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Type II Cepheid

January 01, 1970

Type II Cepheids are variable stars which pulsate with periods typically between 1 and 50 days.[1][2] They are population II stars: old, typically metal-poor, low mass objects.[1]

H-R diagram illustrating the location of Type II Cepheids in the instability strip

Like all Cepheid variables, Type IIs exhibit a relationship between the star's luminosity and pulsation period, making them useful as standard candles for establishing distances where little other data is available[3][4]

Longer period Type II Cepheids, which are more luminous, have been detected beyond the Local Group in the galaxies NGC 5128 and NGC 4258.[5][6][7][8]

Classification edit

 
R Scuti Lightcurve (AAVSO)

Historically Type II Cepheids were called W Virginis variables, but are now divided into three subclasses based on the length of their period. Stars with periods between 1 and 4 days are of the BL Herculis subclass and 10–20 days belong to the W Virginis subclass. Stars with periods greater than 20 days, and usually alternating deep and shallow minima, belong to the RV Tauri subclass. RV Tauri variables are usually classified by a formal period from deep minimum to deep minimum, hence 40 days or more.[1][2]

The divisions between the types are not always clearcut or agreed. For example, the dividing line between BL Her and W Vir types is quoted at anything between 4 and 10 days, with no obvious division between the two. RV Tau variables may not have obvious alternating minima, while some W Vir stars do. Nevertheless, each type is thought to represent a distinct different evolutionary stage, with BL Her stars being helium core burning objects moving from the horizontal branch towards the asymptotic giant branch (AGB), W Vir stars undergoing hydrogen or helium shell burning on a blue loop, and RV Tau stars being post-AGB objects at or near the end of nuclear fusion.

RV Tau stars in particular show irregularities in their light curves, with slow variations in the brightness of both maxima and minima, variations in the period, intervals with little variation, and sometimes a temporary breakdown into chaotic behaviour. R Scuti has one of the most irregular light curves.

Properties edit

The physical properties of all the type II Cepheid variables are very poorly known. For example, it is expected that they have masses near or below that of the Sun, but there are few examples of reliable known masses.[9]

Period-luminosity relationship edit

Type II Cepheids are fainter than their classical Cepheid counterparts for a given period by about 1.6 magnitudes.[10] Cepheid variables are used to establish the distance to the Galactic Center, globular clusters, and galaxies.[5][11][12][13][14][15][16]

Examples edit

Type II Cepheids are not as well known as their type I counterparts, with only a couple of naked eye examples. In this list, the period quoted for RV Tauri variables is the interval between successive deep minima, hence twice the comparable period for the other sub-types.

This is a dynamic list and may never be able to satisfy particular standards for completeness. You can help by adding missing items with reliable sources.
Designation (name) Constellation Maximum Apparent magnitude (mv) Minimum Apparent magnitude (mv) Range of magnitude Period Spectral class Subtype Comment
RU Camelopardalis Camelopardalis 8.1 9.79 1.61 22 d C0,1-C3,2e(K0-R0) W Vir Carbon-rich[17]
Kappa Pavonis Pavo 3.91 4.78 0.87 9.09423 d F5-G5I-II W Vir brightest member
R Scuti Scutum 4.2 8.6 4.4 146.5 d G0Iae-K2p(M3)Ibe RV Tau brightest member
RV Tauri Taurus 9.5 13.5 4.0 78.5 d G2eIa-M2Ia RV Tau prototype
RT Trianguli Australis Triangulum Australe 9.43 10.18 0.35 1.9461124 d F8:(R)-G2I-II BL Her carbon-rich[18]
AL Virginis Virgo 9.10 9.92 0.82 10.3065 d F0-F8 W Vir  
W Virginis Virgo 9.46 10.75 0.87 17.2736 d F0Ib-G0Ib W Vir prototype
AF Crateris[19] Crater (constellation) 10.87 11.47 0.6 31.16 d F5 I RV Tau extremely metal poor, [Fe/H] = -2.7[19]

