Merope (star)

Merope
	Merope in the Pleiades cluster (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Taurus
Right ascension	03h 46m 19.5859s
Declination	+23° 56′ 54.092″
Apparent magnitude (V)	4.18
Characteristics
Spectral type	B6IV(e)
U−B color index	−0.41
B−V color index	−0.06
Variable type	β Cephei
Astrometry
Radial velocity (Rv)	6.2 km/s
Proper motion (μ)	RA: 13.075 mas/yr ; Dec.: −48.404 mas/yr
Parallax (π)	7.0670±0.2862 mas
Distance	460 ± 20 ly ; (142 ± 6 pc)
Absolute magnitude (MV)	−1.29
Details
Mass	4.25 M☉
Radius	4.79±0.17 R☉
Luminosity	927 L☉
Surface gravity (log g)	3.48 cgs
Temperature	14,550 K
Rotational velocity (v sin i)	240 km/s
Age	212 Myr
Other designations
	Merope, 23 Tau, V971 Tauri, HR 1156, BD+23°522, HD 23480, HIP 17608, SAO 76172, GC 4512, CCDM J03463+2357A
Database references
SIMBAD	data

Merope /ˈmɛrəpiː/,^[12] designated 23 Tauri (abbreviated 23 Tau), is a star in the constellation of Taurus and a member of the Pleiades star cluster. It is approximately 440 light-years (135 pc) away.

Distance

Despite being one of the closest star clusters to Earth, the distance to the Pleiades and its member stars is still in dispute. The parallax of Merope itself is not known precisely enough to give an accurate distance. Its Hipparcos parallax has a statistical margin of error of about 5% and gave a distance 116 parsecs. This, and an overall distance to the Pleiades calculated from Hipparcos parallaxes of 120 parsecs, are inconsistent with other parallax measurements such as from Gaia. Merope is too bright for Gaia to have a reliable parallax for it, but calculations of the overall distance to the Pleiades cluster using Hipparcos, Gaia, Hubble Space Telescope, and other methods repeatedly show that the Hipparcos parallaxes suffered from some kind of systemic error, and the distance to the Pleiades is most likely around 135 parsecs.^[13]^[14]^[15]^[16]^[17]

Description

A light curve for V971 Tauri (Merope), adapted from White *et al.* (2017)^[9]

Merope is a blue-white B-type subgiant with a mean apparent magnitude of +4.18. Richard Hinckley Allen described the star as lucid white and violet.^[18] It has a luminosity of 927 times that of the Sun and a surface temperature of 14,550 K. Merope's mass is roughly 4.25 M_☉ and has a radius 4.8 times as great as the Sun's.

In 1985, Bernard J. McNamara announced that the brightness of Merope varies as a function of time.^[19] Merope is classified as a Beta Cephei variable, a type of hot variable star which pulsates regularly due to opacity changes in its atmosphere. Its brightness varies by up to 0.01 magnitudes during each pulsation cycle.^[5] It is given the variable star designation of V971 Tauri. The period of variability is stable at 0.49 days, although the amplitude of the brightness changes on each cycle varies.^[9]

Some papers have reported a companion star to Merope, at a separation of 250 mas, as well as several other visual companions farther out. These possible companions have not been confirmed.^[20]

Surrounding Merope is the Merope Nebula (NGC 1435). It appears brightest around Merope and is listed in the Index Catalogue as number IC 349.

