View source for Astronomy:Bedin I

{{Short description|Dwarf spheroidal galaxy located in the constellation Pavo}}
{{Sky|19|10|45.41|-|59|55|04.32}}
{{Infobox galaxy
| name               = Bedin I
| image              = The accidentally discovered galaxy Bedin I.tif
| epoch              = [[Astronomy:J2000|J2000]]
| constellation name = [[Astronomy:Pavo (constellation)|Pavo]]
| ra                 = {{RA|19|10|45.41}}
| dec                = {{DEC|-59|55|04.32}}
| dist_ly            = {{Val|8.7|+0.5|−0.7}} [[Astronomy:Parsec#Megaparsecs and gigaparsecs|Mpc]]
| appmag_v           = 19.94
| absmag_v           = −9.76
| size               = 840 × 340 [[Astronomy:Parsec|pc]]
| size_v             = 20" × 8"
}}

'''Bedin I''' is a [[Astronomy:Dwarf spheroidal galaxy|dwarf spheroidal galaxy]] located in the constellation [[Astronomy:Pavo (constellation)|Pavo]]. It is situated around 28.38 million [[Astronomy:Light-year|light-year]]s from Earth, behind the [[Astronomy:Globular cluster|globular cluster]] [[Astronomy:NGC 6752|NGC 6752]]. Bedin I is possibly one of the oldest galaxies known, having formed around 10–13 billion years ago, and is one of the most isolated dwarf galaxies known, situated around 2.12 million light-years away from [[Astronomy:NGC 6744|NGC 6744]], its nearest neighbor with which it may be physically associated. As such, it has been deemed by astronomers as a "fossil" from the [[Astronomy:Chronology of the universe|early universe]]. It was accidentally discovered by Italian astronomer Luigi Bedin, whose team was studying [[Astronomy:White dwarf|white dwarf]]s in NGC 6752 using the [[Astronomy:Hubble Space Telescope|''Hubble'' Space Telescope]] in September 2018; the discovery was announced in a paper published in January 2019.