References edit

  1. ^ a b c Wallerstein, George (2002). "The Cepheids of Population II and Related Stars". The Publications of the Astronomical Society of the Pacific. 114 (797): 689–699. Bibcode:2002PASP..114..689W. doi:10.1086/341698.
  2. ^ a b Soszyński, I.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Wyrzykowski, Ł.; Szewczyk, O.; Ulaczyk, K.; Poleski, R. (2008). "The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. II.Type II Cepheids and Anomalous Cepheids in the Large Magellanic Cloud". Acta Astronomica. 58: 293. arXiv:0811.3636. Bibcode:2008AcA....58..293S.
  3. ^ Udalski, A.; Soszynski, I.; Szymanski, M.; Kubiak, M.; Pietrzynski, G.; Wozniak, P.; Zebrun, K. (1999). "The Optical Gravitational Lensing Experiment. Cepheids in the Magellanic Clouds. IV. Catalog of Cepheids from the Large Magellanic Cloud". Acta Astronomica. 49: 223–317. arXiv:astro-ph/9908317. Bibcode:1999AcA....49..223U.
  4. ^ Soszynski, I.; Poleski, R.; Udalski, A.; Szymanski, M. K.; Kubiak, M.; Pietrzynski, G.; Wyrzykowski, L.; Szewczyk, O.; Ulaczyk, K. (2008). "The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. I. Classical Cepheids in the Large Magellanic Cloud". Acta Astronomica. 58: 163. arXiv:0808.2210. Bibcode:2008AcA....58..163S.
  5. ^ a b Majaess, D.; Turner, D.; Lane, D. (2009). "Type II Cepheids as Extragalactic Distance Candles". Acta Astronomica. 59 (4): 403. arXiv:0909.0181. Bibcode:2009AcA....59..403M.
  6. ^ Macri, L. M.; Stanek, K. Z.; Bersier, D.; Greenhill, L. J.; Reid, M. J. (2006). "A New Cepheid Distance to the Maser-Host Galaxy NGC 4258 and Its Implications for the Hubble Constant". The Astrophysical Journal. 652 (2): 1133–1149. arXiv:astro-ph/0608211. Bibcode:2006ApJ...652.1133M. doi:10.1086/508530.
  7. ^ Ferrarese, Laura; Mould, Jeremy R.; Stetson, Peter B.; Tonry, John L.; Blakeslee, John P.; Ajhar, Edward A. (2007). "The Discovery of Cepheids and a Distance to NGC 5128". The Astrophysical Journal. 654 (1): 186–218. arXiv:astro-ph/0605707. Bibcode:2007ApJ...654..186F. doi:10.1086/506612.
  8. ^ Majaess, D. (2010). "The Cepheids of Centaurus A (NGC 5128) and Implications for H0". Acta Astronomica. 60 (2): 121. arXiv:1006.2458. Bibcode:2010AcA....60..121M.
  9. ^ Harris, Hugh C.; Welch, Douglas L. (September 1989). "The Binary Type II Cepheids IX CAS and TX Del". Astronomical Journal. 98: 981. Bibcode:1989AJ.....98..981H. doi:10.1086/115190.
  10. ^ "Cepheid Variables". Weekly Topic. Caglow. Retrieved 30 January 2012.
