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Revision as of 23:53, 28 July 2017 edit2.25.45.251 (talk) it is known as the fireworks galaxy. it is not know by that other nonsense name from a nonsense list that someone has been spamming galaxy articles with.Tag: references removed← Previous edit Latest revision as of 18:26, 25 October 2024 edit undoA.sav (talk | contribs)Extended confirmed users3,062 editsm clean upTag: AWB 
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{{Short description|Galaxy in the constellations Cepheus & Cygnus}}
{{Disputed|about the dubious-discuss in diameter|date=October 2022}}
{{Use dmy dates|date=March 2024}}
{{Infobox Galaxy {{Infobox Galaxy
| name = ] 6946 | name = ] 6946
| image = ] | image = File:SpiralGalaxy NGC6946.jpg
| image_size = 300px
|caption = Spiral galaxy NGC 6946
| caption =A image of NGC 6946, the fireworks galaxy.
| epoch = ] | epoch = ]
| type = SAB(rs)cd<ref name="ned">{{cite web | type = SAB(rs)cd<ref name="ned"/>
| title=NASA/IPAC Extragalactic Database
| work=Results for NGC 6946
| url=http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+6946&img_stamp=yes&extend=no
| accessdate=2006-11-18 }}</ref>
| ra = {{RA|20|34|52.3}}<ref name="ned" /> | ra = {{RA|20|34|52.3}}<ref name="ned" />
| dec = {{DEC|+60|09|14}}<ref name="ned" /> | dec = {{DEC|+60|09|14}}<ref name="ned" />
| dist_ly = 25.2 ± 1.0 M]<br/>{{nowrap|7.72± 0.32 M])}}<ref name=Eldridgedistance>{{cite journal |last1=Eldridge |first1=J J |last2=Xiao |first2=Lin |date=2 March 2019 |title=The distance, supernova rate, and supernova progenitors of NGC 6946 |journal=Monthly Notices of the Royal Astronomical Society: Letters |volume=485 |issue=1 |pages=L58–L61 |doi=10.1093/mnrasl/slz030 |doi-access=free |arxiv=1903.00173 |bibcode=2019MNRAS.485L..58E |s2cid=118831398 }}</ref>
| dist_ly = 22.5 ± 7.8 M]<br/>{{nowrap|(6.9 ± 2.4 M])}}<ref name=ned-dist>{{cite web
| size = {{convert|26.77|kpc|ly|sigfig=3|abbr=on|lk=on}}<br />(diameter; ])<ref name="ned" /><ref name=RC3 />
|title=Distance Results for NGC 6946
| z = 0.000133<ref name=ned/>
|work=NASA/IPAC Extragalactic Database
|url=http://nedwww.ipac.caltech.edu/cgi-bin/nDistance?name=NGC+6946
|accessdate=2010-06-18}}</ref>
| z = 0.000160<ref name=ned/>
| h_radial_v = {{nowrap|48 ± 2 ]}}<ref name=ned/> | h_radial_v = {{nowrap|48 ± 2 ]}}<ref name=ned/>
| appmag_v = +9.6<ref name="ned" /> | appmag_v = +9.6<ref name="ned" />
| size_v = 16.0 x 11.2 ]<ref name="2MASS">{{Cite journal|title=The 2MASS Large Galaxy Atlas|author1=Jarrett, T. H.|author2=Chester, T.|author3=Cutri, R.|author4=Schneider, S. E.|author5=Huchra, J. P.|bibcode=2003AJ....125..525J|journal=The Astronomical Journal|issue=2|pages=525–554|year=2003|volume=125 |doi=10.1086/345794 |s2cid=117784410 |doi-access=free}}</ref>
| size_v = 11.5 x 9.8 ]<ref name="ned" />
| constellation name = ] &amp; ] | constellation name = ] &amp; ]
| names = ] 11597, ] 65001, ] 29,<ref name="ned" /> ] 12 | names = ] 11597, ] 65001, ] 29,<ref name="ned" /> ] 12}}
}}