Nomenclature

23 Tauri is the star's Flamsteed designation. The name Merope originates with Greek mythology; she is one of the seven daughters of Atlas and Pleione known as the Pleiades. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)^[21] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016^[22] included a table of the first two batches of names approved by the WGSN; which included Merope for this star. It is now so entered in the IAU Catalog of Star Names.^[23]

References

^ ^a ^b ^c ^d ^e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ Ducati, J. R (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
^ Slettebak, A (1982). "Spectral types and rotational velocities of the brighter Be stars and A-F type shell stars". Astrophysical Journal Supplement Series. 50: 55. Bibcode:1982ApJS...50...55S. doi:10.1086/190820.
^ ^a ^b Crawford, D. L.; Barnes, J. V.; Golson, J. C. (1971). "Four-color, Hbeta, and UBV photometry for bright B-type stars in the northern hemisphere". The Astronomical Journal. 76: 1058. Bibcode:1971AJ.....76.1058C. doi:10.1086/111220.
^ ^a ^b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
^ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
^ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
^ Zorec, J.; Royer, F. (January 2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. ISSN 0004-6361. S2CID 55586789.
^ ^a ^b ^c White, T. R.; Pope, B. J. S.; Antoci, V.; Papics, P. I.; Aerts, C.; Gies, D. R.; Gordon, K.; Huber, D.; Schaefer, G. H.; Aigrain, S.; Albrecht, S.; Barclay, T.; Barentsen, G.; Beck, P. G.; Bedding, T. R.; Fredslund, M.; Andersen, M. Fredslund; Grundahl, F.; Howell, S. B.; Ireland, M. J.; Murphy, S. J.; Nielsen, M. B.; Aguirre, V. Silva; Tuthill, P. G. (November 2017). "Beyond the Kepler/K2 bright limit: variability in the seven brightest members of the Pleiades". Monthly Notices of the Royal Astronomical Society. 471 (3): 2882–2901. arXiv:1708.07462. Bibcode:2017MNRAS.471.2882W. doi:10.1093/mnras/stx1050.
^ ^a ^b ^c ^d Zorec, J.; et al. (November 2016). "Critical study of the distribution of rotational velocities of Be stars. I. Deconvolution methods, effects due to gravity darkening, macroturbulence, and binarity". Astronomy & Astrophysics. 595: 26. Bibcode:2016A&A...595A.132Z. doi:10.1051/0004-6361/201628760. hdl:11336/37946.
^ Gontcharov, G. A. (2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771–782. arXiv:1606.08814. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031. S2CID 118345778.
^ Davis, George A. (1944). "The pronunciations, derivations, and meanings of a selected list of star names". Popular Astronomy. 52: 8–30. Bibcode:1944PA.....52....8D.
^ Galli, P. A. B.; Moraux, E.; Bouy, H.; Bouvier, J.; Olivares, J.; Teixeira, R. (2017). "A revised moving cluster distance to the Pleiades open cluster". Astronomy and Astrophysics. 598: A48. arXiv:1610.05641. Bibcode:2017A&A...598A..48G. doi:10.1051/0004-6361/201629239. S2CID 119225372.
^ Melis, Carl; Reid, Mark J.; Mioduszewski, Amy J.; Stauffer, John R.; et al. (29 August 2014). "A VLBI resolution of the Pleiades distance controversy". Science. 345 (6200): 1029–1032. arXiv:1408.6544. Bibcode:2014Sci...345.1029M. doi:10.1126/science.1256101. PMID 25170147. S2CID 34750246.
^ Anthony G. A. Brown; GAIA Collaboration (2016). "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties". Astronomy and Astrophysics (forthcoming article). 595: A2. arXiv:1609.04172. Bibcode:2016A&A...595A...2G. doi:10.1051/0004-6361/201629512. S2CID 1828208.
^ Abramson, Guillermo (20 August 2018). "The Distance to the Pleiades According to Gaia DR2". Research Notes of the AAS. 2 (3): 150. Bibcode:2018RNAAS...2..150A. doi:10.3847/2515-5172/aada8b. hdl:11336/94435.
^ Soderblom D. R.; Nelan E.; Benedict G. F.; McArthur B.; et al. (2005). "Confirmation of Errors in Hipparcos Parallaxes from Hubble Space Telescope Fine Guidance Sensor Astrometry of the Pleiades". Astronomical Journal. 129 (3): 1616–1624. arXiv:astro-ph/0412093. Bibcode:2005AJ....129.1616S. doi:10.1086/427860. S2CID 15354711.
^ Merope, Star Names and their Meanings, Richard Hinckley Allen, Dover Publications, 1963, p. 407.
^ McNamara, B. J. (February 1985). "Maia variables and upper-main-sequence phenomena". Astrophysical Journal. 289: 213–219. Bibcode:1985ApJ...289..213M. doi:10.1086/162881. Retrieved 2 September 2025.
^ Hutter, D. J.; Tycner, C.; Zavala, R. T.; Benson, J. A.; Hummel, C. A.; Zirm, H. (2021). "Surveying the Bright Stars by Optical Interferometry. III. A Magnitude-limited Multiplicity Survey of Classical Be Stars". The Astrophysical Journal Supplement Series. 257 (2): 69. arXiv:2109.06839. Bibcode:2021ApJS..257...69H. doi:10.3847/1538-4365/ac23cb. S2CID 237503492.
^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
^ "IAU Catalog of Star Names". Retrieved 28 July 2016.

