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{{short description|Elliptical galaxy in the constellation Andromeda}} |
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{{short description|Dwarf elliptical galaxy in the constellation Andromeda}} |
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{{Infobox Galaxy |
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{{Infobox Galaxy |
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| name = ] 32 |
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| name = ] 32 |
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| image = ] |
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| image = ] |
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| caption = Dwarf Satellite Galaxy Messier 32 |
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| caption = Dwarf Satellite Galaxy Messier 32 (center) |
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| epoch = ] |
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| epoch = ] |
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| type = cE2<ref name="ned"> |
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| type = cE2<ref name="ned"> |
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| ra = {{RA|00|42|41.8}}<ref name="ned" /> |
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| ra = {{RA|00|42|41.8}}<ref name="ned" /> |
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| dec = {{DEC|+40|51|55}}<ref name="ned" /> |
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| dec = {{DEC|+40|51|55}}<ref name="ned" /> |
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| dist_ly = ] million ]s (763 ± 24 ])<ref name="jensenetal2003" /><ref name="karachentsevetal2004" /><ref name="Karachentsevetal2006" />{{Ref_label|A|a|none}} |
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| dist_ly = ] ] (763 ± 24 ])<ref name="jensenetal2003" /><ref name="karachentsevetal2004" /><ref name="Karachentsevetal2006" /> |
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| z = -200 ± 6 ]/]<ref name="ned" /> |
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| z = −200 ± 6 ]/]<ref name="ned" /> |
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| appmag_v = 8.08<ref name="SIMBAD-M32">{{cite simbad |
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| appmag_v = 8.08<ref name="SIMBAD-M32">{{cite simbad |
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|title=M32 |
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|title=M32 |
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|first9=Luciana |
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|first9=Luciana |
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|last10=Rey |
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|last10=Rey |
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|first10=Soo‐Chang |
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|first10=Soo-Chang |
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|last11=Rich |
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|last11=Rich |
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|first11=R. Michael |
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|first11=R. Michael |
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|s2cid=119085482 |
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|s2cid=119085482 |
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}}</ref> |
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}}</ref> |
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| size_v = 8′.7 × 6′.5<ref name="ned" /> |
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| size_v = 8.7' × 6.5'<ref name="ned" /> |
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| constellation name = ] |
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| constellation name = ] |
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| notes = ] of the<br>] |
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| notes = ] of the<br>] |
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'''Messier 32''' (also known as '''M32''' and '''NGC 221''') is a dwarf "early-type" galaxy about {{convert|2,650,000|ly|pc}} from our star system, appearing in the ] ]. M32 is a ] of the ] (M31) and was discovered by ] in 1749. Its true size is about {{frac|3|4}} of the radius of the Sun from the local galactic centre, {{convert|6300|-|6700|ly|pc}} at its quite unpronounced widest.<ref>Diameter = distance × sin(diameter_angle) = 6.5 ± 0.2 thousand light-years. diameter</ref> |
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'''Messier 32''' (also known as '''M32''' and '''NGC 221''') is a dwarf "early-type" galaxy about {{convert|2,490,000|ly|pc|lk=out}} from the ], appearing in the ] ]. M32 is a ] of the ] (M31) and was discovered by ] in 1749. |
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The galaxy is a prototype of the relatively rare, compact elliptical (cE) class. |
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The galaxy is a prototype of the relatively rare compact elliptical (cE) class. Half the stars concentrate within inner core with an ] of {{convert|330|ly|pc}}.<ref name="kent1987"> |
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Half the stars concentrate within an ] (inner core) of {{convert|330|ly|pc}}.<ref name="kent1987"> |
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{{cite journal |
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{{cite journal |
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|author1=Kent, S. M. |
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|author1=Kent, S. M. |
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|bibcode=1987AJ.....94..306K |
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|bibcode=1987AJ.....94..306K |
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|doi=10.1086/114472 |
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|doi=10.1086/114472 |
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|doi-access=free |
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}} |
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}} |
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</ref><ref name="mateo1998">{{cite journal |
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</ref><ref name="mateo1998">{{cite journal |
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|author1=Mateo, M. L. |
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|author1=Mateo, M. L. |
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|s2cid=119333888 |
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|s2cid=119333888 |
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}} |