  11. ^ Kubiak, M.; Udalski, A. (2003). "The Optical Gravitational Lensing Experiment. Population II Cepheids in the Galactic Bulge". Acta Astronomica. 53: 117. arXiv:astro-ph/0306567. Bibcode:2003AcA....53..117K.
  12. ^ Matsunaga, Noriyuki; Fukushi, Hinako; Nakada, Yoshikazu; Tanabé, Toshihiko; Feast, Michael W.; Menzies, John W.; Ita, Yoshifusa; Nishiyama, Shogo; et al. (2006). "The period-luminosity relation for type II Cepheids in globular clusters". Monthly Notices of the Royal Astronomical Society. 370 (4): 1979–1990. arXiv:astro-ph/0606609. Bibcode:2006MNRAS.370.1979M. doi:10.1111/j.1365-2966.2006.10620.x.
  13. ^ Feast, Michael W.; Laney, Clifton D.; Kinman, Thomas D.; van Leeuwen, Floor; Whitelock, Patricia A. (2008). "The luminosities and distance scales of type II Cepheid and RR Lyrae variables". Monthly Notices of the Royal Astronomical Society. 386 (4): 2115. arXiv:0803.0466. Bibcode:2008MNRAS.386.2115F. doi:10.1111/j.1365-2966.2008.13181.x.
  14. ^ Majaess, Daniel J.; Turner, David G.; Lane, David J. (2009). "Characteristics of the Galaxy according to Cepheids". Monthly Notices of the Royal Astronomical Society. 398 (1): 263–270. arXiv:0903.4206. Bibcode:2009MNRAS.398..263M. doi:10.1111/j.1365-2966.2009.15096.x.
  15. ^ Majaess, D. J. (2010). "RR Lyrae and Type II Cepheid Variables Adhere to a Common Distance Relation". The Journal of the American Association of Variable Star Observers. 38 (1): 100–112. arXiv:0912.2928. Bibcode:2010JAVSO..38..100M.
  16. ^ Matsunaga, Noriyuki; Feast, Michael W.; Menzies, John W. (2009). "Period-luminosity relations for type II Cepheids and their application". Monthly Notices of the Royal Astronomical Society. 397 (2): 933. arXiv:0904.4701. Bibcode:2009MNRAS.397..933M. doi:10.1111/j.1365-2966.2009.14992.x.
  17. ^ Kipper, Tõnu; Klochkova, Valentina G. (2007). "Optical Spectroscopy of RU Cam, a Pulsating Carbon Star". Baltic Astronomy. 16: 383–96. arXiv:0706.2969. Bibcode:2007BaltA..16..383K.
  18. ^ Wallerstein, George; Matt, Sean; Gonzalez, Guillermo (2000), "The Carbon Cepheid RT Trianguli Australis: Additional Evidence of Triple-α and CNO Cycling", Monthly Notices of the Royal Astronomical Society, 311 (2): 414–22, Bibcode:2000MNRAS.311..414W, doi:10.1046/j.1365-8711.2000.03064.x
  19. ^ a b Van Winckel, H.; Hrivnak, B. J.; Gorlova, N.; Gielen, C.; Lu, W. (2012-06-01). "IRAS 11472-0800: an extremely depleted pulsating binary post-AGB star". Astronomy and Astrophysics. 542: A53. arXiv:1203.3416. doi:10.1051/0004-6361/201218835. ISSN 0004-6361.

