Sher 25

{{Short description|Star in the constellation Carina}}

{{Starbox begin

| name = Sher 25

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{{Starbox image

| image = 280px

| caption = HST image of Sher 25 its nebula. NGC 3603 is on the lower left.

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{{Starbox observe

| epoch = J2000.0

| equino = J2000.0

| constell = Carina

| pronounce =

| ra = {{RA|11|15|7.645}}

| dec = {{DEC|-61|15|17.61}}

| appmag_v = 12.23{{Cite journal | last1 = Melena | first1 = N. W. | last2 = Massey | first2 = P. | last3 = Morrell | first3 = N. I. |author-link3=Nidia Morrell | last4 = Zangari | first4 = A. M. | title = The Massive Star Content of Ngc 3603 | doi = 10.1088/0004-6256/135/3/878 | journal = The Astronomical Journal | volume = 135 | issue = 3 | pages = 878 | year = 2008 |arxiv = 0712.2621 |bibcode = 2008AJ....135..878M | s2cid = 16765414 }}

}}

{{Starbox character

| class = B1Iab

| appmag_1_passband =

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| appmag_3_passband =

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| appmag_6_passband =

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| r-i =

| v-r =

| b-v = 1.42

| u-b = 0.13

| j-h =

| j-k =

| variable = cLBV{{Cite journal | last1 = Smartt | first1 = S. J. | last2 = Lennon | first2 = D. J. | last3 = Kudritzki | first3 = R. P. | last4 = Rosales | first4 = F. | last5 = Ryans | first5 = R. S. I. | last6 = Wright | first6 = N. | year = 2002 | title = The evolutionary stat9us of Sher 25 - implications for blue supergiants and the progenitor of SN 1987A| journal = Astronomy and Astrophysics | volume = 391 | issue = 3 | pages = 979 | arxiv = astro-ph/0205242| bibcode = 2002A&A...391..979S| doi = 10.1051/0004-6361:20020829 | s2cid = 14933392 }}

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{{Starbox astrometry

| radial_v =

| prop_mo_ra = −5.387

| prop_mo_dec = +2.116

| parallax = 0.1560

| p_error = 0.0166

| parallax_footnote = {{cite Gaia DR3|5337418397799185536}}

| dist_ly = {{val|17700|2300|fmt=commas}}

| dist_pc = {{val|5440|700|fmt=commas}}

| dist_footnote =

| absmag_v = {{val|-7.05|0.34}}

}}

{{Starbox detail

| source = {{Cite journal |last=Weßmayer |first=D. |last2=Przybilla |first2=N. |last3=Ebenbichler |first3=A. |last4=Aschenbrenner |first4=P. |last5=Butler |first5=K. |date=2023-09-01 |title=The blue supergiant Sher 25 revisited in the Gaia era |url=https://ui.adsabs.harvard.edu/abs/2023A&A...677A.175W/abstract |journal=Astronomy and Astrophysics |volume=677 |pages=A175 |doi=10.1051/0004-6361/202347253 |bibcode=2023A&A...677A.175W |issn=0004-6361|arxiv=2308.06164 }}

| mass = {{val|25.5|1.7}}

| radius = {{val|42|7}}

| gravity = {{val|2.61|0.06}}

| luminosity =

| luminosity_bolometric = {{val|308000|115000|83000|fmt=commas}}

| luminosity_visual =

| temperature = {{val|20900|500|fmt=commas}}

| metal =

| rotation =

| rotational_velocity = {{val|60|5}}

| age_myr = {{val|7.24|0.70|0.64}}

}}

{{Starbox catalog

| names = Sher 25, NGC 3603-25, NGC 3603 MTT 13, NGC 3603 MDS 5

}}

{{Starbox reference

| Simbad = Sher+25

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{{Starbox end}}

Sher 25 is a blue supergiant star in the constellation Carina, located approximately 25,000 light years from the Sun in the H II region NGC 3603 of the Milky Way.{{cite journal|last1=Sher|first1=D.|title=Distances of Five Open Cluster Near Eta Carinae|journal=Monthly Notices of the Royal Astronomical Society|volume=129|issue=3|year=1965|pages=237–262|issn=0035-8711|doi=10.1093/mnras/129.3.237|bibcode=1965MNRAS.129..237S|doi-access=free}} It is a spectral type B1Iab star with an apparent magnitude of 12.2.{{cite journal