External links

Jim Kaler's Stars, University of Illinois:Merope (23 Tauri)
NGC 1435 - Merope Nebula LRGB image with 4 hours total exposure.

[edr3-1] Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.

[ducati-2] Ducati, J. R (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.

[slettebak-3] Slettebak, A (1982). "Spectral types and rotational velocities of the brighter Be stars and A-F type shell stars". Astrophysical Journal Supplement Series. 50: 55. Bibcode:1982ApJS...50...55S. doi:10.1086/190820.

[AJ1971-4] Crawford, D. L.; Barnes, J. V.; Golson, J. C. (1971). "Four-color, Hbeta, and UBV photometry for bright B-type stars in the northern hemisphere". The Astronomical Journal. 76: 1058. Bibcode:1971AJ.....76.1058C. doi:10.1086/111220.

[gcvs-5] Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.

[gcrv-6] Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.

[xhip-7] Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.

[zorec2012-8] Zorec, J.; Royer, F. (January 2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. ISSN 0004-6361. S2CID 55586789.

[White2017-9] White, T. R.; Pope, B. J. S.; Antoci, V.; Papics, P. I.; Aerts, C.; Gies, D. R.; Gordon, K.; Huber, D.; Schaefer, G. H.; Aigrain, S.; Albrecht, S.; Barclay, T.; Barentsen, G.; Beck, P. G.; Bedding, T. R.; Fredslund, M.; Andersen, M. Fredslund; Grundahl, F.; Howell, S. B.; Ireland, M. J.; Murphy, S. J.; Nielsen, M. B.; Aguirre, V. Silva; Tuthill, P. G. (November 2017). "Beyond the Kepler/K2 bright limit: variability in the seven brightest members of the Pleiades". Monthly Notices of the Royal Astronomical Society. 471 (3): 2882–2901. arXiv:1708.07462. Bibcode:2017MNRAS.471.2882W. doi:10.1093/mnras/stx1050.

[zorec2016-10] Zorec, J.; et al. (November 2016). "Critical study of the distribution of rotational velocities of Be stars. I. Deconvolution methods, effects due to gravity darkening, macroturbulence, and binarity". Astronomy & Astrophysics. 595: 26. Bibcode:2016A&A...595A.132Z. doi:10.1051/0004-6361/201628760. hdl:11336/37946.

[gontcharov2012-11] Gontcharov, G. A. (2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771–782. arXiv:1606.08814. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031. S2CID 118345778.

[Davis44-12] Davis, George A. (1944). "The pronunciations, derivations, and meanings of a selected list of star names". Popular Astronomy. 52: 8–30. Bibcode:1944PA.....52....8D.

[galli2017-13] Galli, P. A. B.; Moraux, E.; Bouy, H.; Bouvier, J.; Olivares, J.; Teixeira, R. (2017). "A revised moving cluster distance to the Pleiades open cluster". Astronomy and Astrophysics. 598: A48. arXiv:1610.05641. Bibcode:2017A&A...598A..48G. doi:10.1051/0004-6361/201629239. S2CID 119225372.

