{{Short description|Interacting pair in the constellation of Boötes}} {{Infobox galaxy|name=VV 191|epoch=[[J2000]]|constellation name=[[Boötes]]|ra={{RA|13|48|21.77}}<ref name="ned" />|dec={{DEC|+25|40|31.11}}<ref name="ned" />|z=0.051297<ref name="ned" />|h_radial_v=15,378 [[kilometer per second|km/s]]<ref name="ned" />|dist_ly={{convert|227.32 ± 15.91|Mpc|Mly|abbr=on|lk=on|order=flip}}<ref name="ned" />|image=File:Galaxy Pair VV 191 (Webb and Hubble Composite Image) (VV191a).jpeg|caption=The galaxy pair VV 191 captured by both [[Hubble Space Telescope|HST]] and [[James Webb Space Telescope|JWST]]|mag_j=13.35<ref name="ned" />|size=~{{convert|106.9|kpc|ly|abbr=on|lk=on|order=flip}} (estimated) (VV 191a), ~{{convert|41.13|kpc|ly|abbr=on|lk=on|order=flip}} (estimated) (VV 191b)|names=HOLM 544, [[Catalogue of Galaxies and of Clusters of Galaxies|CGCG]] 132-015, [[Principal Galaxies Catalogue|PGC]] 48974/48981, [[Morphological Catalogue of Galaxies|MCG]] +04-33-006 and MCG +04-33-005, PGC 48973/48980}}
'''VV 191''' known as '''HOLM 544''',<ref>{{Cite web |title=NED Search results for VV 191 |url=https://ned.ipac.caltech.edu/byname?objname=VV+191&hconst=67.8&omegam=0.308&omegav=0.692&wmap=4&corr_z=1 |access-date=2026-02-22 |website=NASA/IPAC Extragalactic Database}}</ref> is a pair of [[Interacting galaxy|interacting galaxies]]{{cn|date=February 2026|reason=The article states they are physically separated, so a source is needed to demonstrate they are interacting.}} in the constellation of [[Boötes]]. It has been classified as an overlapping pair, where the [[spiral galaxy]] is described as backlit by an [[elliptical galaxy]] companion.<ref name=":0">{{Cite journal |last=Robertson |first=Clayton D. |last2=Holwerda |first2=Benne W. |last3=Berkheimer |first3=Jessica M. |last4=Butrum |first4=Trevor |last5=Castellano |first5=Ian |last6=Cook |first6=Kyle W. |last7=Keel |first7=William C. |last8=Koekemoer |first8=Anton M. |last9=Patel |first9=Divya |last10=del Carmen Polletta |first10=Maria |last11=Windhorst |first11=Rogier A. |date=2025-09-02 |title=Mapping Interstellar Dust in the Foreground Outer Disk of Overlapping Galaxy Pair VV 191 with HST and JWST |url=https://doi.org/10.3847/1538-3881/adf6aa |journal=The Astronomical Journal |volume=170 |issue=4 |pages=195 |doi=10.3847/1538-3881/adf6aa |doi-access=free|issn=0004-6256}}</ref><ref>{{Cite web |last=information@eso.org |title=Galaxy Pair VV 191 (Webb and Hubble Composite Image) {{!}} ESA/Webb |url=https://esawebb.org/images/VV191a/ |access-date=2026-02-22 |website=esawebb.org |language=en}}</ref>
== Description == VV 191 is made up of two separate galaxies. The first galaxy is '''VV 191a''' and it has been classified as an elliptical galaxy. Its [[redshift]] has been estimated to be at (z) 0.0512 or (z) 0.0513.<ref name="ned">{{Cite web |title=NED Search Results for VV 191a |url=https://ned.ipac.caltech.edu/byname?objname=VV+191a&hconst=67.8&omegam=0.308&omegav=0.692&wmap=4&corr_z=1 |access-date=2026-02-22 |website=NASA/IPAC Extragalactic Database}}</ref><ref>{{Cite journal |last=Berkheimer |first=Jessica M. |last2=Carleton |first2=Timothy |last3=Windhorst |first3=Rogier A. |last4=Keel |first4=William C. |last5=Holwerda |first5=Benne W. |last6=Nonino |first6=Mario |last7=Cohen |first7=Seth H. |last8=Jansen |first8=Rolf A. |last9=Coe |first9=Dan |last10=Conselice |first10=Christopher J. |last11=Driver |first11=Simon P. |last12=Frye |first12=Brenda L. |last13=Grogin |first13=Norman A. |last14=Koekemoer |first14=Anton M. |last15=Lucas |first15=Ray A. |date=2024-03-28 |title=JWST NIRCam Photometry: A Study of Globular Clusters Surrounding Bright Elliptical Galaxy VV 191a at z = 0.0513 |url=https://doi.org/10.3847/2041-8213/ad2688 |journal=The Astrophysical Journal Letters |volume=964 |issue=2 |pages=L29 |doi=10.3847/2041-8213/ad2688 |doi-access=free|issn=2041-8205}}</ref> The second galaxy in the system, '''VV 191b''', has been classified as a multi-armed spiral galaxy of type Sc<ref name=":0" /> and has a redshift of (z) 0.0514.