J/A+A/696/A22 Kinematics of gas and stars in NGC 7742 (Zamora+, 2025)
Physical properties of circumnuclear ionising clusters.
III. Kinematics of gas and stars in NGC 7742.
Zamora S., Diaz A.I., Terlevich R., Terlevich E., Amorin R
<Astron. Astrophys. 696, A22 (2025)>
=2025A&A...696A..22Z 2025A&A...696A..22Z (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; Spectroscopy ; Equivalent widths
Keywords: H II regions - galaxies: individual: NGC 7742 -
galaxies: star clusters: general - galaxies: star formation
Abstract:
In this third paper in a series, we study the kinematics of the
ionised gas and stars, and calculated the dynamical masses
of the circumnuclear star-forming regions in the ring of the face-on
spiral NGC 7742.
We have used high spectral resolution data from the MEGARA instrument
attached to the Gran Telescopio Canarias (GTC) to measure the
kinematical components of the nebular emission lines of selected HII
regions and the stellar velocity dispersions from the CaT absorption
lines that allow the derivation of the associated cluster virialized
masses.
The emission line profiles show two different kinematical components:
a narrow one with a velocity dispersion of ∼10km/s and a broad one
with a velocity dispersion similar to the values found for the stellar
absorption lines. The derived star cluster dynamical masses range from
2.5x106 to 10.0x107M☉.
The comparison of gas and stellar velocity dispersions suggests a
scenario where the clusters have formed simultaneously in a first star
formation episode with a fraction of the stellar evolution feedback
remaining trapped in the cluster, subject to the same gravitational
potential as the cluster stars. Between 0.15 and 7.07% of the total
dynamical mass of the cluster would have cooled down and formed a new,
younger, population of stars, responsible for the ionisation of the
gas currently observed.
Description:
In this third paper in the series, we analysed the kinematics of
gas and stars in the circumnuclear ring of NGC 7742 estimating the
dynamical masses of their CNSFRs from high spectral resolution data.
We extracted spectra for each region using the apertures selected from
Hα images. The analysis of the emission line profiles, show the
presence of two different kinematical components with the same radial
velocity.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 65 155 Emission line radial velocities
table4.dat 61 154 Emission line velocity dispersions
table5.dat 27 79 Equivalent widths of stellar absorption lines
of the observed CNSFRs
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Region Region ID (R1/R88)
5- 14 A10 --- Comp Component
16- 21 F6.2 km/s vHa Hα velocity
23- 27 F5.2 km/s e_vHa Hα velocity error
29- 34 F6.2 km/s v[NII] ?=- [NII] 6584Å line velocity
36- 40 F5.2 km/s e_v[NII] ?=- [NII] 6584Å line velocity error
42- 47 F6.2 km/s v[SII] ?=- [SII] 6717Å line velocity
49- 52 F4.2 km/s e_v[SII] ?=- [SII] 6717Å line velocity error
54- 59 F6.2 km/s v[SIII] ?=- [SIII] 9535Å line velocity
61- 65 F5.2 km/s e_v[SIII] ?=- [SIII] 9535Å line velocity error
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
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1- 3 A3 --- Region Region ID (R1/R88)
5- 13 A9 --- Comp Component
15- 20 F6.2 km/s sigmaHa Hα velocity dispersion
22- 26 F5.2 km/s e_sigmaHa Hα velocity dispersion error
28- 32 F5.2 km/s sigma[NII] ?=- [NII] 6584Å line velocity dispersion
34- 38 F5.2 km/s e_sigma[NII] ?=- [NII] 6584Å line velocity dispersion
error
40- 44 F5.2 km/s sigma[SII] ?=- [SII] 6717Å line velocity dispersion
46- 49 F4.2 km/s e_sigma[SII] ?=- [SII] 6717Å line velocity dispersion
error
51- 55 F5.2 km/s sigma[SIII] ?=- [SIII] 9535Å line velocity dispersion
57- 61 F5.2 km/s e_sigma[SIII] ?=- [SIII] 9535Å line velocity dispersion
error
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Region Region ID (R1/R88)
5- 9 F5.3 0.1nm EW(CaII) CaII (8542Å+8662Å+8498Å)
equivalent width
11- 15 F5.3 0.1nm e_EW(CaII) CaII (8542Å+8662Å+8498Å)
equivalent width error
17- 21 F5.3 0.1nm EW(MgI) MgI equivalent width
23- 27 F5.3 0.1nm e_EW(MgI) MgI equivalent width error
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Acknowledgements:
Sandra Zamora Arenal, szamo93(at)gmail.com
References:
Zamora & Diaz, Paper I 2023MNRAS.525.5767Z 2023MNRAS.525.5767Z
Zamora & Diaz, Paper II 2025A&A...696A..21Z 2025A&A...696A..21Z
(End) Patricia Vannier [CDS] 06-Mar-2025