'''NGC 6946''', sometimes referred to as the '''Fireworks Galaxy''', is a face-on ] with a small bright nucleus, whose location in the sky straddles the boundary between the ] ]s of ] and ]. Its distance from Earth is about 25.2&nbsp;million ]s or 7.72 ],<ref name=Eldridgedistance /> similar to the distance of ] (NGC 5457) in the ] ].<ref name="CAG1994"/> Both were once considered to be part of the ],<ref name="SEDS2013"/> but are now known to be among the dozen bright ] near the ] but beyond the confines of the ].<ref name="Efremov2017"/> NGC 6946 lies within the ].<ref>{{Cite web|url=http://ned.ipac.caltech.edu/level5/Dev2/frames.html|title=Nearby Groups of Galaxies|website=ned.ipac.caltech.edu|access-date=2018-05-03}}</ref>
'''NGC 6946''' (also known as the Fireworks Galaxy) is an ] about 22 million ]s away,<ref>{{Cite news|url=https://www.nasa.gov/mission_pages/chandra/multimedia/fireworks-galaxy-ngc6946.html

|title=NGC 6946: The 'Fireworks Galaxy'
The ] was discovered by ] on 9 September 1798. Based on an estimation by the Third Reference Catalogue of Bright Galaxies (RC3) in 1991, the galaxy has a ] of {{convert|26.77|kpc|ly|sigfig=3|abbr=off|lk=on}}.<ref name="ned" /><ref name=RC3 /> It is heavily obscured by ] due to its location close to the ] of the ].<ref>{{Cite web|url=http://www.messier.seds.org/xtra/supp/o_NED.html#n6946|title=NED data for some important Non-Messier Galaxies}}</ref> Due to its prodigious star formation it has been classified as an active ].<ref name="Efremov2017"/> NGC 6946 has also been classified as a double-barred spiral galaxy, with the inner, smaller bar presumably responsible for funneling gas into its center.<ref>{{cite journal |last1=Schinnerer |first1=Eva |last2=et |first2=al |date=2006 |title=Molecular Gas Dynamics in NGC 6946: A Bar-driven Nuclear Starburst ''Caught in the Act'' |url=https://ui.adsabs.harvard.edu/abs/2006ApJ...649..181S |journal=The Astrophysical Journal |volume=649 |issue=1 |pages=181–200 |doi=10.1086/506265 |access-date=|arxiv=astro-ph/0605702 |bibcode=2006ApJ...649..181S |s2cid=14717998 }}</ref><ref>{{cite journal |last1=Eibensteiner |first1=Cosima |last2=et |first2=al |date=2022 |title=A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946 |journal=Astronomy & Astrophysics |volume=659 |issue=A173 |pages= 37 |doi=10.1051/0004-6361/202142624 |arxiv=2201.02209 |bibcode=2022A&A...659A.173E |doi-access=free }}</ref>
|last=Boen|first=Brooke

|date=20 May 2015
Various unusual celestial objects have been observed within NGC 6946. This includes the so-called 'Red Ellipse' along one of the northern arms that looks like a super-bubble or very large supernova remnant, and which may have been formed by an open cluster containing massive stars. There are also two regions of unusual dark lanes of ], while within the spiral arms several regions appear devoid of stars and gaseous hydrogen, some spanning up to two kiloparsecs across.<ref name="Efremov2017"/>{{Dubious|about the dubious-discuss in diameter|reason=Based on what distance to the galaxy?|date=October 2022}} A third peculiar object, discovered in 1967, is now known as "Hodge's Complex".<ref name="Hodge1967"/> This was once thought to be a young ] cluster, but in 2017 it was conjectured to be an interacting dwarf galaxy superimposed on NGC 6946.<ref name="Efremov2017"/>
|newspaper=NASA
|access-date=2016-12-08}}</ref> in the ]s of ] and ]. It was discovered by ] on 9 September 1798. NGC 6946 is highly obscured by ] of the ], as it is quite close to the ]. The true diameter of the galaxy is approximately 40,000 light-years or just about one-third of the Milky Way's size.<ref>{{Cite APOD|title=Fireworks Galaxy NGC 6946 |date=1 January 2011 |access-date=}}</ref> In the past century, ten supernovae have been observed to explode in the arms of this galaxy, which has been classified as a ]. ] observations have, in fact, revealed three of the oldest supernovae ever detected in X-rays, giving more credence to its nickname. This composite image also includes optical data from the Gemini Observatory in red, yellow, and cyan.<ref></ref>