== Nomenclature ==
Bedin I, pronounced {{IPAc-en|b|ɛ|'|d|i:|n}},<ref>{{Cite AV media|date=6 February 2019|title=Hubble discovers nearby galaxy - Bedin 1|language=English|url=https://www.youtube.com/watch?v=yn3WWVzpT_E| archive-url=https://ghostarchive.org/varchive/youtube/20211116/yn3WWVzpT_E| archive-date=2021-11-16 | url-status=live|access-date=21 February 2019|time=3:41|publisher=Launch Pad Astronomy, [[Company:YouTube|YouTube]]|quote=...designated '''Bedin''' I}}{{cbignore}}</ref> was named by its discovery team after their leader, Luigi Bedin,<ref>{{Harvard citation no brackets|Plait|2019|loc="which the astronomers named Bedin I, after the lead investigator on the team, Luigi Bedin"}}</ref><ref name="spacecom-1">{{Cite web|last1=Wall|first1=Mike|title=Hubble Telescope Discovers 'Living Fossil' Galaxy in Our Milky Way's Backyard|url=https://www.space.com/43191-hubble-telescope-living-fossil-galaxy-discovery.html|website=Space.com|access-date=1 February 2019|archive-url=https://web.archive.org/web/20190201022347/https://www.space.com/43191-hubble-telescope-living-fossil-galaxy-discovery.html|archive-date=1 February 2019|date=31 January 2019|quote=The find was fortuitous. An international team of astronomers was using Hubble's Advanced Camera for Surveys instrument to study white dwarfs [...] nicknamed Bedin 1, after discovery team leader L. R. Bedin of the INAF-Osservatorio Astronomico di Padova in Italy...|url-status=live}}</ref> who is a researcher at the [[Organization:INAF|National Institute for Astrophysics]]'s observatory in Padua, Italy.<ref name="spacecom-1"/><ref name="phys-1">{{Cite web|author=Instituto de Astrofísica de Canarias|title=After the Kepler supernova explosion, no survivors were left behind |url=https://phys.org/news/2018-08-kepler-supernova-explosion-survivors-left.html|website=Phys.org|access-date=1 February 2019|archive-url=https://web.archive.org/web/20190201021826/https://phys.org/news/2018-08-kepler-supernova-explosion-survivors-left.html|archive-date=1 February 2019|date=1 August 2018|quote=...says Luigi Bedin, researcher at Osservatorio Astronomico di Padova (INAF)|url-status=live|author-link=Instituto de Astrofísica de Canarias }}</ref> He was credited as the galaxy's sole discoverer.<ref name="nbc-1">{{Cite web|last=Freeman|first=David|title=Tiny 'oddball' galaxy discovered lurking in our cosmic backyard|url=https://www.nbcnews.com/mach/science/tiny-oddball-galaxy-discovered-lurking-our-cosmic-backyard-ncna965546|website=NBC News MACH|access-date=1 February 2019|archive-url=https://web.archive.org/web/20190201053923/https://www.nbcnews.com/mach/science/tiny-oddball-galaxy-discovered-lurking-our-cosmic-backyard-ncna965546|archive-date=1 February 2019|date=31 January 2019|quote=The newfound galaxy, dubbed Bedin 1 in an acknowledgment of the scientist's singular role in its discovery [...] It's about 30 times smaller than the Milky Way and a thousand times dimmer.|url-status=live}}</ref> Bedin and the team opted to avoid the galaxy being given "an anonymous identification based on its coordinates."<ref name="gizmodo-1">{{Cite web|last=Dvorsky|first=George|title=Astronomers Accidentally Discover a Hidden Galaxy Right Next Door|url=https://gizmodo.com/astronomers-accidentally-discover-a-hidden-galaxy-right-1832262574?IR=T|website=Gizmodo|access-date=2 February 2019|archive-url=https://web.archive.org/web/20190202010910/https://gizmodo.com/astronomers-accidentally-discover-a-hidden-galaxy-right-1832262574?IR=T|archive-date=2 February 2019|date=1 February 2019|quote=Bedin 1 is located in the Pavo constellation [...] Bedin said he pleased with the galaxy's new name, saying it was "nice to adopt a nickname from one of its discoverers instead of an anonymous identification based on its coordinates."|url-status=live}}</ref>