External links edit

  • OGLE Atlas of Variable Star Light Curves - Type II Cepheids

January 01, 1970
type, cepheid, variable, stars, which, pulsate, with, periods, typically, between, days, they, population, stars, typically, metal, poor, mass, objects, diagram, illustrating, location, instability, strip, like, cepheid, variables, type, exhibit, relationship,. Type II Cepheids are variable stars which pulsate with periods typically between 1 and 50 days 1 2 They are population II stars old typically metal poor low mass objects 1 H R diagram illustrating the location of Type II Cepheids in the instability strip Like all Cepheid variables Type IIs exhibit a relationship between the star s luminosity and pulsation period making them useful as standard candles for establishing distances where little other data is available 3 4 Longer period Type II Cepheids which are more luminous have been detected beyond the Local Group in the galaxies NGC 5128 and NGC 4258 5 6 7 8 Contents 1 Classification 2 Properties 3 Period luminosity relationship 4 Examples 5 References 6 External linksClassification edit nbsp R Scuti Lightcurve AAVSO Historically Type II Cepheids were called W Virginis variables but are now divided into three subclasses based on the length of their period Stars with periods between 1 and 4 days are of the BL Herculis subclass and 10 20 days belong to the W Virginis subclass Stars with periods greater than 20 days and usually alternating deep and shallow minima belong to the RV Tauri subclass RV Tauri variables are usually classified by a formal period from deep minimum to deep minimum hence 40 days or more 1 2 The divisions between the types are not always clearcut or agreed For example the dividing line between BL Her and W Vir types is quoted at anything between 4 and 10 days with no obvious division between the two RV Tau variables may not have obvious alternating minima while some W Vir stars do Nevertheless each type is thought to represent a distinct different evolutionary stage with BL Her stars being helium core burning objects moving from the horizontal branch towards the asymptotic giant branch AGB W Vir stars undergoing hydrogen or helium shell burning on a blue loop and RV Tau stars being post AGB objects at or near the end of nuclear fusion RV Tau stars in particular show irregularities in their light curves with slow variations in the brightness of both maxima and minima variations in the period intervals with little variation and sometimes a temporary breakdown into chaotic behaviour R Scuti has one of the most irregular light curves Properties editThe physical properties of all the type II Cepheid variables are very poorly known For example it is expected that they have masses near or below that of the Sun but there are few examples of reliable known masses 9 Period luminosity relationship editType II Cepheids are fainter than their classical Cepheid counterparts for a given period by about 1 6 magnitudes 10 Cepheid variables are used to establish the distance to the Galactic Center globular clusters and galaxies 5 11 12 13 14 15 16 Examples editType II Cepheids are not as well known as their type I counterparts with only a couple of naked eye examples In this list the period quoted for RV Tauri variables is the interval between successive deep minima hence twice the comparable period for the other sub types This is a dynamic list and may never be able to satisfy particular standards for completeness You can help by adding missing items with reliable sources Designation name Constellation Maximum Apparent magnitude mv Minimum Apparent magnitude mv Range of magnitude Period Spectral class Subtype Comment RU Camelopardalis Camelopardalis 8 1 9 79 1 61 22 d C0 1 C3 2e K0 R0 W Vir Carbon rich 17 Kappa Pavonis Pavo 3 91 4 78 0 87 9 09423 d F5 G5I II W Vir brightest member R Scuti Scutum 4 2 8 6 4 4 146 5 d G0Iae K2p M3 Ibe RV Tau brightest member RV Tauri Taurus 9 5 13 5 4 0 78 5 d G2eIa M2Ia RV Tau prototype RT Trianguli Australis Triangulum Australe 9 43 10 18 0 35 1 9461124 d F8 R G2I II BL Her carbon rich 18 AL Virginis Virgo 9 10 9 92 0 82 10 3065 d F0 F8 W Vir W Virginis Virgo 9 46 10 75 0 87 17 2736 d F0Ib G0Ib W Vir prototype AF Crateris 19 Crater constellation 10 87 11 47 0 6 31 16 d F5 I RV Tau extremely metal poor Fe H 2 7 19 References edit a b c Wallerstein George 2002 The Cepheids of Population II and Related Stars The Publications of the Astronomical Society of the Pacific 114 797 689 699 Bibcode 2002PASP 114 