“NGC 1817”的意思、由来-开放百科全书

The NGC 1817 cluster is around the same age as the Hyades, or perhaps a little younger at 0.8−1.2 billion years. The turnoff point for this cluster—where stars above a certain mass are evolving through the red giant stage—is twice the mass of the Sun.^[10] The cluster is situated in the opposite side of the sky from the Galactic Core at a separation of {{Convert|9.9|kpc|kly|abbr=on|lk=off|order=flip}} from the core,^[10] and is around {{Convert|0.4|kpc|kly|abbr=on|lk=off|order=flip}} away from the Galactic plane.^[6]

Measurements of the proper motion of 810 stars within a 1.5° region centered on the cluster suggest that it has at least 169 members.^[13] Of these, there is a total of 26 variable stars, including three candidate Gamma Doradus variable stars and sixteen Delta Scuti variables.^[14] This unusually high proportion of Delta Scuti variables is likely the result of the turnoff point being located within the instability strip.^[7]

References

1. ^¹{{cite journal | display-authors=1 | last1=Kharchenko | first1=N. V. | last2=Piskunov | first2=A. E. | last3=Röser | first3=S. | last4=Schilbach | first4=E. | last5=Scholz | first5=R.-D. | title=Astrophysical parameters of Galactic open clusters | journal=Astronomy and Astrophysics | volume=438 | issue=3 | pages=1163–1173 | date=August 2005 | doi=10.1051/0004-6361:20042523 | bibcode=2005A&A...438.1163K | arxiv = astro-ph/0501674 }}
2. ^¹²{{citation | display-authors=1 | last1=Donati | first1=P. | last2=Beccari | first2=G. | last3=Bragaglia | first3=A. | last4=Cignoni | first4=M. | last5=Tosi | first5=M. | title=NGC 1817, NGC 2141 and Berkeley 81: three BOCCE clusters of intermediate age | journal=Monthly Notices of the Royal Astronomical Society | volume=437 | issue=2 | pages=1241–1258 | date=January 2014 | doi=10.1093/mnras/stt1944 | bibcode=2014MNRAS.437.1241D | arxiv=1311.2469 | postscript=.}}
3. ^¹²³{{citation | first1=Jess K. | last1=Gilmour | title=The Practical Astronomer's Deep-sky Companion | series=The Patrick Moore Practical Astronomy Series | publisher=Springer Science & Business Media | year=2012 | isbn=978-1447100713 | page=123 | url=https://books.google.com/books?id=HyMRBwAAQBAJ&pg=PA111 | postscript=.}}
4. ^¹²{{citation | display-authors=1 | last1=Reddy | first1=Arumalla B. S. | last2=Giridhar | first2=Sunetra | last3=Lambert | first3=David L. | title=Comprehensive abundance analysis of red giants in the open clusters NGC 752, 1817, 2360 and 2506 | journal=Monthly Notices of the Royal Astronomical Society | volume=419 | issue=2 | pages=1350–1361 | date=January 2012 | doi=10.1111/j.1365-2966.2011.19791.x | bibcode=2012MNRAS.419.1350R | postscript=.|arxiv = 1109.2678 }}
5. ^¹{{citation | display-authors=1 | last1=Andersen | first1=M. F. | last2=Arentoft | first2=T. | last3=Frandsen | first3=S. | last4=Glowienka | first4=L. | last5=Jensen | first5=H. R. | last6=Grundahl | first6=F. | title=NGC 1817: the richest population of delta Scuti stars | journal=Communications in Asteroseismology | volume=160 | page=9 | date=July 2009 | bibcode=2009CoAst.160....9A | postscript=. | doi=10.1553/cia160s9}}
6. ^¹{{citation | last1=Balaguer-Núñez | first1=L. | last2=Jordi | first2=C. | last3=Galadí-Enríquez | first3=D. | last4=Zhao | first4=J. L. | journal=Astronomy and Astrophysics | title=New membership determination and proper motions of NGC 1817. Parametric and non-parametric approach | volume=426 | issue=3 | pages=819–826 | date=November 2004 | doi=10.1051/0004-6361:20041332 | bibcode=2004A&A...426..819B | arxiv=astro-ph/0407455 | postscript=.}}
7. ^¹²³{{citation | first1=Stephen James | last1=O'Meara | title=Deep-Sky Companions: The Secret Deep | volume=4 | publisher=Cambridge University Press | year=2011 | page=84 | isbn=978-1139500074 | url=https://books.google.com/books?id=v859bKO0A4gC&pg=PA94 | postscript=.}}