== Characteristics ==
Bedin I is an isolated dwarf spheroidal galaxy located around 8.7 megaparsecs, or around 28.38 million light-years, from Earth,<ref name="bedin-2">{{Harvard citation no brackets|Bedin et al.|2019|loc="Assuming the same reddening as for NGC 6752, we estimate a distance modulus of (m − M)<sub>0</sub> = {{Val|29.70|0.13}} from the observed red giant branch, i.e. 8.7 ± 0.5−0.7 Mpc, and size of ~840 × 340 pc, about one-fifth the size of the Large Magellanic Cloud."}}</ref><ref name="bedin-3">{{Harvard citation no brackets|Bedin et al.|2019|loc="We conclude that this object is most likely an isolated dwarf spheroidal galaxy [...] The size and the estimated ellipticity of Bedin I offer the closest resemblance to the Tucana dwarf spheroidal galaxy. KKR 25 is an almost identical isolated dwarf system, with similar luminosity...}}</ref><ref name="independent-1">{{Cite web|last=Griffin|first=Andrew|title=Astronomers accidentally find a tiny galaxy that is nearly as old as the universe itself|url=https://www.independent.co.uk/news/science/hubble-nasa-esa-space-image-astronomers-galaxy-universe-old-as-fossil-a8758131.html|website=The Independent|access-date=2 February 2019|archive-url=https://web.archive.org/web/20190202013609/https://www.independent.co.uk/news/science/hubble-nasa-esa-space-image-astronomers-galaxy-universe-old-as-fossil-a8758131.html|archive-date=2 February 2019|date=1 February 2019|quote=Together, those porperties led astronomers to classify it as what is called a dwarf spheroidal galaxy. [...] Because it is so distant from any other galaxies – and so has been left largely undisturbed – as well as its old age, the astronomers refer to Bedin 1 as a fossil from the beginning of the cosmos.|url-status=live}}</ref> with similar characteristics to [[Astronomy:KKR 25|KKR 25]] and the [[Astronomy:Tucana Dwarf|Tucana Dwarf Galaxy]].<ref name="bedin-3"/> It is estimated to be around 840 by 340 [[Astronomy:Parsec|parsec]]s, or 2,700 by 1,100 [[Astronomy:Light-year|light-year]]s, in size, which is a fifth the size of the [[Astronomy:Large Magellanic Cloud|Large Magellanic Cloud]].<ref name="bedin-2"/> At a [[Astronomy:Metallicity|metallicity]] of −1.3, the galaxy's population is made up of metal-poor [[Astronomy:Red giant|red giant]] stars,<ref name="bedin-4">{{Harvard citation no brackets|Bedin et al.|2019|loc="A comparison of the observed colour–magnitude diagram with synthetic counterparts, which account for the galaxy distance modulus, reddening, and photometric errors, suggests the presence of an old (~13 Gyr) and metal-poor ([Fe/H] ~ −1.3) population."}}</ref><ref>{{Harvard citation no brackets|Plait|2019|loc="Still, enough individual stars are visible for the astronomers to examine them carefully. They were able to find quite a few red giant stars..."}}</ref> and its luminosity is roughly a thousand times dimmer than the [[Astronomy:Milky Way|Milky Way Galaxy]],<ref name="nbc-1"/><ref name="forbes-1">{{Cite web|last=Carter|first=Jamie|title=The Milky Way Has A New Neighbor. Accidental Discovery As Ancient Galaxy Photobombs Hubble Telescope|url=https://www.forbes.com/sites/jamiecartereurope/2019/01/31/the-milky-way-has-a-new-neighbor-accidental-discovery-as-ancient-galaxy-photobombs-hubble-telescope/#616abec05e7c|website={{wipe|Forbes}}|access-date=1 February 2019|archive-url=https://archive.today/20190201054934/https://www.forbes.com/|archive-date=1 February 2019|date=31 January 2019|quote=The astronomers that fortuitously discovered Bedin 1 were on a hunt for white dwarf stars in an effort to measure the age of NGC 6752 [...] it is roughly a thousand times dimmer than our Milky Way.|url-status=live}}</ref> at an [[Astronomy:Absolute magnitude|absolute magnitude]] of −9.76.<ref name="bedin-5">{{Harvard citation no brackets|Bedin et al.|2019|loc="<sup>a</sup>max<sup>-axis</sup> ~20 arcsec (~840 pc); <sup>b</sup>max<sup>-axis</sup> ~8 arcsec (~340 pc); <sup>m</sup>F606W 19.94; <sup>M</sup>F606W −9.76"}}</ref> Bedin I is believed to have formed around 10–13 billion years ago with no star formation having occurred since then,<ref name="bedin-4"/><ref>{{Harvard citation no brackets|Bedin et al.