J/A+A/701/A87 Nearby SF spirals in galaxy groups images (Saponara+, 2025)
MeerKAT radio continuum imaging of nearby star-forming spirals in the
NGC 6221, NGC 3256/3263, and NGC 2434 galaxy groups.
Saponara J., Koribalski B.S., English J., Humire P.K.
<Astron. Astrophys. 701, A87 (2025)>
=2025A&A...701A..87S 2025A&A...701A..87S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Galaxies, group ; Radio continuum
Keywords: galaxies: evolution - galaxies: groups: individual: NGC 6221 -
galaxies: groups: individual: NGC 3256/3263 -
galaxies: groups: individual: NGC 2434 - galaxies: star formation -
radio continuum: galaxies
Abstract:
We present high-resolution MeerKAT 1.3GHz radio continuum images of
star-forming spirals in the nearby galaxy groups around NGC 6221,
NGC3256/3263, and NGC 2434. This sample spans the evolutionary
timeline for galaxy groups, encompassing early, intermediate, and late
stages, respectively. The NGC 6221 group contains an interacting
galaxy pair with tidal debris, along with at least three dwarf
galaxies. In contrast, the NGC 3256/3263 group represents a loose
group consisting of several spiral as well as dwarf galaxies, while a
massive elliptical galaxy dominates the NGC 2434 group.
We study the star formation activity in all detected galaxies as it is
one of the dominant physical processes in their formation and
evolution, seeking evidence of environmental impact.
We use MeerKAT radio continuum data and archival WISE infrared data
to locate and measure the star formation rate in all group members. In
particular, we used polycyclic aromatic hydrocarbons (PAH) as tracers
of gas heated due to star formation activity. Furthermore, we create
in-band spectral index maps, providing insights into the underlying
physical processes associated with the detected star-forming regions.
For some galaxies, we also determine key stellar properties like age
and mass through SED fittings.
We found that galaxies are distributed differently in the WISE
colour-colour diagram depending on their evolutionary group stage, as
expected. Except for ESO 059-G012, the galaxies in our sample follow
the radio-W3PAH correlation. A possible scenario that explains the
ESO 059-G012 result is that the galaxy has already consumed the gas.
We also found evidence that the interaction among the spiral galaxies
NGC 3263, NGC 3256B, and NGC 3256C is causing the Vela Cloud complex
and that the galaxies NGC 6221 and NGC 3256 might host a
low-luminosity AGN, as was previously proposed in the literature.
Description:
Spectral lines and radio continuum observations of the three nearby
galaxy groups (project SCI-20210212-BK-01) were carried out during
2021 and 2022 with the MeerKAT radio interferometer located in the
Karoo desert of South Africa. We present the radio continuum data for
which we used a centre frequency of 1.3GHz and a bandwidth of 856MHz.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 111 20 List of fits images
fits/* . 20 Individual fits images or datacubes
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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- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 29 I2 --- Nz ? Number of slices for the datacubes
31- 51 A21 "datime" Obs.date Observation date
53- 59 F7.5 GHz Freq Observed frequency
61- 64 I4 Kibyte size Size of FITS file
66- 83 A18 --- FileName Name of FITS file, in subdirectory fits
85-111 A27 --- Title Title of the FITS file
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Acknowledgements:
Saponara Juliana, jsaponara(at)iar-conicet.gov.ar
(End) Patricia Vannier [CDS] 21-Jul-2025