==Supernovae== ==Supernovae==
Ten ] have been observed in NGC 6946 in the 20th and early 21st century: ], ], ], ], ], ], ], ],<ref name="Li2005"/> ], and ].<ref name="Bishop-2017eaw"/><ref name=telegram1/><ref name=telegram2/><ref name=list/> For this reason, NGC 6946 has sometimes been referred to as the "Fireworks Galaxy".<ref name=gemini/><ref name=fireworks/> This is about ten times the rate observed in our ] galaxy,<ref name=gemini2005/> even though the Milky Way has twice as many stars as NGC 6946.


On 27 September 2004, the Type II supernova ] was observed at ] 15.2 and rose to a maximum visual magnitude of 12.7. Images taken during the preceding days revealed that the ] explosion occurred on 22 September. The progenitor of the supernova was identified on earlier images –– only the seventh time that such an event was directly identified with its host ]. The ] progenitor had an initial mass of about 15{{solar mass}} in an interacting ] shared with a ].<ref name="Li2005" />
Ten ] have been observed in NGC 6946 in the last 100 years: ], ], SN 1948B, SN 1968D, SN 1969P, SN 1980K, SN 2002hh, SN 2004et, SN 2008S, and SN 2017eaw.<ref>http://www.astronomerstelegram.org/?read=10372</ref><ref>http://www.astronomerstelegram.org/?read=10376</ref><ref name=list>{{cite web

During 2009, a bright ] within NGC 6946 flared up over several months to become over one million times as ] as the ]. Shortly thereafter it faded rapidly. Observations with the ] suggest that the star did not survive, although there remains some infrared emission from its position. This is thought to come from debris falling onto a ] that formed when the star died. This potential black hole-forming star is designated ].<ref name="Adams2016"/> The progenitor is believed to have been a ].<ref>{{Cite journal|last=Humphreys|first=Roberta M.|date=31 October 2019|title=Comments on the Progenitor of NGC 6946-BH1|journal=Research Notes of the AAS|volume=3|issue=10|pages=164|doi=10.3847/2515-5172/ab5191|issn=2515-5172|arxiv=1911.02037|bibcode=2019RNAAS...3..164H|s2cid=207880492 |doi-access=free }}</ref>

In May 2017, supernova ] was detected in the northwest region of the galaxy, and light curves obtained over the next 600 days showed that it was a ].<ref>{{Cite journal|last1=Buta|first1=Ronald J|last2=Keel|first2=William C|date=21 July 2019|title=BVRI photometry of the classic Type II-P supernova 2017eaw in NGC 6946: d 3 to d 594|url=https://academic.oup.com/mnras/article/487/1/832/5487895|journal=Monthly Notices of the Royal Astronomical Society|language=en|volume=487|issue=1|pages=832–844|doi=10.1093/mnras/stz1291|doi-access=free |issn=0035-8711|arxiv=1905.03084|bibcode=2019MNRAS.487..832B|s2cid=147703978}}</ref> The progenitor was determined to have been a ], with a mass of around 15{{solar mass}}.<ref>{{Cite journal|last1=Szalai|first1=Tamás|last2=Vinkó|first2=József|last3=Könyves-Tóth|first3=Réka|last4=Nagy|first4=Andrea P.|last5=Bostroem|first5=K. Azalee|last6=Sárneczky|first6=Krisztián|last7=Brown|first7=Peter J.|last8=Pejcha|first8=Ondrej|last9=Bódi|first9=Attila|last10=Cseh|first10=Borbála|last11=Csörnyei|first11=Géza|date=29 April 2019|title=The Type II-P Supernova 2017eaw: From Explosion to the Nebular Phase|journal=The Astrophysical Journal|volume=876|issue=1|pages=19|doi=10.3847/1538-4357/ab12d0|arxiv=1903.09048|bibcode=2019ApJ...876...19S|s2cid=84842034|issn=1538-4357 |doi-access=free }}</ref><ref name=KF18/>