|2019|loc="We conclude that this system likely formed more than 10 Gyr ago in a 'single' burst, and likely experienced no additional star formation since its formation."}}</ref><ref name="esahubble-1">{{Cite web|last1=Bedin|first1=Luigi|last2=Jäger|first2=Mathias|title=Hubble fortuitously discovers a new galaxy in the cosmic neighbourhood|url=https://www.spacetelescope.org/news/heic1903/|website=ESA/Hubble|access-date=1 February 2019|archive-url=https://web.archive.org/web/20190201041001/https://www.spacetelescope.org/news/heic1903/|archive-date=1 February 2019|date=31 January 2019|quote=It lies about 30 million light-years from the Milky Way and 2 million light-years from the nearest plausible large galaxy host, NGC 6744. This makes it possibly the most isolated small dwarf galaxy discovered to date. [...] astronomers were able to infer that the galaxy is around 13 billion years old — nearly as old as the Universe itself.|url-status=live}}</ref> making it one of the oldest galaxies known.<ref name="esahubble-1"/><ref name="nasasse-1">{{Cite web|last1=Bedin|first1=Luigi|last2=Villard|first2=Ray|title=Hubble Accidentally Discovers a New Galaxy in Cosmic Neighborhood|url=https://solarsystem.nasa.gov/news/831/hubble-accidentally-discovers-a-new-galaxy-in-cosmic-neighborhood/|website=[[Organization:NASA|NASA Solar System Exploration]]|access-date=1 February 2019|archive-url=https://web.archive.org/web/20190201032113/https://solarsystem.nasa.gov/news/831/hubble-accidentally-discovers-a-new-galaxy-in-cosmic-neighborhood/|archive-date=1 February 2019|date=31 January 2019|quote=Because of its 13-billion-year-old age, and its isolation — which resulted in hardly any interaction with other galaxies — the dwarf is the astronomical equivalent of a living fossil from the early universe. [...] The science team's results will be published online January 31, 2019, in the Monthly Notices of the Royal Astronomical Society: Letters.|url-status=live}}</ref> Bedin I is also possibly the most isolated dwarf galaxy known,<ref name="esahubble-1"/> located at least 650 kiloparsecs, or 2.12 million light-years, from its nearest neighbor, the [[Astronomy:Intermediate spiral galaxy|intermediate spiral galaxy]] NGC 6744;{{Efn|Bedin I is ~650 kiloparsecs from NGC 6744 along the [[Longitude of the ascending node|plane of the sky]]. More accurate measurements to judge its horizontal distance, and thus its true distance from NGC 6744, are needed.<ref name="bedin-6">{{Harvard citation no brackets|Bedin et al.|2019|loc="...but could be associated with NGC 6744. Indeed, NGC 6744 has a distance of {{Val|9.15|0.40}} Mpc (Tully et al. 2013 catalogue gives (m − M)<sub>0</sub> = {{Val|29.81|0.09}}), i.e. consistent with the dwarf within uncertainties, and it is at an angular distance of about 4 ° from the dwarf spheroidal (so, at a minimum distance of ~650 kpc on the plane of the sky). [...] Our photometry is too shallow to reach the horizontal branch..."}}</ref>}} the Milky Way and [[Astronomy:Andromeda Galaxy|Andromeda]] galaxies are separated by a similar distance.<ref>{{Harvard citation no brackets|Plait|2019|loc="It does appear to be in the same region of sky and at about the same distance as the big spiral NGC 6744, but even then they're separated by at least two million light years, a huge distance (Andromeda is about that far from the Milky Way)..."}}</ref> A physical association with NGC 6744 has been speculated however, due to the close [[Astronomy:Angular distance|angular distance]] between the galaxies, and their similar physical distances from Earth.<ref name="bedin-6"/> Its age, isolation, and lack of interaction with other galaxies has led to the galaxy being deemed a "fossil" from the [[Astronomy:Chronology of the universe|early universe]].<ref name="nasasse-1"/><ref name="independent-1"/>