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}} |
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⚫ |
</ref> Densities in the central stellar cusp increase steeply, exceeding 3×10<sup>7</sup> (that is, 30 million) {{solar mass|link=yes}} pc<sup>−3</sup> (that is, per parsec cubed) at the smallest sub-radii resolved by ],<ref name="lauer1992"> |
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</ref> |
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Densities in the central stellar cusp increase steeply, exceeding 3×10<sup>7</sup> (that is, 30 million) {{solar mass|link=yes}} pc<sup>−3</sup> (that is, per parsec cubed) at the smallest sub-radii resolved by ],<ref name="lauer1992"> |
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{{cite journal |
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{{cite journal |
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|author1=Lauer, T. R. |
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|author1=Lauer, T. R. |
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|url=https://authors.library.caltech.edu/52363/1/1992AJ____104__552L.pdf |
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|url=https://authors.library.caltech.edu/52363/1/1992AJ____104__552L.pdf |
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}} |
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}} |
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</ref> and the half-light radius of this central star cluster is around {{convert|6|pc}}.<ref>Graham, A.W. and Spitler, L.R., </ref> |
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</ref> and the half-light radius of this central star cluster is around {{convert|6|pc|ly|abbr=in}}.<ref>Graham, A.W. and Spitler, L.R., .</ref> Like more ordinary ], M32 contains mostly old faint red and yellow stars with practically no dust or gas and consequently no current ].<ref name="NSOG"> |
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Like more ordinary ], M32 contains mostly older faint red and yellow stars with practically no dust or gas and consequently no current ].<ref name="NSOG"> |
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{{cite book |
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{{cite book |
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|last=Kepple |first=George Robert |
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|last=Kepple |first=George Robert |
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|date=1998 |
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|date=1998 |
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|title=The Night Sky Observer's Guide |
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|title=The Night Sky Observer's Guide |
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|volume=Vol. 1 |page=17 |
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|volume=1 |page=17 |
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|publisher=] |
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|publisher=] |
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|isbn=978-0-943396-58-3 |
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|isbn=978-0-943396-58-3 |
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|doi-access=free |
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|doi-access=free |
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}}</ref> |
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}}</ref> |
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] |
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] |
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==Origins== |
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==Origins== |
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] |
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The structure and stellar content of M32 are difficult to explain by traditional ] models. |
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The structure and stellar content of M32 are difficult to explain by traditional ] models. |
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Theoretical arguments<ref name="faber1973"> |
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Theoretical arguments<ref name="faber1973"> |
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and as such is not a typical elliptical galaxy. |
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and as such is not a typical elliptical galaxy. |
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Newer simulations find that an off-centre |
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Newer simulations find that an off-centre ] |
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] |
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around 800 million years ago explains the present-day ] in M31's disk.<ref name="Dierickx2014"> |
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around 800 million years ago explains the present-day ] in M31's disk.<ref name="Dierickx2014"> |
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{{cite journal |
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{{cite journal |
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|author2=Blecha, L. |
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|author2=Blecha, L. |
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|author3=Loeb, A. |
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|author3=Loeb, A. |
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|title=Signatures of the M31-M32 Galactic Collision |
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|title=Signatures of the M31–M32 Galactic Collision |
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|journal=] |
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|journal=] |
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|volume=788 |
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|volume=788 |
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|pages=1956–1960 |
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|pages=1956–1960 |
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|doi=10.1093/mnras/stt014 |
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|doi=10.1093/mnras/stt014 |
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|bibcode=2013MNRAS.430.1956H |
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|doi-access=free |
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|bibcode=2013MNRAS.430.1956H |
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|arxiv=1302.6520 |
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|arxiv=1302.6520 |
