Merope (star)

Merope

Template:Location mark Merope in the Pleiades cluster (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Taurus
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	4.18
Characteristics
Spectral type	B6IV(e)
U−B Template:Engvar	−0.41
B−V Template:Engvar	−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	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	−1.29
Details
Mass	4.25 Template:Solar mass
Radius	Template:Val Template:Solar radius
Luminosity	927 Template:Solar luminosity
Surface gravity (log g)	3.48 cgs
Temperature	14,550 K
Rotational velocity (v sin i)	240 km/s
Age	212 Myr
Metallicity [Fe/H]	{{{metal_fe2}}} dex
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 Template:IPAc-en, 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 Template:Convert away.

Distance

File:Pleiades Spitzer big.jpg

Nebulosity NGC 1435 around Merope (Spitzer false colour infrared image)

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.

Description

File:V971TauLightCurve.png

A light curve for V971 Tauri (Merope), adapted from White et al. (2017)

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. It has a luminosity of 927 times that of the Sun and a surface temperature of Template:Val. Merope's mass is roughly Template:Solar mass and has a radius 4.8 times as great as the Sun's.

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. 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.

Some papers have reported a companion star to Merope, at a separation of Template:Val, as well as several other visual companions farther out. These possible companions have not been confirmed.

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) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 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.

External links

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