== Observation ==
Bedin I is located in the constellation Pavo,<ref name="gizmodo-1"/> at a [[Right ascension|right ascension]] of {{RA|19|10|45.41}} and [[Declination|declination]] of {{DEC|-59|55|04.32}}.<ref name="hubblesite-1"/> The galaxy is situated behind a group of unnamed foreground stars within the globular cluster NGC 6752.<ref name="plait-1"/><ref name="phys-2">{{Cite web|author=ESA/Hubble Information Centre|title=Hubble fortuitously discovers a new galaxy in the cosmic neighbourhood|url=https://phys.org/news/2019-01-hubble-fortuitously-galaxy-cosmic-neighbourhood.html|website=Phys.org|access-date=1 February 2019|archive-url=https://web.archive.org/web/20190201050615/https://phys.org/news/2019-01-hubble-fortuitously-galaxy-cosmic-neighbourhood.html|archive-date=1 February 2019|date=31 January 2019|quote=The aim of their observations was to use these stars to measure the age of the globular cluster, [...] Bedin 1, which lies far behind the foreground globular cluster NGC 6752.|url-status=live}}</ref> Bedin I measures around 20 by 8 [[Minute and second of arc|arcseconds]] across and has an [[Astronomy:Apparent magnitude|apparent magnitude]] of 19.94,<ref name="bedin-5"/><ref>{{Harvard citation no brackets|Plait|2019|loc="Their combined light brings this galaxy to a magnitude of about 20..."}}</ref> although its visibility is significantly decreased by NGC 6752, one of the brightest globular clusters in the sky with an apparent magnitude of 5.4.<ref>{{Cite web|last1=Bonnell|first1=Jerry|last2=Nemiroff|first2=Robert J.|title=Globular Star Cluster NGC 6752|url=https://apod.nasa.gov/apod/ap130705.html|access-date=12 August 2019|archive-url=https://web.archive.org/web/20190812084443/https://apod.nasa.gov/apod/ap130705.html|archive-date=12 August 2019|date=5 July 2013|quote=Over 10 billion years old, NGC 6752 follows clusters Omega Centauri and 47 Tucanae as the third brightest globular in planet Earth's night sky.|url-status=live}}</ref><ref name="o'meara-1">{{Cite book|last=O'Meara|first=Stephen James|title=Deep-Sky Companions: Southern Gems|date=8 April 2013|publisher={{wipe|Cambridge University Press}}|isbn=978-1-107-01501-2|page=411|chapter-url=https://books.google.com/books?id=S5QIEKns33sC&pg=PA411|chapter=113 ''The Starfish, The Windmill'' NGC 6752|quote=At magnitude 5.4, it can be seen with the naked eye, and it ranks 5th among the globular clusters in total brightness.}}</ref> Bedin I was accidentally discovered by a team researching white dwarfs in the cluster in an effort to better determine the cluster's age.<ref name="spacecom-1"/><ref name="forbes-1"/><ref name="phys-2"/> The galaxy partially appeared in the field of view during program GO-15096 of the ''Hubble'' Space Telescope, led by [[Principal investigator|principal investigator]] Luigi R. Bedin, which occurred between 7 and 18 September 2018.<ref name="bedin-1"/><ref name="bedin-7">{{Harvard citation no brackets|Bedin et al.|2019|loc="All images for this study were collected with the Wide Field Channel (WFC) of the Advanced Camera for Surveys (ACS) at the focus of the HST under program GO-15096 (PI: Bedin). Unfortunately, 5 of the planned 40 orbits failed because of poor guide star acquisition and will be reobserved at a later time. Usable data were collected between 2018 September 7 and 18, and consist of deep exposures of 1270 s each"}}</ref> The program, which saw the Wide Field Channel (WFC) of the [[Engineering:Advanced Camera for Surveys|Advanced Camera for Surveys]] (ACS) pointed at NGC 6752 for 75 exposures lasting 1,270 seconds each, was conducted over 40 orbits;<ref name="bedin-7"/> these exposures were able to capture objects with an apparent magnitude above 30.<ref>{{Harvard citation no brackets|Bedin et al.|2019|loc="...an Advanced Camera for Surveys/Wide Field Channel field was the subject of deep optical observations reaching magnitudes as faint as V ~ 30."}}</ref> Five of the orbits failed however, due to poor guide star acquisition.<ref name="bedin-7"/> The journal ''[[Organization:Monthly Notices of the Royal Astronomical Society|Monthly Notices of the Royal Astronomical Society: Letters]]'' published the team's three-part [[Scientific literature#Scientific article|scientific paper]] on findings from the program on 31 January 2019, with the first part dedicated to the discovery of Bedin I.<ref name="nasasse-1"/><ref name="bedin-8">{{Harvard citation no brackets|Bedin et al.|2019|loc="For completeness, Paper III of this series is focused on the white dwarfs of NGC 6752 in this very same ACS/WFC field, while Paper II deals with multiple stellar populations detected within NGC 6752 in our parallel observations with the infrared channel of the Wide Field Camera 3 (WFC3)."}}</ref> A second program of 40 orbits, GO-15491, is currently scheduled for late 2019.<ref>{{Harvard citation no brackets|Bedin et al.|2019|loc="Note that this is an astrometric multicycle programme, and a second epoch (also of 40 orbits) has already been approved (GO-15491) and scheduled for late 2019."}}</ref>

