J/A+A/672/A55 Deep VLA HI observations of NGC 2403 (Veronese+, 2023)
Extended neutral hydrogen filamentary network in NGC 2403.
Veronese S., de Blok W.J.G., Walter F.
<Astron. Astrophys. 672, A55 (2023)>
=2023A&A...672A..55V 2023A&A...672A..55V (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; H I data ; Galaxies, nearby
Keywords: galaxies: evolution - galaxies: interactions -
techniques: interferometric - radio lines: galaxies
Abstract:
We present new neutral hydrogen (HI) observations of the nearby galaxy
NGC 2403 to determine the nature of a low-column density cloud that
was detected earlier by the Green Bank Telescope. We find that this
cloud is the tip of a complex of filaments of extraplanar gas that is
coincident with the thin disk. The total HH mass of the complex is
2x107 solar masses or 0.6% of the total HI mass of the galaxy. The
main structure, previously referred to as the 8-kpc filament, is now
seen to be even more extended, along a 20kpc stream. The kinematics
and morphological properties of the filaments are unlikely to be the
result of outflows related to galactic fountains. It is more likely
that the 20kpc filament is related to a recent galaxy interaction. In
this context, a ∼50kpc long stellar stream has been recently detected
connecting NGC 2403 with the nearby dwarf satellite DDO 44.
Intriguingly, the southern tip of this stream overlaps with that of
20kpc HI filament. We conclude that the HI anomalies in NGC 2403 are
the result of a recent (∼2Gyr) interaction with DDO 44 leading to the
observed filamentary complex.
Description:
We present the reduced neutral hydrogen (HI) datacube obtained from
the combination of unpublished Very Large Array observations (Project
ID: 19B-081) with archival data (Fraternali et al.
(2001ApJ...562L..47F 2001ApJ...562L..47F), Walter et al. (2008AJ....136.2563W 2008AJ....136.2563W, Cat.
J/AJ/136/2563) of the nearby galaxy NGC 2403. The data reduction was
carried out with the software CASA v5.8.0 and the cube was created
with tclean. We applied a robustness parameter of 0.5 and a tapering
of 48-arcsec. The channel maps have 400x400-pixels with a 9-arcsec
per-pixel resolution. We chose the channel width to be 5.3km/s,
obtaining 102 channels. tclean was run in the auto-multithresh masking
mode with a noise threshold of 4xsigma. Inside the masked region the
data are smoothed by a factor of 1.5 and cleaned until the stopping
threshold of 0.5xsigma. The datacube is not primary-beam corrected.
The primary beam cube is also provided.
Objects:
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RA (2000) DE Designation(s)
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07 36 51.33 +65 36 09.6 NGC 2403 = UGC 3918
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 176 2 List of fits datacubes
fits/* . 2 Individual fits 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- 30 I3 --- Nz Number of pixels along Z-axis
32- 57 A26 "datime" Obs.date Observation date
59- 65 I7 m/s bVOPT Lower value of Vopt interval
67- 72 I6 m/s BVOPT Upper value of Vopt interval
74- 80 F7.2 m/s dVOPT Vopt resolution
82- 86 I5 Kibyte size Size of FITS file
88-120 A33 --- FileName Name of FITS file, in subdirectory fits
122-176 A55 --- Title Title of the FITS file
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Acknowledgements:
Simone Veronese, veronese(at)astron.nl
(End) Patricia Vannier [CDS] 01-Feb-2023