J/A+A/645/A111 NGC 4654 CO(2-1) data cube (Lizee+, 2021)
Gas compression and stellar feedback in the tidally interacting and ram-pressure
stripped Virgo spiral galaxy NGC 4654.
Lizee T., Vollmer B., Braine J., Nehlig F.
<Astron. Astrophys. 645, A111 (2021)>
=2021A&A...645A.111L 2021A&A...645A.111L (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Carbon monoxide
Keywords: galaxies: evolution - galaxies: interactions -
galaxies: star formation - galaxies: clusters: individual: NGC 4654
Abstract:
NGC 4654 is a Virgo galaxy seen almost face-on, which undergoes nearly
edge-on gas ram pressure stripping and a fly-by gravitational
interaction with another massive galaxy, NGC 4639. NGC 4654 shows a
strongly compressed gas region near the outer edge of the optical
disk, with HI surface densities (HSDR), exceeding the canonical value
of 10-15M☉/pc2. New IRAM 30m HERA CO(2-1) data of NGC 4654 are
used to study the physical conditions of the ISM. The CO-to-H2
conversion factor was estimated and found to be one to two times the
Galactic value with significant decrease in the ratio between the
molecular fraction and the total ISM pressure in the HSDR,
self-gravitating gas, a Toomre parameter below Q=1 and star-formation
efficiency 1.5-2 times higher. Analytical models were used to
reproduce radial profiles of the SFR and the atomic and molecular
surface densities. A Toomre parameter of Q∼0.8 combined with an
increase in the velocity dispersion of {DELTA}vdisp∼5km/s are
necessary conditions to simultaneously reproduce the gas surface
densities and the SFR. A dynamical model was used to reproduce the gas
distribution of NGC 4654. The comparison between the velocity
dispersion given by the moment 2 map and the intrinsic 3D velocity
dispersion from the model were used to discriminate between regions of
broader linewidths caused by a real increase in the velocity
dispersion and those caused by an unresolved velocity gradient only.
We found that the 5km/s increase in the intrinsic velocity dispersion
is compatible with observations. During a period of gas compression
through external interactions, the gas surface density is enhanced,
leading to an increased SFR and stellar feedback. Under the influence
of stellar feedback, the gas density increases only moderately. The
stellar feedback acts as a regulator of star-formation, increasing the
turbulent velocity within the region.
Description:
Reduced CO(2-1) data cube from IRAM single-dish 30m HERA observations.
Objects:
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RA (2000) DE Designation(s)
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12 43 56.638 +13 07 34.86 NGC 4654 = IC 3708
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 167 1 Information on fits datacube
fits/* . 1 Fits datacube
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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- 29 I3 --- Nz Number of slices
31- 42 E12.6 m/s bVRAD Lower value of VRAD interval
44- 54 E11.6 m/s BVRAD Upper value of VRAD interval
56- 62 F7.1 m/s dVRAD VRAD resolution
64- 68 I5 Kibyte size Size of FITS file
70- 88 A19 --- FileName Name of FITS file, in subdirectory fits
90-167 A78 --- Title Title of the FITS file
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Acknowledgements:
We would like to thank Francois Nehlig and Jonathan Braine for the
observational and data reduction work behind this data cube.
From Thomas Lizee, thomas.lizee(at)astro.unistra.fr
(End) Patricia Vannier CDS 13-Jan-2021