As of 2017, more supernovae had been seen in NGC 6946 than in any other ],<ref name="Bishop-2017eaw">{{Cite web|url=https://rochesterastronomy.org/sn2017/sn2017eaw.html|title=Supernova 2017eaw in NGC 6946|quote=This is our most prolific galaxy with now 10 confirmed supernovae discovered.|first=David|last=Bishop|date=14 May 2017|access-date=2023-09-29}}</ref> a record that has since been surpassed by ].<ref name="MostProlific">{{Cite web|url=https://rochesterastronomy.org/snimages/sndupe.html|title=The most prolific galaxies|first=David|last=Bishop|date=27 August 2023|access-date=2023-09-29}}</ref>

{| class="wikitable sortable" style="text-align: center; font-size: 0.9em;"
|+Supernovae in NGC 6946<ref name="Bishop-2017eaw"/>
! Supernova
! ]
! type
|-
| 2017eaw || 12.6 || ]
|-
| 2008S || 16.5 || IIn-pec/]
|-
| 2004et || 12.3 || ]
|-
| 2002hh || 15.0 || II
|-
| 1980K || 11.4 || ]
|-
| 1969P || 13.9 || ?
|-
| 1968D || 13.5 || II
|-
| 1948B || 14.9 || II
|-
| 1939C || 13.0 || ?
|-
| 1917A || 14.6 || II
|}

==Gallery==
<gallery mode="packed" heights="200px">
File:NGC 6946 (Kitt Peak National Observatory) (2023-115).png|This image from the ] contextualizes the locations of ] and ] within the ].
File:NBO 2017eaw.png|Images of ] in NGC 6946, taken between May and November 2017, as the supernova was slowly fading
File:Giant star N6946-BH1 before and after it vanished out of sight by imploding to form a black hole.jpg|Pair of ] and near-infrared photos from the ] showing the giant star ] before and after it vanished out of sight by imploding to form a ]
File:Dusty supernovae (MIRI, annotated) (dustysupernovae2).jpg|NASA/ESA/CSA ] image of NGC 6946, revealing large amounts of ] from the two supernovae ] and ]
</gallery>

==See also==
*] – similar ] heavily obscured by ] ]s and ].
*]

==References==
{{Reflist|refs=

<ref name="ned">{{cite web
| title=NASA/IPAC Extragalactic Database
| work=Results for NGC 6946
| url=http://ned.ipac.caltech.edu/cgi-bin/objsearch?search_type=Obj_id&objid=48768&objname=1&img_stamp=YES&hconst=73.0&omegam=0.27&omegav=0.73&corr_z=1
| access-date=2022-10-29}}</ref>

<ref name=RC3>{{cite book | bibcode=1991rc3..book.....D | year=1991 | title=Third Reference Catalogue of Bright Galaxies | last1=De Vaucouleurs | first1=Gerard | last2=De Vaucouleurs | first2=Antoinette | last3=Corwin | first3=Herold G. | last4=Buta | first4=Ronald J. | last5=Paturel | first5=Georges | last6=Fouque | first6=Pascal }}</ref>

<ref name="CAG1994">{{cite book
|last1=Sandage|first1=A.
|last2=Bedke|first2=J.
|year=1994
|title=The Carnegie Atlas of Galaxies. Volume I
|publisher=Carnegie Institution of Washington
|bibcode=1994cag..book.....S}}</ref>

<ref name="Efremov2017">{{cite journal
|last1=Efremov|first1=Yu. N.
|title=Unusual Objects in the Spiral Galaxy NGC 6946
|journal=Open Astronomy
|year=2016
|volume=25
|issue=4
|pages=365–376
|bibcode=2016BaltA..25..369E|doi=10.1515/astro-2017-0255
|doi-access=free
}}</ref>