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|s2cid=119291374 |
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|s2cid=119291374 |
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}}</ref> |
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}}</ref> |
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Another hypothesis is that M32 would be in fact the largest remnant of a former spiral galaxy, ], which was then the third largest member of the Local Group.<ref>{{Cite news|url=https://news.umich.edu/the-milky-ways-long-lost-sibling-finally-found/|title=The Milky Way's long-lost sibling finally found|date=2018-07-23|work=University of Michigan News|access-date=2018-07-23|language=en-US}}</ref> According to this simulation, M31 (Andromeda) and M32p merged about two billion years ago, which could explain both the unusual makeup of the current M31 stellar halo, and the structure and content of M32.<ref name="10.1038/s41550-018-0533-x">{{Cite journal|last1=D’Souza|first1=Richard|last2=Bell|first2=Eric F.|date=2018-07-23|title=The Andromeda galaxy's most important merger about 2 billion years ago as M32's likely progenitor|journal=Nature Astronomy|volume=2|issue=9|pages=737–743|language=En|doi=10.1038/s41550-018-0533-x|issn=2397-3366|arxiv=1807.08819|bibcode=2018NatAs...2..737D|s2cid=119502746}}</ref> |
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Another hypothesis is that M32 is in fact the largest remnant of a former spiral galaxy, ], which was then the third largest member of the Local Group.<ref>{{Cite news|url=https://news.umich.edu/the-milky-ways-long-lost-sibling-finally-found/|title=The Milky Way's long-lost sibling finally found|date=2018-07-23|work=University of Michigan News|access-date=2018-07-23|language=en-US}}</ref> According to this simulation, M31 (Andromeda) and M32p merged about two billion years ago, which could explain both the unusual makeup of the current M31 stellar halo, and the structure and content of M32.<ref name="10.1038/s41550-018-0533-x">{{Cite journal|last1=D’Souza|first1=Richard|last2=Bell|first2=Eric F.|date=2018-07-23|title=The Andromeda galaxy's most important merger about 2 billion years ago as M32's likely progenitor|journal=Nature Astronomy|volume=2|issue=9|pages=737–743|language=En|doi=10.1038/s41550-018-0533-x|issn=2397-3366|arxiv=1807.08819|bibcode=2018NatAs...2..737D|s2cid=119502746}}</ref> |
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==Distance measurements== |
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==Distance measurements== |
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|author2=Jacoby, G. H. |
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|author2=Jacoby, G. H. |
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|author3=Jenner, D. C. |
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|author3=Jenner, D. C. |
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|title=Planetary nebulae in local group galaxies. VI - an observational determination that M32 is in front of M31 |
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|title=Planetary nebulae in local group galaxies. VI – an observational determination that M32 is in front of M31 |
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|journal=] |
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|journal=] |
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|volume=223 |
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|volume=223 |
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|doi=10.1086/156239 |
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|doi=10.1086/156239 |
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|bibcode=1978ApJ...223...94F |
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|bibcode=1978ApJ...223...94F |
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|doi-access=free |
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}}</ref><ref name="van_dokkum1995">{{cite journal |
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}}</ref><ref name="van_dokkum1995">{{cite journal |
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|author1=van Dokkum, P. G. |
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|author1=van Dokkum, P. G. |
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|author2=Franx, M. |
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|author2=Franx, M. |
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|s2cid=118939047 |
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|s2cid=118939047 |
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}}</ref> |
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}}</ref> |
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] of M31 by a star in M32 was observed{{when?|date=January 2021}} in one event{{what?|date=January 2021}}.<ref name="paulin-henriksson2002">{{cite journal |
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] of M31 by a star in M32 was observed at the end of November 2000 in one event (with peak on 2 December 2000).<ref name="paulin-henriksson2002">{{cite journal |
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|author1=Paulin-Henriksson, S. |
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|author1=Paulin-Henriksson, S. |
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|author2=Baillon, P. |
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|author2=Baillon, P. |
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==Black hole== |
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==Black hole== |
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M32 contains a ]. |
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M32 contains a ]. |
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Its mass has been estimated to lie between 1.5 and 5 million solar masses.<ref name="tonry1984"> |
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Its mass has been estimated to lie between 1.5 and 5 million solar masses.<ref name="tonry1984"> |
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|author2=Kormendy, J. |
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|author2=Kormendy, J. |
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|author3=Dehnen, W. |
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|author3=Dehnen, W. |
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|title=Improved Evidence for a 3×10<sup>6</sup> M<sub>⊙</sub> Black Hole in M32: Canada-France-Hawaii Telescope Spectroscopy with FWHM = 0.47" Resolution |
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|title=Improved Evidence for a 3×10<sup>6</sup> M<sub>⊙</sub> Black Hole in M32: Canada–France–Hawaii Telescope Spectroscopy with FWHM = 0.47" Resolution |
