J/A+A/681/A100 Malin 1 MUSE images (Junais+, 2024)
MUSE observations of the giant low surface brightness galaxy Malin 1.
Numerous HII regions, star formation rate, metallicity, and dust attenuation.
Junais S., Weilbacher P.M., Epinat B., Boissier S., Galaz G., Johnston E.J.,
Puzia T.H., Amram P., Malek K.
<Astron. Astrophys. 681, A100 (2024)>
=2024A&A...681A.100J 2024A&A...681A.100J (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Photometry, H-alpha ; Abundances ;
Radio sources
Keywords: galaxies: individual: Malin 1 - galaxies: star formation -
galaxies: abundances - galaxies: ISM
Abstract:
Giant low-surface brightness (GLSB) galaxies are an extreme class of
objects with very faint and extended gas-rich disks. Malin 1 is the
largest GLSB galaxy known to date, but its formation is still poorly
understood.
We use VLT/MUSE IFU spectroscopic observations of Malin 1 to reveal,
for the first time, the presence of Hα emission distributed
across numerous regions along its disk, up to radial distances of
∼100kpc. We made an estimate of the dust attenuation using the Balmer
decrement and found that Malin 1 has a mean Hα attenuation of
0.36mag. We observe a steep decline in the star formation rate surface
density ({SIGMA}SFR) within the inner 20kpc, followed by a shallow
decline in the extended disk. Similarly, the gas phase metallicity we
estimated shows a steep gradient in the inner 20kpc, followed by a
flattening of the metallicity in the extended disk with a relatively
high value of ∼0.6Z☉. We found that the normalized abundance
gradient of the inner disk is similar to values found in normal
galaxies but with an extreme value in the extended disk. A comparison
of the star formation rate surface density and gas surface density
shows that, unlike normal disk galaxies or other LSBs, Malin 1
exhibits a very low star formation efficiency.
Owing to the detection of emission lines over a large part of the disk
of Malin 1, this work sheds light on the star formation processes in
this unique galaxy, highlighting its extended star-forming disk, dust
attenuation, almost flat metallicity distribution in the outer disk,
and exceptionally low star-formation efficiency. Our findings
contribute to a more detailed understanding of the formation of the
giant disk of Malin 1 and also constrain possible proposed scenarios
on the nature of GLSB galaxies in general.
Description:
Emission line maps of Malin 1 (Figure 2 and 3 of the paper) and the
estimated properties as given in Table A.1.
Objects:
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RA (2000) DE Designation(s)
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12 36 59.34 +14 19 49.1 Malin 1 = LEDA 42102
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 106 60 Properties of the Hα selected regions
in the extended disk of Malin 1
list.dat 106 8 List of fits maps
fits/* . 8 Individual fits maps
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See also:
J/A+A/593/A126 : Malin 1 images at 6 wavelengths (Boissier+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Region Region ID
4- 11 F8.4 deg RAdeg Right Ascension of region (J2000)
13- 19 F7.4 deg DEdeg Declination of region (J2000)
21- 29 F9.5 kpc Dist Distnace from the galaxy center
31- 35 F5.2 arcsec+2 Area Area of the region
37- 45 F9.6 10-20W/m2/arcsec2 Halpha Halpha surface brightness
47- 55 F9.7 10-20W/m2/arcsec2 e_Halpha Halpha surface brightness error
57- 63 F7.5 --- Ha/Hb ?=- Balmer ratio
65- 72 F8.6 --- e_Ha/Hb ?=- Balmer ratio error
74- 80 F7.5 --- N2 ?=- Metallicity N2 (12+logO/H)
82- 89 F8.6 --- e_N2 ?=- Metallicity (N2) error
91- 97 F7.5 --- O3N2 ?=- Metallicity O3N2(12+logO/H)
99-106 F8.6 --- e_O3N2 ?=- Metallicity (O3N2) error
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Galaxy name
9- 17 F9.5 deg RAdeg Right Ascension of center (J2000)
18- 26 F9.5 deg DEdeg Declination of center (J2000)
28- 30 F3.1 arcsec/pix scale Scale of the image
32- 34 I3 --- Nx Number of pixels along X-axis
36- 38 I3 --- Ny Number of pixels along Y-axis
40- 43 I4 Kibyte size Size of FITS file
45- 76 A32 --- FileName Name of FITS file, in subdirectory fits
78-106 A29 --- Title Title of the FITS file
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Acknowledgements:
Snc Junais, junais(at)ncbj.gov.pl
(End) Patricia Vannier [CDS] 03-Nov-2023