词条	NGC 1817
释义	References {{Infobox cluster \| name = NGC 1817 \| image = File:NGC 1817 DSS.jpg \| caption = NGC 1817 as seen by the DSS \| credit = \| type = Open Cluster \| epoch = J2000 \| constellation = Taurus \| ra = {{RA\|05\|12\|15.(0)}} \| dec = {{DEC\|+16\|41\|2(4)}} \| dist_ly = {{Convert\|1972\|pc\|ly\|abbr=on\|lk=on\|order=flip}}^[3] \| dist_pc = \| appmag_v = 7.0^[4] \| size_v = 17.0′^[4] \| mass_msol = \| age = 0.8−1.2^[6] Gyr \| notes = \| names = C 0509+166, Collinder 60 }}NGC 1817 is an open cluster of stars in the constellation Taurus. It was discovered by English astronomer William Herschel in February 1784.^[7] With an apparent magnitude of 7 and spanning 17 arc minutes across the sky, it is separated from the NGC 1807 cluster by just a few degrees.^[4] Indeed, the two may actually be parts of a single extended cluster.^[7] The NGC 1817 cluster is around the same age as the Hyades, or perhaps a little younger at 0.8−1.2 billion years. The turnoff point for this cluster—where stars above a certain mass are evolving through the red giant stage—is twice the mass of the Sun.^[10] The cluster is situated in the opposite side of the sky from the Galactic Core at a separation of {{Convert\|9.9\|kpc\|kly\|abbr=on\|lk=off\|order=flip}} from the core,^[10] and is around {{Convert\|0.4\|kpc\|kly\|abbr=on\|lk=off\|order=flip}} away from the Galactic plane.^[6] Measurements of the proper motion of 810 stars within a 1.5° region centered on the cluster suggest that it has at least 169 members.^[13] Of these, there is a total of 26 variable stars, including three candidate Gamma Doradus variable stars and sixteen Delta Scuti variables.^[14] This unusually high proportion of Delta Scuti variables is likely the result of the turnoff point being located within the instability strip.^[7] References 1. ^¹{{cite journal \| display-authors=1 \| last1=Kharchenko \| first1=N. V. \| last2=Piskunov \| first2=A. E. \| last3=Röser \| first3=S. \| last4=Schilbach \| first4=E. \| last5=Scholz \| first5=R.-D. \| title=Astrophysical parameters of Galactic open clusters \| journal=Astronomy and Astrophysics \| volume=438 \| issue=3 \| pages=1163–1173 \| date=August 2005 \| doi=10.1051/0004-6361:20042523 \| bibcode=2005A&A...438.1163K \| arxiv = astro-ph/0501674 }} 2. ^¹²{{citation \| display-authors=1 \| last1=Donati \| first1=P. \| last2=Beccari \| first2=G. \| last3=Bragaglia \| first3=A. \| last4=Cignoni \| first4=M. \| last5=Tosi \| first5=M. \| title=NGC 1817, NGC 2141 and Berkeley 81: three BOCCE clusters of intermediate age \| journal=Monthly Notices of the Royal Astronomical Society \| volume=437 \| issue=2 \| pages=1241–1258 \| date=January 2014 \| doi=10.1093/mnras/stt1944 \| bibcode=2014MNRAS.437.1241D \| arxiv=1311.2469 \| postscript=.}} 3. ^¹²³{{citation \| first1=Jess K. \| last1=Gilmour \| title=The Practical Astronomer's Deep-sky Companion \| series=The Patrick Moore Practical Astronomy Series \| publisher=Springer Science & Business Media \| year=2012 \| isbn=978-1447100713 \| page=123 \| url=https://books.google.com/books?id=HyMRBwAAQBAJ&pg=PA111 \| postscript=.}} 4. ^¹²{{citation \| display-authors=1 \| last1=Reddy \| first1=Arumalla B. S. \| last2=Giridhar \| first2=Sunetra \| last3=Lambert \| first3=David L. \| title=Comprehensive abundance analysis of red giants in the open clusters NGC 752, 1817, 2360 and 2506 \| journal=Monthly Notices of the Royal Astronomical Society \| volume=419 \| issue=2 \| pages=1350–1361 \| date=January 2012 \| doi=10.1111/j.1365-2966.2011.19791.x \| bibcode=2012MNRAS.419.1350R \| postscript=.\|arxiv = 1109.2678 }} 5. ^¹{{citation \| display-authors=1 \| last1=Andersen \| first1=M. F. \| last2=Arentoft \| first2=T. \| last3=Frandsen \| first3=S. \| last4=Glowienka \| first4=L. \| last5=Jensen \| first5=H. R. \| last6=Grundahl \| first6=F. \| title=NGC 1817: the richest population of delta Scuti stars \| journal=Communications in Asteroseismology \| volume=160 \| page=9 \| date=July 2009 \| bibcode=2009CoAst.160....9A \| postscript=. \| doi=10.1553/cia160s9}} 6. ^¹{{citation \| last1=Balaguer-Núñez \| first1=L. \| last2=Jordi \| first2=C. \| last3=Galadí-Enríquez \| first3=D. \| last4=Zhao \| first4=J. L. \| journal=Astronomy and Astrophysics \| title=New membership determination and proper motions of NGC 1817. Parametric and non-parametric approach \| volume=426 \| issue=3 \| pages=819–826 \| date=November 2004 \| doi=10.1051/0004-6361:20041332 \| bibcode=2004A&A...426..819B \| arxiv=astro-ph/0407455 \| postscript=.}} 7. ^¹²³{{citation \| first1=Stephen James \| last1=O'Meara \| title=Deep-Sky Companions: The Secret Deep \| volume=4 \| publisher=Cambridge University Press \| year=2011 \| page=84 \| isbn=978-1139500074 \| url=https://books.google.com/books?id=v859bKO0A4gC&pg=PA94 \| postscript=.}} ^[1]^[2]^[3]^[4]^[5]^[6]^[7] }}{{Ngc20}} 2 : NGC objects\|Taurus (constellation)
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