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|journal=] |
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|journal=] |
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|volume=464 |
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|volume=464 |
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|pages=517–525 |
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|pages=517–525 |
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|doi=10.1111/j.1365-2966.2009.15832.x |
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|doi=10.1111/j.1365-2966.2009.15832.x |
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|bibcode=2002MNRAS.335..517V |
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|doi-access=free |
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|bibcode=2002MNRAS.335..517V |
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|arxiv=astro-ph/0201086 |
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|arxiv=astro-ph/0201086 |
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|s2cid=119238097 |
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|s2cid=119238097 |
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|pages=1770–1780 |
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|pages=1770–1780 |
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|doi=10.1111/j.1365-2966.2009.15832.x |
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|doi=10.1111/j.1365-2966.2009.15832.x |
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|bibcode=2010MNRAS.401.1770V |
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|doi-access=free |
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|bibcode=2010MNRAS.401.1770V |
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|arxiv=0910.0844 |
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|arxiv=0910.0844 |
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|s2cid=119238097 |
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|s2cid=119238097 |
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==See also== |
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==See also== |
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* ] |
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* ] |
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* ] |
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* ] |
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* ] |
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{{commons category|Messier 32}} |
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{{commons category|Messier 32}} |
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* {{cite web|last=Merrifield|first=Michael|title=M32 – Dwarf Elliptical|url=http://www.deepskyvideos.com/videos/messier/M32_dwarf_elliptical_galaxy.html|work=Deep Sky Videos|publisher=]}} |
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* {{cite web|last=Merrifield|first=Michael|title=M32 – Dwarf Elliptical|url=http://www.deepskyvideos.com/videos/messier/M32_dwarf_elliptical_galaxy.html|work=Deep Sky Videos|publisher=]}}{{WikiSky}} |
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* {{WikiSky}} |
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{{Andromeda galaxy}} |
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{{Andromeda galaxy}} |
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{{Messier objects}} |
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{{Messier objects}} |
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{{Ngc5}} |
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{{Ngc5}} |
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{{Portal bar|Astronomy|Stars|Outer space}} |
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{{Sky|00|42|41.8||40|51|55|2490000}} |
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{{Sky|00|42|41.8||40|51|55|2490000}} |
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The galaxy is a prototype of the relatively rare compact elliptical (cE) class. Half the stars concentrate within inner core with an effective radius of 330 light-years (100 pc). Densities in the central stellar cusp increase steeply, exceeding 3×10 (that is, 30 million) M☉ pc (that is, per parsec cubed) at the smallest sub-radii resolved by HST, and the half-light radius of this central star cluster is around 6 pc (20 light-years). Like more ordinary elliptical galaxies, M32 contains mostly old faint red and yellow stars with practically no dust or gas and consequently no current star formation. It does, however, show hints of star formation in the relatively recent past.
The structure and stellar content of M32 are difficult to explain by traditional galaxy formation models.
Theoretical arguments
and some simulations suggest a scenario in which the strong tidal field of M31 can transform a spiral galaxy or a lenticular galaxy into a compact elliptical. As a small disk galaxy falls into the central parts of M31, much of its outer layers will be stripped away. The central bulge of the small galaxy is much less affected and retains its morphology. Gravitational tidal effects may also drive gas inward and trigger a star burst in the core of the small galaxy, resulting in the high density of M32 observed today.
There is evidence that M32 has a faint outer disk,
and as such is not a typical elliptical galaxy.
Another hypothesis is that M32 is in fact the largest remnant of a former spiral galaxy, M32p, which was then the third largest member of the Local Group. According to this simulation, M31 (Andromeda) and M32p merged about two billion years ago, which could explain both the unusual makeup of the current M31 stellar halo, and the structure and content of M32.
At least two techniques have been used to measure distances to M32. The infrared surface brightness fluctuations distance measurement technique estimates distances to spiral galaxies based on the graininess of the appearance of their bulges. The distance measured to M32 using this technique is 2.46 ± 0.09 million light-years (755 ± 28 kpc). However, M32 is close enough that the tip of the red giant branch (TRGB) method may be used to estimate its distance. The estimated distance to M32 using this technique is 2.51 ± 0.13 million light-years (770 ± 40 kpc).
For several additional reasons, M32 is thought to be in the foreground of M31, rather than behind.
Its stars and planetary nebulae do not appear obscured or reddened by foreground gas or dust.
Gravitational microlensing of M31 by a star in M32 was observed at the end of November 2000 in one event (with peak on 2 December 2000).
Dwarf Satellite Galaxy Messier 32 (center)
.jpg)
Category
