• DOI:10.1002/asna.200710827
• Corpus ID: 14027548

On the distance to the Ophiuchus star-forming region

@article{Mamajek2007OnTD,
  title={On the distance to the Ophiuchus star-forming region},
  author={Eric E. Mamajek},
  journal={Astronomische Nachrichten},
  year={2007},
  volume={329},
  pages={10-14}
}

• E. Mamajek
• Published 4 September 2007
• Chemistry
• Astronomische Nachrichten

The Ophiuchus molecular cloud complex has produced in Lynds 1688 the richest known embedded cluster within ∼300 pc of the Sun. Unfortunately, distance estimates to the Oph complex vary by nearly ∼40% (∼120–165 pc). Here I calculate a new independent distance estimate of 135±8 pc to this benchmark star-forming region based on Hipparcos trigonometric parallaxes to stars illuminating reflection nebulosity in close proximity to Lynds 1688. Combining this value with recent distance estimates from reddening studies suggests a consensus distance of 139±6 pc (4% error), situating it within ∼11 pc of the centroid of the ∼5 Myr old Upper Sco OB subgroup of Sco OB2 (145 pc). The velocity vectors for Oph and Upper Sco are statistically indistinguishable within ∼1 km s–1 in each vector component. Both Oph and Upper Sco have negligible motion (<1 km s–1) in the Galactic vertical direction with respect to the Local Standard of Rest, which is inconsistent with the young stellar groups having formed via the high velocity cloud impact scenario. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)