NebulosityNGC 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. ItsHipparcos 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 fromGaia. 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]
Alight curve for V971 Tauri (Merope), adapted from Whiteet al. (2017)[9]
Merope is a blue-whiteB-typesubgiant with a meanapparent magnitude of +4.18.Richard Hinckley Allen described the star aslucid white and violet.[18] It has aluminosity of 927 times that of theSun and a surface temperature of14,550 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 aBeta Cephei variable, a type of hotvariable 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 thevariable star designation ofV971 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 of250 mas, as well as several other visual companions farther out. These possible companions have not been confirmed.[20]
Surrounding Merope is theMerope Nebula (NGC 1435). It appears brightest around Merope and is listed in theIndex Catalogue as numberIC 349.
^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.
^abSamus, 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.
^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.