<!--<ref name=apod>{{Cite APOD|title=NGC 6946 : the Fireworks Galaxy|date=1 January 2011 |access-date=2 November 2017}}</ref> -->

<ref name="Hodge1967">{{cite journal
|last1=Hodge|first1=P.W.
|title=A Possible "Super-Supernova" Remnant in NGC 6946
|journal=Open Astronomy
|year=1967
|volume=79
|issue=466
|pages=466–470
|bibcode=1967PASP...79...29H
|doi=10.1515/astro-2017-0255|doi-access=free
}}</ref>

<ref name="Li2005">{{cite journal
|last1=Li|first1=W.
|last2=Van Dyk|first2=S.D.
|last3=Filippenko|first3=A.V
|last4=Cuillandre|first4=J.C.
|title=On the Progenitor of the Type II Supernova 2004et in NGC 6946
|journal=Publications of the Astronomical Society of the Pacific
|year=2005
|volume=117|issue=828
|pages=121–131
|bibcode=2005PASP..117..121L
|doi=10.1086/428278|arxiv=astro-ph/0412487|s2cid=17585230
}}</ref>

<ref name=telegram1>{{Cite web|url=http://www.astronomerstelegram.org/?read=10372|title = ATel #10372: Confirmation of AT 2017eaw, a Probable Supernova in NGC 6946}}</ref>

<ref name=telegram2>{{Cite web|url=http://www.astronomerstelegram.org/?read=10376|title = ATel #10376: Spectroscopic Classification of SN 2017eaw in NGC 6946 as a Young Type IIP Supernova}}</ref>

<ref name=list>{{cite web
|title=List of Supernovae |title=List of Supernovae
|publisher=Harvard-Smithsonian Center for Astrophysics (IAU) |publisher=Harvard-Smithsonian Center for Astrophysics (IAU)
|url=http://cbat.eps.harvard.edu/lists/Supernovae.html |url=http://cbat.eps.harvard.edu/lists/Supernovae.html
|access-date=2010-07-12}}</ref>
|accessdate=2010-07-12}}</ref> This makes it the most prolific known galaxy for this type of event over a period of 100 years. By comparison, the ] galaxy, which has double the number of stars as NGC 6946, averages one supernova event per century.<ref>{{citation

<ref name=gemini>{{Cite news|url=http://www.gemini.edu/node/116
|title=Gemini Observatory Welcomes 2005 with Release of Galactic Fireworks Image
|last=Michaud|first=Peter
|date=1 January 2015
|newspaper=NASA
|access-date=2017-10-15}}</ref>

<ref name=fireworks>{{Cite news|url=https://www.nasa.gov/mission_pages/chandra/multimedia/fireworks-galaxy-ngc6946.html
|title=NGC 6946: The 'Fireworks Galaxy'
|last=Boen|first=Brooke
|date=20 May 2015
|newspaper=NASA
|access-date=2016-12-08}}</ref>

<ref name=gemini2005>{{citation
|title=Gemini Observatory Welcomes 2005 with Release of Galactic Fireworks Image |title=Gemini Observatory Welcomes 2005 with Release of Galactic Fireworks Image
|date=1 January 2005 |date=1 January 2005
|work=Gemini Observatory |work=Gemini Observatory
|url=http://www.gemini.edu/node/116 |url=http://www.gemini.edu/node/116
|accessdate=2016-01-04 | postscript=.}}</ref> |access-date=2016-01-04}}</ref>

It also contains a ], potential black hole-forming star ].<ref name=adams>{{cite journal
<ref name="Adams2016">{{cite journal
|last1=Adams|first1=S. M. |last1=Adams|first1=S. M.
|last2=Kochanek|first2=C. S. |last2=Kochanek|first2=C. S.
Line 50: Line 173:
|last5=Dai|first5=X. |last5=Dai|first5=X.
|title=The search for failed supernovae with the Large Binocular Telescope: conformation of a disappearing star |title=The search for failed supernovae with the Large Binocular Telescope: conformation of a disappearing star
|year=2017
|date=9 September 2016
|journal=Monthly Notices of the Royal Astronomical Society
|arxiv=1609.01283v1}}</ref>
|volume=468
|issue=4
|pages=4968–4981
|doi=10.1093/mnras/stx816
|doi-access=free
|arxiv=1609.01283v1|bibcode=2017MNRAS.468.4968A|s2cid=12919545
}}</ref>