<ref name=":1">{{Cite web |title=NED Search results for VV 191b |url=https://ned.ipac.caltech.edu/byname?objname=VV+191b&hconst=67.8&omegam=0.308&omegav=0.692&wmap=4&corr_z=1 |access-date=2026-02-22 |website=NASA/IPAC Extragalactic Database}}</ref> The pair of galaxies have been described as overlapping, but in reality they are separated physically. VV 191a is also a background galaxy, with an extension of up to around 1.7 [[Parsec|kiloparsecs]] from the center of the spiral galaxy companion. A study also found the spiral galaxy is rotating [[Symmetry|symmetrically]], with its [[Dust lane|dust lanes]] being described as both partially overlapping and nonoverlapping.<ref>{{Cite journal |last=Robertson |first=Clayton |last2=Holwerda |first2=Benne W. |last3=Young |first3=Jason |last4=Keel |first4=William C. |last5=Berkheimer |first5=Jessica M. |last6=Cook |first6=Kyle |last7=Conselice |first7=Christopher J. |last8=Frye |first8=Brenda L. |last9=Grogin |first9=Norman A. |last10=Koekemoer |first10=Anton M. |last11=Nasr |first11=Camella-Rosa |last12=Patel |first12=Divya |last13=Roemer |first13=Wade |last14=Smith |first14=Dominic |last15=Windhorst |first15=Rogier A. |date=2024-05-14 |title=Ground- and Space-based Dust Observations of VV 191 Overlapping Galaxy Pair |url=https://doi.org/10.3847/1538-3881/ad39c4 |journal=The Astronomical Journal |volume=167 |issue=6 |pages=263 |doi=10.3847/1538-3881/ad39c4 |doi-access=free|issn=0004-6256}}</ref> The nuclei of the galaxies are estimated to be 20.6 kiloparsecs away from each other.
A study published in March 2024, records 154 [[Globular cluster|globular clusters]] around the elliptical galaxy, with most having an estimated mass of around 10<sup>6.5</sup> [[Solar mass|M<sub>☉</sub>]]. The spiral companion contains a population of young stars with mean ages of 10<sup>7</sup> to 10<sup>8</sup> million years.<ref name=":1" /> A [[photodissociation region]] has also been discovered in the outer disk of the spiral galaxy 17 kiloparsecs from the optical center and there is evidence of a [[spiral arm]] dust cavity feature surrounding the entire region. This indicates the production of [[polycyclic aromatic hydrocarbon]] emission.<ref>{{Cite journal |last=Robertson |first=Clayton D. |last2=Holwerda |first2=Benne W. |last3=Berkheimer |first3=Jessica M. |last4=Cook |first4=Kyle W. |last5=Keel |first5=William C. |last6=Windhorst |first6=Rogier A. |date=2025-04-18 |title=Discovery of Photodissociation Region in Overlapping Galaxy Pair VV 191 with HST and JWST |url=https://doi.org/10.3847/2515-5172/adcd6c |journal=Research Notes of the AAS |volume=9 |issue=4 |pages=90 |doi=10.3847/2515-5172/adcd6c |doi-access=free|issn=2515-5172}}</ref> The dust lanes of the spiral galaxy continue beyond the region of the spiral arms which then trace in a complex web pattern. A [[lens]] arc is found a few arcseconds away from the center of the elliptical galaxy, suggesting the possibility of [[Gravitational lens|gravitational lensing]].<ref>{{Cite journal |last=Keel |first=William C. |last2=Windhorst |first2=Rogier A. |last3=Jansen |first3=Rolf A. |last4=Cohen |first4=Seth H. |last5=Summers |first5=Jake |last6=Holwerda |first6=Benne |last7=Bradford |first7=Sarah T. |last8=Robertson |first8=Clayton D. |last9=Ferrami |first9=Giovanni |last10=Wyithe |first10=Stuart |last11=Yan |first11=Haojing |last12=Conselice |first12=Christopher J. |last13=Driver |first13=Simon P. |last14=Robotham |first14=Aaron |last15=Grogin |first15=Norman A. |date=2023-03-20 |title=JWST’s PEARLS: Dust Attenuation and Gravitational Lensing in the Backlit-galaxy System VV 191 |url=https://doi.org/10.3847/1538-3881/acbdff |journal=The Astronomical Journal |volume=165 |issue=4 |pages=166 |doi=10.3847/1538-3881/acbdff |doi-access=free|issn=0004-6256|hdl=10261/335283 |hdl-access=free }}</ref>
== References == <references />
== External links == {{WikiSky}}
{{Boötes}} [[Category:Interacting galaxies]] [[Category:Boötes]] [[Category:Elliptical galaxies]] [[Category:Spiral galaxies]] [[Category:MCG objects|+04-33-006]] [[Category:Principal Galaxies Catalogue objects|048974]]