== See also ==
* [[Astronomy:List of galaxies named after people|List of galaxies named after people]]
* [[Astronomy:List of nearest galaxies|List of nearest galaxies]]
{{Clear}}

== References ==
'''Notes'''
{{Notelist}}
'''Sources'''
{{Refbegin}}
# {{Cite journal|last1=Bedin|first1=Luigi|last2=Salaris|first2=Maurizio|last3=Rich|first3=R. Michael|last4=Richer|first4=Harvey|last5=Anderson|first5=Jay|last6=Bettoni|first6=Daniela|last7=Nardiello|first7=Domenico|last8=Milone|first8=Antonio P.|last9=Marino|first9=A. F.|last10=Libralato|first10=Mattia|last11=Bellini|first11=Andrea|last12=Dieball|first12=Andrea|last13=Bergeron|first13=Pierre|last14=Burgasser|first14=Adam J.|last15=Apai|first15=Daniel|title=The HST Large Programme on NGC 6752. I. Serendipitous discovery of a dwarf Galaxy in background|journal=[[Organization:Monthly Notices of the Royal Astronomical Society|Monthly Notices of the Royal Astronomical Society: Letters]]|date=10 January 2019|volume=484|issue=1|pages=L54–L58|doi=10.1093/mnrasl/slz004|url=https://academic.oup.com/mnrasl/article/484/1/L54/5288002|access-date=31 January 2019|publisher=[[Organization:Oxford University Press|Oxford University Press]]|archive-url=https://web.archive.org/web/20190131222539/https://academic.oup.com/mnrasl/article/484/1/L54/5288002|archive-date=31 January 2019|url-status=live|ref={{SfnRef|Bedin et al.|2019}}|doi-access=free|hdl=10150/634469|hdl-access=free}}
# {{Cite web|last=Plait|first=Phil|title=Astronomers accidentally discover a nearby galaxy in a Hubble image!|url=https://www.syfy.com/syfywire/astronomers-accidentally-discover-a-nearby-galaxy-in-a-hubble-image|website=Syfy Wire|access-date=2 February 2019|archive-url=https://web.archive.org/web/20190202000138/https://www.syfy.com/syfywire/astronomers-accidentally-discover-a-nearby-galaxy-in-a-hubble-image|archive-date=2 February 2019|date=1 February 2019|url-status=live}}
{{Refend}}
'''Citations'''
{{Reflist}}

== External links ==
* [https://academic.oup.com/mnrasl/article/484/1/L54/5288002 The HST Large Programme on NGC 6752. I. Serendipitous discovery of a dwarf Galaxy in background] [[File:Lock-green.svg|9px|link=|alt=Freely accessible|Freely accessible]] at ''[[Organization:Monthly Notices of the Royal Astronomical Society|Monthly Notices of the Royal Astronomical Society: Letters]]'' <small>([https://web.archive.org/web/20190131222539/https://academic.oup.com/mnrasl/article/484/1/L54/5288002 Archived] 31 January 2019)</small>

{{Stars of Pavo|state=collapsed}}

{{DEFAULTSORT:Bedin I}}
[[Category:Dwarf spheroidal galaxies]]
[[Category:Pavo (constellation)]]

{{Sourceattribution|Bedin I}}