[vlbi2014-14] Melis, Carl; Reid, Mark J.; Mioduszewski, Amy J.; Stauffer, John R.; et al. (29 August 2014). "A VLBI resolution of the Pleiades distance controversy". Science. 345 (6200): 1029–1032. arXiv:1408.6544. Bibcode:2014Sci...345.1029M. doi:10.1126/science.1256101. PMID 25170147. S2CID 34750246.

[brown2016-15] Anthony G. A. Brown; GAIA Collaboration (2016). "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties". Astronomy and Astrophysics (forthcoming article). 595: A2. arXiv:1609.04172. Bibcode:2016A&A...595A...2G. doi:10.1051/0004-6361/201629512. S2CID 1828208.

[abramson2018-16] Abramson, Guillermo (20 August 2018). "The Distance to the Pleiades According to Gaia DR2". Research Notes of the AAS. 2 (3): 150. Bibcode:2018RNAAS...2..150A. doi:10.3847/2515-5172/aada8b. hdl:11336/94435.

[soderblom2005-17] Soderblom D. R.; Nelan E.; Benedict G. F.; McArthur B.; et al. (2005). "Confirmation of Errors in Hipparcos Parallaxes from Hubble Space Telescope Fine Guidance Sensor Astrometry of the Pleiades". Astronomical Journal. 129 (3): 1616–1624. arXiv:astro-ph/0412093. Bibcode:2005AJ....129.1616S. doi:10.1086/427860. S2CID 15354711.

[18] Merope, Star Names and their Meanings, Richard Hinckley Allen, Dover Publications, 1963, p. 407.

[ApJ1985-19] McNamara, B. J. (February 1985). "Maia variables and upper-main-sequence phenomena". Astrophysical Journal. 289: 213–219. Bibcode:1985ApJ...289..213M. doi:10.1086/162881. Retrieved 2 September 2025.

[Hutter-20] Hutter, D. J.; Tycner, C.; Zavala, R. T.; Benson, J. A.; Hummel, C. A.; Zirm, H. (2021). "Surveying the Bright Stars by Optical Interferometry. III. A Magnitude-limited Multiplicity Survey of Classical Be Stars". The Astrophysical Journal Supplement Series. 257 (2): 69. arXiv:2109.06839. Bibcode:2021ApJS..257...69H. doi:10.3847/1538-4365/ac23cb. S2CID 237503492.

[WGSN-21] "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.

[WGSN1-22] "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.

[IAU-CSN-23] "IAU Catalog of Star Names". Retrieved 28 July 2016.

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Observation data Epoch J2000 Equinox J2000
Merope in the Pleiades cluster (circled)
Constellation	Taurus
Right ascension	03^h 46^m 19.5859^s^[1]
Declination	+23° 56′ 54.092″^[1]
Apparent magnitude (V)	4.18^[2]
Characteristics
Spectral type	B6IV(e)^[3]
U−B color index	−0.41^[4]
B−V color index	−0.06^[4]
Variable type	β Cephei^[5]
Astrometry

Radial velocity (R_v)	6.2^[6] km/s
Proper motion (μ)	RA: 13.075^[1] mas/yr Dec.: −48.404^[1] mas/yr
Parallax (π)	7.0670±0.2862 mas^[1]
Distance	460 ± 20 ly (142 ± 6 pc)
Absolute magnitude (M_V)	−1.29^[7]

Details

Mass	4.25^[8] `M`_☉
Radius	4.79±0.17^[9] `R`_☉
Luminosity	927^[10] `L`_☉
Surface gravity (log g)	3.48^[10] cgs
Temperature	14,550^[10] K
Rotational velocity (v sin i)	240^[10] km/s
Age	212^[11] Myr

Other designations
Merope, 23 Tau, V971 Tauri, HR 1156, BD+23°522, HD 23480, HIP 17608, SAO 76172, GC 4512, CCDM J03463+2357A
Database references
SIMBAD	data

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