.
We used these data to construct the H II luminosity function, and obtained
a power-law index lower than the typical values found for Sc galaxies.
This shallower slope is related to the presence of a significant number
of high-luminosity H II regions (log L>39 dex). We also constructed
the size distribution function, verifying that, as for most galaxies,
NGC 1232 follows an exponential law. We also used the Hα luminosity
to calculate the star formation rate. An extremely interesting fact about
this galaxy is that X-ray diffuse observations suggest that NGC 1232
recently suffered a collision with a dwarf galaxy. We found an absence of
star formation around the region where the X-ray emission is more intense,
which we interpret as a star formation quenching due to the collision.
Along with that, we found an excess of star-forming regions in the
northeast part of the galaxy, where the X-ray emission is less intense.
Description:
NGC 1232 was observed on the night of 2014 January 23 (Program
SO2013B-021), with the filters g', r', and Hα. The observations were
carried out with the SOAR telescope using the SOAR Adaptive Module (SAM),
an instrument with an installed laser-assisted adaptive optics (AO) system
(Fraga et al. 2013, J/AJ/145/165). By selectively compensating for
low-altitude turbulence, AO improves resolution at visible wavelengths.
The instrument contains a 4kx4k pixels CCD sensor that spans a square field
of 3'. The natural seeing in the V band during the observations was 0.8".
With AO the V-band seeing improved to 0.55". In Hα, the seeing was
0.5" and in the g' band, 0.66". Three individual on-source integrations
were carried out for each filter, of 240 s each for g' and r' and 600 s for
Hα. The standard star Hiltner 600 was also observed in the three
filters for flux calibration purposes.
Objects:
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RA (ICRS) DE Designation(s)
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03 09 45.51 -20 34 45.5 NGC 1232 = LEDA 11819
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 81 976 Data from sources detected in galaxy NGC 1232,
in order of luminosity
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See also:
J/A+A/441/981 : HII regions in 5 spiral galaxies (Bresolin+, 2005)
J/A+A/542/A39 : NIR photometry in 10 nearby spiral galaxies (Grosboel+, 2012)
J/AJ/145/165 : BVRI photometry in NGC 6496 (Fraga+, 2013)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/976] Sequential running number of source
5- 6 I2 h RAh Hour of Right Ascension (J2000)
8- 9 I2 min RAm Minute of Right Ascension (J2000)
11- 15 F5.2 s RAs Second of Right Ascension (J2000)
17- 17 A1 --- DE- Sign of the Declination (J2000)
18- 19 I2 deg DEd Degree of Declination (J2000)
21- 22 I2 arcmin DEm Arcminute of Declination (J2000)
24- 28 F5.2 arcsec DEs Arcsecond of Declination (J2000)
30- 37 F8.2 10-20W/m2 FHa [1.97/16220.5] Hα line flux
(in 10-17 erg/s/cm2)
39- 42 F4.2 10-20W/m2 e_FHa [0.25/7.99] Uncertainty in FHa
(in 10-17 erg/s/cm2)
44- 52 E9.3 Msun/yr SFR [5e-06/0.040332] Star formation rate
54- 61 E8.3 Msun/yr e_SFR [1e-06/0.00484] Uncertainty in SFR
63- 72 F10.5 pix2 Area [7/9670] SEXTRACTOR area
74- 81 E8.3 10-7W LHa [9.26e+35/7.61e+39] Hα luminosity
(in erg/s)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 14-Dec-2018