<ref name="SEDS2013">{{cite web
==References==
|title=NGC 6946
{{Reflist}}
|publisher=SEDS
|url=http://www.messier.seds.org/xtra/ngc/n6946.html
|access-date=2017-11-20}}</ref>

<ref name=KF18>{{cite journal
| last1 = Kilpatrick
| first1 = Charles
| last2 = Foley
| first2 = Ryan
| title = The Dusty Progenitor Star of the Type II Supernova 2017eaw
| date = 5 September 2018
| journal = Monthly Notices of the Royal Astronomical Society
| volume = 481
| issue = 2
| pages = 2536–2547
| doi = 10.1093/mnras/sty2435| doi-access = free
| arxiv = 1806.00348
}}</ref>

}}


==External links== ==External links==
{{commons category}}
* *
*
* *
* Giant Star Becomes A Black Hole Right Before Our Eyes! * Giant Star Becomes A Black Hole Right Before Our Eyes!
* {{WikiSky}} * {{WikiSky}}
*


{{Astronomical catalogs|Arp=29|NGC=6946|C=12|UGC=11597|PGC=65001}}
{{Caldwell catalogue}}
{{NGC objects:6500-6999}}
{{Cygnus (constellation)}}
{{Portal bar|Astronomy|Stars|Outer space}}
{{Sky|20|34|52.3|+|60|09|14|18000000}} {{Sky|20|34|52.3|+|60|09|14|18000000}}

{{Astronomical catalogs|Arp=29|NGC=6946|C=12|UGC=11597|PGC=65001}}


{{DEFAULTSORT:Ngc 6946}} {{DEFAULTSORT:Ngc 6946}}
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] ]
] ]
]

Latest revision as of 18:26, 25 October 2024

Galaxy in the constellations Cepheus & Cygnus
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NGC 6946
A image of NGC 6946, the fireworks galaxy.
Observation data (J2000 epoch)
ConstellationCepheus & Cygnus
Right ascension20 34 52.3
Declination+60° 09′ 14″
Redshift0.000133
Heliocentric radial velocity48 ± 2 km/s
Distance25.2 ± 1.0 Mly
7.72± 0.32 Mpc)
Apparent magnitude (V)+9.6
Characteristics
TypeSAB(rs)cd
Size26.77 kpc (87,300 ly)
(diameter; 25.0 mag/arcsec B-band isophote)
Apparent size (V)16.0 x 11.2 arcmin
Other designations
UGC 11597, PGC 65001, Arp 29, Caldwell 12

NGC 6946, sometimes referred to as the Fireworks Galaxy, is a face-on intermediate spiral galaxy with a small bright nucleus, whose location in the sky straddles the boundary between the northern constellations of Cepheus and Cygnus. Its distance from Earth is about 25.2 million light-years or 7.72 megaparsecs, similar to the distance of M101 (NGC 5457) in the constellation Ursa Major. Both were once considered to be part of the Local Group, but are now known to be among the dozen bright spiral galaxies near the Milky Way but beyond the confines of the Local Group. NGC 6946 lies within the Virgo Supercluster.

The galaxy was discovered by William Herschel on 9 September 1798. Based on an estimation by the Third Reference Catalogue of Bright Galaxies (RC3) in 1991, the galaxy has a D25 B-band isophotal diameter of 26.77 kiloparsecs (87,300 light-years). It is heavily obscured by interstellar matter due to its location close to the galactic plane of the Milky Way. Due to its prodigious star formation it has been classified as an active starburst galaxy. NGC 6946 has also been classified as a double-barred spiral galaxy, with the inner, smaller bar presumably responsible for funneling gas into its center.

