J/A+A/605/A54 ESO 435-02/ESO 435-016 ATCA HI images (Kim+, 2017)
HI properties and star formation history of a fly-by pair of blue compact dwarf
galaxies.
Kim J., Chung A., Wong O.I., Lee B., Sung E.-C., Staveley-Smith L.
<Astron. Astrophys. 605, A54 (2017)>
=2017A&A...605A..54K 2017A&A...605A..54K (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, peculiar ; Radio sources ; H I data
Keywords: galaxies: individual: ESO 435-020 -
galaxies: individual: ESO 435-016 - galaxies: interactions -
galaxies: ISM - galaxies: kinematics and dynamics -
galaxies: starburst
Abstract:
A fly-by interaction has been suggested to be one of the major
explanations for enhanced star formation in blue compact dwarf (BCD)
galaxies, yet no direct evidence for this scenario has been found to
date. In the HI Parkes all-sky survey (HIPASS), ESO 435-IG 020 and
ESO 435-G 016, a BCD pair were found in a common, extended gas
envelope of atomic hydrogen, providing an ideal case to test the
hypothesis that the starburst in BCDs can be indeed triggered by a
fly-by interaction. Using high-resolution data from the Australia
Telescope Compact Array (ATCA), we investigated HI properties and the
spectral energy distribution (SED) of the BCD pair to study their
interaction and star formation histories. The high-resolution HI data
of both BCDs reveal a number of peculiarities, which are suggestive of
tidal perturbation. Meanwhile, 40% of the HIPASS flux is not accounted
for in the ATCA observations with no HI gas bridge found between the
two BCDs. Intriguingly, in the residual of the HIPASS and the ATCA
data, ∼10% of the missing flux appears to be located between the two
BCDs. While the SED-based age of the most dominant young stellar
population is old enough to have originated from the interaction with
any neighbors (including the other of the two BCDs), the most recent
star formation activity traced by strong Hα emission in ESO
435-IG 020 and the shear motion of gas in ESO 435-G 016, suggest a
more recent or current tidal interaction. Based on these and the
residual emission between the HIPASS and the ATCA data, we propose an
interaction between the two BCDs as the origin of their recently
enhanced star formation activity. The shear motion on the gas disk,
potentially with re-accretion of the stripped gas, could be
responsible for the active star formation in this BCD pair.
Description:
The HI observations were conducted on March 27 and 28 2002 with the
ATCA in EW367 array configuration (project ID of C1024). The ATCA
primary beam is 33.1-arcmin at 1416MHz, which is comparable to the
angular distance between the pair of galaxies of ∼30.3-arcmin. With a
single pointing, the sensitivity at the locations of the galaxies
hence drops by a factor of ∼1.8, and therefore we had two extra
pointings centered on each galaxy in order to keep the desired
sensitivity toward the pair. The observing frequency was centered on
1416MHz with a total bandwidth of 8MHz, which is configured into 512
channels, yielding a channel width of 3.3km/s.
Objects:
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RA (2000) DE Designation(s)
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09 59 21.23 -28 08 00.0 ESO 435-020 = LEDA 28863
09 58 46.22 -28 37 18.9 ESO 435-016 = LEDA 28822
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 123 1 Information on fits datacube
datacube.fits 2880 392 ESO 435-016/ESO 435-020 ATCA HI data cube
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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- 21 I2 --- Nx Number of pixels along X-axis
23- 25 I3 --- Ny Number of pixels along Y-axis
27- 28 I2 --- Nz Number of slices
30- 39 A10 "date" Obs.Date Observation date
41- 47 F7.3 km/s bVel Lower value of velocity interval
49- 54 F6.1 km/s BVel Upper value of velocity interval
56- 62 F7.5 km/s dVel Velocity resolution
64- 67 I4 Kibyte size Size of FITS file
69- 81 A13 --- FileName Name of FITS file
83-123 A41 --- Title Title of the FITS file
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Acknowledgements:
Aeree Chung, achung(at)yonsei.ac.kr
(End) Patricia Vannier [CDS] 14-Sep-2017