J/A+A/705/A139 VESTIGE XIX line spectra and RVs of NGC 4569 tail (Sun+, 2026)
A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE). XIX.
The discovery of a spectacular 230 kpc Hα tail following NGC 4569 in the
Virgo cluster
Sun M., Le H., Epinat B., Boselli A., Luo R., Hosogi K., Pichette N.,
Forman W., Sarazin C., Fossati M., Chen H., Hensler G., Sarpa E.,
Amram P., Braine J., Cuillandre J.C., Gwyn S., Martocchia S.,
Vollmer B.
<Astron. Astrophys. 705, A139 (2026)>
=2026A&A...705A.139S 2026A&A...705A.139S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Positional data ; Galaxies, spectra ;
Spectroscopy ; Optical ; Radial velocities ; Line Profiles
Keywords: galaxies: clusters: general -
galaxies: clusters: intracluster medium - galaxies: evolution -
galaxies: ISM - galaxies: clusters: individual: Virgo -
galaxies: individual: NGC 4569
Abstract:
Galaxies fly inside galaxy clusters and ram pressure by the
intracluster medium (ICM) can remove a large amount of the
interstellar medium (ISM) from the galaxy, and deposit the gas in the
ICM. The ISM decoupled from the host galaxy leaves a long trail
following the moving galaxy. Such long trails track the galaxy motion
and can be detected with sensitive data in Hα.
We study the Hα tail trailing NGC 4569 in the Virgo cluster.
Methods. The initial discovery was made with the deep Hα imaging
data with CFHT, from the VESTIGE project. The follow-up spectroscopic
observations were made with APO/DIS, MMT/Binospec and CFHT/SITELLE.
Besides the known 80kpc Hα tail downstream of NGC 4569, the
deep Hα imaging data allow the Hα tail detected to at
least 230 kpc from the galaxy. More importantly, the Hα clumps
implied from the imaging data are confirmed with the spectroscopic
data. The Hα clumps show a smooth radial velocity gradient
across ∼1300km/s, eventually reaching the velocity of the cluster.
This discovery, for the first time, demonstrates the full deceleration
process of the stripped ISM. This discovery also showcases the
potential with wide-field Hα survey on galaxy clusters to
discover intracluster optical emission-line clouds originated from
cluster galaxies. These clouds provide kinematic tracers to the infall
history of cluster galaxies and the turbulence in the ICM. They are
also excellent multi-phase objects to study the classical cloud
crushing problem and other relevant important physical processes.
Description:
For VESTIGE survey, we provide velocity values of Hα clumps
shown in Figures 1 and 3. As explained in section Binospec data and
analysis, we conduct spectroscopic observations of emission-line
objects trailing NGC 4569 with the Binospec spectrograph on the MMT
telescope. The wavelength coverage varies across the field but is
typically ∼4900-7200Å, with a 0.62Å/pixel dispersion and ∼
2800 resolving power for 1'' slits. The Binospec data were reduced
with the Binospec pipeline and the 2D spectrum of each slit was
examined to identify the regions of interest for extraction also with
the help of the VESTIGE imaging data. We then used our own python code
to extract 1D spectra from the 2D spectra and fit spectra to obtain
barycentric velocities and line ratios (i.e results presented in
binospec.dat). The fit was done with five Gaussian functions with the
same velocity to model the Hα, [NII] and [SII] lines, plus
a continuum model. Next, we proceed to CFHT SITELLE iFTS data and
analysis to produce barycentric velocity of the tail (i.e results are
in sitelle.dat). We also compared the Binospec velocities with the
SITELLE velocities for 12 overlapping regions, all close to the
galaxy. Velocities are always consistent within the combined
uncertainties of both measurements.
Objects:
----------------------------------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------------------------------
12 36 49.80 +13 09 46.5 NGC 4569 = 1E 1234.2+1326
----------------------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
binospec.dat 50 94 Velocity values and line ratios for
94 Halpha clumps from the Binospec data
sitelle.dat 33 2145 Velocity values from the SITELLE data
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See also:
J/A+A/635/A135 : Galaxies around M87 (Kashibadze+, 2020)
J/A+A/587/A68 : Ionised gas images of NGC 4569 (Boselli+, 2016)
J/A+A/570/A69 : GALEX Ultraviolet Virgo Cluster Survey. IV. (Boselli+, 2014)
J/MNRAS/413/813 : ATLAS3D project. I. (Cappellari+, 2011)
J/ApJ/655/144 : ACS Virgo Cluster Survey. XIII. (Mei+, 2007)
Byte-by-byte Description of file: binospec.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.7 deg RAdeg Right ascension (J2000) (RA)
13- 22 F10.7 deg DEdeg Declination (J2000) (DEC)
24- 27 I4 km/s RV Barycentric velocity (VEL)
29- 30 I2 km/s e_RV Barycentric velocity 1-sigma error (VEL_E)
32- 35 F4.2 --- NII/Ha ? The NII at 6584Å to Hα emission line
ratio (Ratio1)
37- 40 F4.2 --- e_NII/Ha ? The 1-σ error of NII/Ha (Ratio1_E)
42- 45 F4.2 --- SII/Ha ? The SII at 6717Å and 6731Å to Halpha
emission line ratio (Ratio2)
47- 50 F4.2 --- e_SII/Ha ? The 1-σ error of SII/Ha (Ratio2_E)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: sitelle.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right ascension (J2000) (RA)
12- 19 F8.5 deg DEdeg Declination (J2000) (DEC)
21- 26 F6.1 km/s RV Barycentric velocity (VEL)
29- 33 F5.1 --- SNR Signal-to-Noise ratio of the Hα line
(SNR)
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Acknowledgements:
Ming Sun, ms0071(at)uah.edu
References:
Boselli et al., Paper I 2018A&A...614A..56B 2018A&A...614A..56B
Fossati et al., Paper II 2018A&A...614A..57F 2018A&A...614A..57F
Boselli et al., Paper III 2018A&A...615A.114B 2018A&A...615A.114B
Boselli et al., Paper IV 2018A&A...620A.164B 2018A&A...620A.164B
Boselli et al., Paper V 2019A&A...623A..52B 2019A&A...623A..52B
Boselli et al., Paper VI 2020A&A...634L...1B 2020A&A...634L...1B
Boselli et al., Paper VII 2020A&A...644A.161L 2020A&A...644A.161L
Volmer et al., Paper VIII 2021A&A...645A.121V 2021A&A...645A.121V
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Junais et al., Paper XIII 2022A&A...667A..76J 2022A&A...667A..76J, Cat. J/A+A/667/A76
Boselli et al., Paper XIV 2023A&A...669A..73B 2023A&A...669A..73B
Boselli et al., Paper XV 2023A&A...675A.123B 2023A&A...675A.123B
Morgan et al., Paper XVI 2024A&A...691A..20M 2024A&A...691A..20M
Boselli et al., Paper XVII 2025A&A...696A..78B 2025A&A...696A..78B
Martocchia et al., Paper XVIII 2025A&A...696A..79M 2025A&A...696A..79M
(End) Ming Sun [Univ. of Alabama], Luc Trabelsi [CDS] 12-Dec-2025