Various unusual celestial objects have been observed within NGC 6946. This includes the so-called 'Red Ellipse' along one of the northern arms that looks like a super-bubble or very large supernova remnant, and which may have been formed by an open cluster containing massive stars. There are also two regions of unusual dark lanes of nebulosity, while within the spiral arms several regions appear devoid of stars and gaseous hydrogen, some spanning up to two kiloparsecs across. A third peculiar object, discovered in 1967, is now known as "Hodge's Complex". This was once thought to be a young supergiant cluster, but in 2017 it was conjectured to be an interacting dwarf galaxy superimposed on NGC 6946.

Supernovae

Ten supernovae have been observed in NGC 6946 in the 20th and early 21st century: SN 1917A, SN 1939C, SN 1948B, SN 1968D, SN 1969P, SN 1980K, SN 2002hh, SN 2004et, SN 2008S, and SN 2017eaw. For this reason, NGC 6946 has sometimes been referred to as the "Fireworks Galaxy". This is about ten times the rate observed in our Milky Way galaxy, even though the Milky Way has twice as many stars as NGC 6946.

On 27 September 2004, the Type II supernova SN 2004et was observed at magnitude 15.2 and rose to a maximum visual magnitude of 12.7. Images taken during the preceding days revealed that the supernova explosion occurred on 22 September. The progenitor of the supernova was identified on earlier images –– only the seventh time that such an event was directly identified with its host star. The red supergiant progenitor had an initial mass of about 15M☉ in an interacting binary system shared with a blue supergiant.

During 2009, a bright star within NGC 6946 flared up over several months to become over one million times as bright as the Sun. Shortly thereafter it faded rapidly. Observations with the Hubble Space Telescope suggest that the star did not survive, although there remains some infrared emission from its position. This is thought to come from debris falling onto a black hole that formed when the star died. This potential black hole-forming star is designated N6946-BH1. The progenitor is believed to have been a yellow hypergiant star.

In May 2017, supernova SN 2017eaw was detected in the northwest region of the galaxy, and light curves obtained over the next 600 days showed that it was a Type II-P. The progenitor was determined to have been a red supergiant, with a mass of around 15M☉.

As of 2017, more supernovae had been seen in NGC 6946 than in any other galaxy, a record that has since been surpassed by NGC 3690.

Supernovae in NGC 6946
Supernova apmag type
2017eaw 12.6 IIP
2008S 16.5 IIn-pec/LBV
2004et 12.3 II
2002hh 15.0 II
1980K 11.4 IIL
1969P 13.9 ?
1968D 13.5 II
1948B 14.9 II
1939C 13.0 ?
1917A 14.6 II