| author=Brandner, Wolfgang| author2=Grebel, Eva K.| author3=Chu, You-Hua| author4=Weis, Kerstin

| title=Ring Nebula and Bipolar Outflows Associated with the B1.5 Supergiant Sher 25 in NGC 3603

| journal=Astrophysical Journal Letters | volume=475 | page=L45

|date=January 1997

| issue=1| doi=10.1086/310460 | bibcode=1997ApJ...475L..45B |arxiv = astro-ph/9611046 | s2cid=18830644}} Its initial main sequence mass is calculated at 60 times the mass of the Sun, but a star of this type will have already lost a substantial fraction of that mass. It is unclear whether Sher 25 has been through a red supergiant phase or has just evolved from the main sequence, so the current mass is very uncertain.{{Cite journal | last1 = Hendry | first1 = M. A. | last2 = Smartt | first2 = S. J. | last3 = Skillman | first3 = E. D. | last4 = Evans | first4 = C. J. | last5 = Trundle | first5 = C. | last6 = Lennon | first6 = D. J. | last7 = Crowther | first7 = P. A. | last8 = Hunter | first8 = I. | doi = 10.1111/j.1365-2966.2008.13347.x | title = The blue supergiant Sher 25 and its intriguing hourglass nebula | journal = Monthly Notices of the Royal Astronomical Society | volume = 388 | issue = 3 | pages = 1127 | year = 2008 | doi-access = free |arxiv = 0803.4262 |bibcode = 2008MNRAS.388.1127H | s2cid = 16802111 }}

The name derives from the original cataloguing of stars in NGC 3603 by David Sher. This catalogue entry is more fully referred to as NGC 3603 Sher 25 to distinguish it from stars potentially numbered 25 by Sher in other clusters (eg. NGC 3766).{{cite journal |bibcode=1965MNRAS.129..237S |title=Distances of five open cluster near Eta Carinae |last1=Sher |first1=D. |journal=Monthly Notices of the Royal Astronomical Society |year=1965 |volume=129 |issue=3 |page=237 |doi=10.1093/mnras/129.3.237 |doi-access=free }} The same star was numbered 13 by Melnick, Tapia, and Terlevich{{cite journal|title=The galactic giant H II region NGC 3603|journal=Astronomy and Astrophysics|volume=213|pages=89|author1=Melnick, J. |author2=Tapia, M. |author3=Terlevich, R. |bibcode=1989A&A...213...89M|year=1989}} (MTT 13) and 5 in a Hubble Space Telescope survey by Moffat, Drissen, and Shara{{Cite journal | last1 = Moffat | first1 = A. F. J. | last2 = Drissen | first2 = L. | last3 = Shara | first3 = M. M. | title = NGC 3603 and its Wolf-Rayet stars: Galactic clone of R136 at the core of 30 Doradus, but without the massive surrounding cluster halo | doi = 10.1086/174891 | journal = The Astrophysical Journal | volume = 436 | pages = 183 | year = 1994 |bibcode = 1994ApJ...436..183M | doi-access = free }} (NGC 3603 MDS 5).

It is speculated that Sher 25 is near the point of exploding as a supernova, as it has recently thrown off matter in a pattern similar to that of supernova 1987A in the Large Magellanic Cloud, with a circumstellar ring and bipolar outflow filaments.

Regular variations in the doppler shift of the star's spectral lines with a period of a few days may be due to orbital motion about a companion star, or to pulsations of the star's surface.{{cite journal|last1=Taylor|first1=W. D.|last2=Evans|first2=C. J.|last3=Simon-Diaz|first3=S.|last4=Sana|first4=H.|last5=Langer|first5=N.|last6=Smith|first6=N.|last7=Smartt|first7=S. J.|title=Sher 25: pulsating but apparently alone|journal=Monthly Notices of the Royal Astronomical Society|volume=442|issue=2|year=2014|pages=1483–1490|issn=0035-8711|doi=10.1093/mnras/stu925|doi-access=free |bibcode=2014MNRAS.442.1483T|arxiv = 1405.2101 }}