689W doi 10 1086 341698 a b Soszynski I Udalski A Szymanski M K Kubiak M Pietrzynski G Wyrzykowski L Szewczyk O Ulaczyk K Poleski R 2008 The Optical Gravitational Lensing Experiment The OGLE III Catalog of Variable Stars II Type II Cepheids and Anomalous Cepheids in the Large Magellanic Cloud Acta Astronomica 58 293 arXiv 0811 3636 Bibcode 2008AcA 58 293S Udalski A Soszynski I Szymanski M Kubiak M Pietrzynski G Wozniak P Zebrun K 1999 The Optical Gravitational Lensing Experiment Cepheids in the Magellanic Clouds IV Catalog of Cepheids from the Large Magellanic Cloud Acta Astronomica 49 223 317 arXiv astro ph 9908317 Bibcode 1999AcA 49 223U Soszynski I Poleski R Udalski A Szymanski M K Kubiak M Pietrzynski G Wyrzykowski L Szewczyk O Ulaczyk K 2008 The Optical Gravitational Lensing Experiment The OGLE III Catalog of Variable Stars I Classical Cepheids in the Large Magellanic Cloud Acta Astronomica 58 163 arXiv 0808 2210 Bibcode 2008AcA 58 163S a b Majaess D Turner D Lane D 2009 Type II Cepheids as Extragalactic Distance Candles Acta Astronomica 59 4 403 arXiv 0909 0181 Bibcode 2009AcA 59 403M Macri L M Stanek K Z Bersier D Greenhill L J Reid M J 2006 A New Cepheid Distance to the Maser Host Galaxy NGC 4258 and Its Implications for the Hubble Constant The Astrophysical Journal 652 2 1133 1149 arXiv astro ph 0608211 Bibcode 2006ApJ 652 1133M doi 10 1086 508530 Ferrarese Laura Mould Jeremy R Stetson Peter B Tonry John L Blakeslee John P Ajhar Edward A 2007 The Discovery of Cepheids and a Distance to NGC 5128 The Astrophysical Journal 654 1 186 218 arXiv astro ph 0605707 Bibcode 2007ApJ 654 186F doi 10 1086 506612 Majaess D 2010 The Cepheids of Centaurus A NGC 5128 and Implications for H0 Acta Astronomica 60 2 121 arXiv 1006 2458 Bibcode 2010AcA 60 121M Harris Hugh C Welch Douglas L September 1989 The Binary Type II Cepheids IX CAS and TX Del Astronomical Journal 98 981 Bibcode 1989AJ 98 981H doi 10 1086 115190 Cepheid Variables Weekly Topic Caglow Retrieved 30 January 2012 Kubiak M Udalski A 2003 The Optical Gravitational Lensing Experiment Population II Cepheids in the Galactic Bulge Acta Astronomica 53 117 arXiv astro ph 0306567 Bibcode 2003AcA 53 117K Matsunaga Noriyuki Fukushi Hinako Nakada Yoshikazu Tanabe Toshihiko Feast Michael W Menzies John W Ita Yoshifusa Nishiyama Shogo et al 2006 The period luminosity relation for type II Cepheids in globular clusters Monthly Notices of the Royal Astronomical Society 370 4 1979 1990 arXiv astro ph 0606609 Bibcode 2006MNRAS 370 1979M doi 10 1111 j 1365 2966 2006 10620 x Feast Michael W Laney Clifton D Kinman Thomas D van Leeuwen Floor Whitelock Patricia A 2008 The luminosities and distance scales of type II Cepheid and RR Lyrae variables Monthly Notices of the Royal Astronomical Society 386 4 2115 arXiv 0803 0466 Bibcode 2008MNRAS 386 2115F doi 10 1111 j 1365 2966 2008 13181 x Majaess Daniel J Turner David G Lane David J 2009 Characteristics of the Galaxy according to Cepheids Monthly Notices of the Royal Astronomical Society 398 1 263 270 arXiv 0903 4206 Bibcode 2009MNRAS 398 263M doi 10 1111 j 1365 2966 2009 15096 x Majaess D J 2010 RR Lyrae and Type II Cepheid Variables Adhere to a Common Distance Relation The Journal of the American Association of Variable Star Observers 38 1 100 112 arXiv 0912 2928 Bibcode 2010JAVSO 38 100M Matsunaga Noriyuki Feast Michael W Menzies John W 2009 Period luminosity relations for type II Cepheids and their application Monthly Notices of the Royal Astronomical Society 397 2 933 arXiv 0904 4701 Bibcode 2009MNRAS 397 933M doi 10 1111 j 1365 2966 2009 14992 x Kipper Tonu Klochkova Valentina G 2007 Optical Spectroscopy of RU Cam a Pulsating Carbon Star Baltic Astronomy 16 383 96 arXiv 0706 2969 Bibcode 2007BaltA 16 383K Wallerstein George Matt Sean Gonzalez Guillermo 2000 The Carbon Cepheid RT Trianguli Australis Additional Evidence of Triple a and CNO Cycling Monthly Notices of the Royal Astronomical Society 311 2 414 22 Bibcode 2000MNRAS 311 414W doi 10 1046 j 1365 8711 2000 03064 x a b Van Winckel H Hrivnak B J Gorlova N Gielen C Lu W 2012 06 01 IRAS 11472 0800 an extremely depleted pulsating binary post AGB star Astronomy and Astrophysics 542 A53 arXiv 1203 3416 doi 10 1051 0004 6361 201218835 ISSN 0004 6361 External links editOGLE Atlas of Variable Star Light Curves Type II Cepheids Retrieved from https en wikipedia org w index php title Type II Cepheid amp oldid 1171340317, wikipedia, wiki, book, books, library,

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