Gallery

See also

References

  1. ^ "NASA/IPAC Extragalactic Database". Results for NGC 6946. Retrieved 29 October 2022.
  2. ^ Eldridge, J J; Xiao, Lin (2 March 2019). "The distance, supernova rate, and supernova progenitors of NGC 6946". Monthly Notices of the Royal Astronomical Society: Letters. 485 (1): L58–L61. arXiv:1903.00173. Bibcode:2019MNRAS.485L..58E. doi:10.1093/mnrasl/slz030. S2CID 118831398.
  3. ^ De Vaucouleurs, Gerard; De Vaucouleurs, Antoinette; Corwin, Herold G.; Buta, Ronald J.; Paturel, Georges; Fouque, Pascal (1991). Third Reference Catalogue of Bright Galaxies. Bibcode:1991rc3..book.....D.
  4. Jarrett, T. H.; Chester, T.; Cutri, R.; Schneider, S. E.; Huchra, J. P. (2003). "The 2MASS Large Galaxy Atlas". The Astronomical Journal. 125 (2): 525–554. Bibcode:2003AJ....125..525J. doi:10.1086/345794. S2CID 117784410.
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  8. "Nearby Groups of Galaxies". ned.ipac.caltech.edu. Retrieved 3 May 2018.
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  10. Schinnerer, Eva; et, al (2006). "Molecular Gas Dynamics in NGC 6946: A Bar-driven Nuclear Starburst Caught in the Act". The Astrophysical Journal. 649 (1): 181–200. arXiv:astro-ph/0605702. Bibcode:2006ApJ...649..181S. doi:10.1086/506265. S2CID 14717998.
  11. Eibensteiner, Cosima; et, al (2022). "A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946". Astronomy & Astrophysics. 659 (A173): 37. arXiv:2201.02209. Bibcode:2022A&A...659A.173E. doi:10.1051/0004-6361/202142624.
  12. Hodge, P.W. (1967). "A Possible "Super-Supernova" Remnant in NGC 6946". Open Astronomy. 79 (466): 466–470. Bibcode:1967PASP...79...29H. doi:10.1515/astro-2017-0255.
  13. ^ Li, W.; Van Dyk, S.D.; Filippenko, A.V; Cuillandre, J.C. (2005). "On the Progenitor of the Type II Supernova 2004et in NGC 6946". Publications of the Astronomical Society of the Pacific. 117 (828): 121–131. arXiv:astro-ph/0412487. Bibcode:2005PASP..117..121L. doi:10.1086/428278. S2CID 17585230.
  14. ^ Bishop, David (14 May 2017). "Supernova 2017eaw in NGC 6946". Retrieved 29 September 2023. This is our most prolific galaxy with now 10 confirmed supernovae discovered.
  15. "ATel #10372: Confirmation of AT 2017eaw, a Probable Supernova in NGC 6946".
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  18. Michaud, Peter (1 January 2015). "Gemini Observatory Welcomes 2005 with Release of Galactic Fireworks Image". NASA. Retrieved 15 October 2017.
  19. Boen, Brooke (20 May 2015). "NGC 6946: The 'Fireworks Galaxy'". NASA. Retrieved 8 December 2016.
  20. "Gemini Observatory Welcomes 2005 with Release of Galactic Fireworks Image", Gemini Observatory, 1 January 2005, retrieved 4 January 2016
  21. Adams, S. M.; Kochanek, C. S.; Gerke, J. R.; Stanek, K. Z.; Dai, X. (2017). "The search for failed supernovae with the Large Binocular Telescope: conformation of a disappearing star". Monthly Notices of the Royal Astronomical Society. 468 (4): 4968–4981. arXiv:1609.01283v1. Bibcode:2017MNRAS.468.4968A. doi:10.1093/mnras/stx816. S2CID 12919545.
  22. Humphreys, Roberta M. (31 October 2019). "Comments on the Progenitor of NGC 6946-BH1". Research Notes of the AAS. 3 (10): 164. arXiv:1911.02037. Bibcode:2019RNAAS...3..164H. doi:10.3847/2515-5172/ab5191. ISSN 2515-5172. S2CID 207880492.
  23. Buta, Ronald J; Keel, William C (21 July 2019). "BVRI photometry of the classic Type II-P supernova 2017eaw in NGC 6946: d 3 to d 594". Monthly Notices of the Royal Astronomical Society. 487 (1): 832–844. arXiv:1905.03084. Bibcode:2019MNRAS.487..832B. doi:10.1093/mnras/stz1291. ISSN 0035-8711. S2CID 147703978.
  24. Szalai, Tamás; Vinkó, József; Könyves-Tóth, Réka; Nagy, Andrea P.; Bostroem, K. Azalee; Sárneczky, Krisztián; Brown, Peter J.; Pejcha, Ondrej; Bódi, Attila; Cseh, Borbála; Csörnyei, Géza (29 April 2019). "The Type II-P Supernova 2017eaw: From Explosion to the Nebular Phase". The Astrophysical Journal. 876 (1): 19. arXiv:1903.09048. Bibcode:2019ApJ...876...19S. doi:10.3847/1538-4357/ab12d0. ISSN 1538-4357. S2CID 84842034.
  25. Kilpatrick, Charles; Foley, Ryan (5 September 2018). "The Dusty Progenitor Star of the Type II Supernova 2017eaw". Monthly Notices of the Royal Astronomical Society. 481 (2): 2536–2547. arXiv:1806.00348. doi:10.1093/mnras/sty2435.
  26. Bishop, David (27 August 2023). "The most prolific galaxies". Retrieved 29 September 2023.

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