OB1 stellar association, which is the largest association in the Carina Nebula, and it is bigger and more massive than . The star Eta Carinae is part of this cluster. Mystic Mountain Mystic Mountain is the term for a dust–gas pillar in the Carina Nebula, a photo of which was taken by Hubble Space Telescope on its 20th anniversary. The area was observed by Hubble's Wide Field Camera 3 on 1–2 February 2010. The pillar measures in height; nascent stars inside the pillar fire off gas jets that stream from towering “peaks”. WR 22 WR 22 is an eclipsing binary. The dynamical masses derived from orbital fitting vary from over to less than for the primary and about for the secondary. The spectroscopic mass of the primary has been calculated at or . WR 25 WR 25 is a binary system in the central portion of the Carina Nebula, a member of the cluster. The primary is a Wolf–Rayet star, possibly the most luminous star in the galaxy. The secondary is hard to detect but thought to be a luminous OB star. HD 93129 HD 93129 is a triple star system of O-class stars in Carina. All three stars of are among the most luminous in the galaxy; consists of two clearly resolved components, and , and itself is made up of two much closer stars. HD 93129 A has been resolved into two components. The spectrum is dominated by the brighter component, although the secondary is only 0.9 magnitudes fainter. is an O2 supergiant and Ab is an O3.5 main sequence star. Their separation has decreased from 55 milliarcseconds in 2004 to only 27 mas in 2013, but an accurate orbit is not available. HD 93129 B is an O3.5 main-sequence star 3 arcseconds away from the closer pair. It is about 1.5 magnitudes fainter than the combined , and is approximately the same brightness as . HD 93250 HD 93250 is one of the brightest stars in the region of the Carina Nebula. It is only 7.5 arcminutes from Eta Carinae, and is considered to be a member of the same loose open cluster , although it appears closer to the more compact . HD 93250 is known to be a binary star, however, individual spectra of the two components have never been observed but are thought to be very similar. The spectral type of has variously been