2022A&A...657L..10Y

Query : 2022A&A...657L..10Y

2022A&A...657L..10Y - Astronomy and Astrophysics, volume 657, L10-10 (2022/1-1)

Hidden in plain sight: UVIT and MUSE discovery of a large, diffuse star-forming galaxy.

YADAV J., DAS M., BARWAY S. and COMBES F.

Abstract (from CDS):

We report the discovery of a nearby large, diffuse galaxy that shows star formation using Ultra Violet Imaging Telescope (UVIT) far-UV observations and archival optical data from Multi-Unit Spectroscopic Explorer (MUSE), Dark Energy Camera Legacy Survey, and InfraRed Survey Facility near-infrared observations. The galaxy was not detected earlier due to its superposition with the background galaxy NGC 6902A. They were together mistakenly classified as an interacting system. NGC 6902A is at a redshift of 0.05554, but MUSE observations indicate that the interacting tail is a separate star-forming foreground galaxy at a redshift of 0.00980. We refer to the new galaxy as UVIT J202258.73-441623.8 (UVIT J2022). The near-infrared observations show that UVIT J2022 has a stellar mass of 8.7 x 108 M☉. Its inner disk (R < 4 kpc) shows UV and Hα emission from ongoing massive star formation. The rest of the disk is extremely low in luminosity, has a low stellar surface density, and extends out to a radius of R ∼ 9 kpc. The velocity and metallicity distribution maps and the star formation history indicate that UVIT J2022 has undergone three bursts of star formation. The latest episode is ongoing, which is supported by the presence of widespread Hα and UV emission in its inner disk. The galaxy also shows patchy spiral arms in the far UV, and there is a metallicity enhancement along a bar-like feature. UVIT J2022 is thus a unique example of triggered star formation in a diffuse galaxy resulting in the growth of its inner stellar disk. Our study raises the intriguing possibilities that (i) there could be similar diffuse galaxies that have been mistakenly interpreted as interacting galaxies due to their superposition, and (ii) UV or Hα emission could be a way to detect such diffuse galaxies in our local universe.

Abstract Copyright: © ESO 2022

Journal keyword(s): galaxies: interactions - galaxies: star formation - techniques: imaging spectroscopy - galaxies: individual: J202258.73-441623.8 - galaxies: individual: NGC 6902A

Status at CDS : Examining the need for a new acronym.

Simbad objects: 1

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Number of rows : 1
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 ESO 285-4 G 20 23 00.3645739896 -44 16 13.582984044   14.42   13.09   ~ 25 0

Query : 2022A&A...657L..10Y

Basic data :
ESO 285-4 -- Galaxy
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types: 		G (2011MNRAS,ESO,...), * (Gaia)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) : 		20 23 00.3645739896 -44 16 13.582984044 (Optical) [ 6.4072 3.4452 90 ] C 2020yCat.1350....0G
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) : 		20 19 33.2788329947 -44 25 53.132757640 [ 6.4072 3.4452 90 ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) : 		356.0898395275515 -34.4854176906636 [ 6.4072 3.4452 90 ]
Syntax of radial velocity (or/and redshift) is : "value [error] (wavelength) quality bibcode"
  • value : radial velocity or/and redshift (Heliocentric frame) according to your Output Options
    (redshift may be not displayed if the data value is <0 and the database inside value is a radial velocity)
  • [error] : error of the corresponding value displayed before
  • (wavelength) : wavelength range of the measurement : Rad, mm, IR, Opt, UV, Xray, Gam or  '∼'(unknown)
  • quality : flag of quality ( A=best quality -> E=worst quality, ∼=unknown quality)
  • bibcode : bibcode of the value's origin
Radial velocity / Redshift / cz : 		V(km/s) 16188 [3] / z(~) 0.055538 [0.000010] / cz 16649.87 [3.00]
   D 2002LEDA.........0P
Syntax of morphological type is : mtype quality bibcode
  • mtype : Hubble morphological class (spirals, ellipticals, etc)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the morphological type reference
Morphological type: 		-2.0 D 1989ESOLV.C......0L
Syntax of angular size is : "maj-axis min-axis angle (wtype) quality bibcode"
  • maj-axis : major axis size (arc minutes)
  • min-axis : minor axis size (arc minutes)
  • angle : orientation angle (in degrees)
  • (wtype) : wavelength class for the origin of the angular size (Rad, mm, IR, Opt, UV, Xray, Gam)
  • quality : flag of quality of the angular size values ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the angular size reference
Angular size (arcmin): 		0.793 0.381 60 (NIR) C 2006AJ....131.1163S
Syntax of fluxes (or magnitudes) is : "filter-name (System) flux-value [error] quality MultVarFlags bibcode"
  • filter-name : U, B, V, R, I, G, J, H, K, u, g, r, i, z
  • (System) : may be AB (default is Vega)
  • flux-value : value of flux or magnitude
  • [error] : error value
  • quality : flag of quality of the flux value ( A=best quality -> E=worst quality, {� } =unknown quality)
  • MultVarFlags : Mult is zero or one char (J) for joined photometry ; Var can be zero or two chars (V[0-4])
  • bibcode : bibcode of the flux reference
Fluxes (6) :
B 14.42 [~] C 1989ESOLV.C......0L
R 13.09 [~] C 1989ESOLV.C......0L
G 20.390383 [0.016708] C 2020yCat.1350....0G
J 11.599 [0.031] C 2006AJ....131.1163S
H 10.891 [0.033] C 2006AJ....131.1163S
K 10.877 [0.062] C 2006AJ....131.1163S
SIMBAD within arcmin
', {sourceSize:12, color:'#30a090'})); aladin.on('objectClicked', function(object) { var objName=object.data.MAIN_ID; aladin.showPopup(object.ra,object.dec,'',''+ objName+''); });" title="Show Simbad objects"> Overlay Simbad points in this preview
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The search radius has to be specified by the user. It is currently limited to a maximum of 30 arcsec. It depends mostly on the precision or quality of the coordinates (SIMBAD and VizieR catalogs), the resolution of the images from which the sources were extracted, source extent, and source crowding.
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Hierarchy : number of linked objects
whatever the membership probability is (see description here ) :

: 1 : 2 Display criteria :

The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature.
Identifiers (12) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

ESO 285-4 ESO-LV 285-0040 2MASX J20230037-4416138 Ser 136-4
AM 2019-442 JB a 33 MCG-07-41-032 SGC 201933-4426.0
6dFGS gJ202300.4-441614 LEDA 64575 NGC 6902A Gaia DR3 6678916935489683712

References (25 between 1850 and 2024) (Total 25)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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Collections of Measurements


velocities : 2   

   

External archives :

Data at NED - NASA/IPAC Extragalactic Database : ESO 285-4

Link by name to the catalogue in VizieR :

ESO-LV 285-0040 2MASX J20230037-4416138 Gaia DR3 6678916935489683712

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