Main-Seqence Fitting Distance to the sigma Ori Cluster

Abstract

The sigma Ori cluster is an unbound aggregate of a few hundred young, low-mass stars centered on the multiple system sigma Ori. This cluster is of great interest because it is at an age when roughly half of the stars have lost their protoplanetary disks, and the cluster has a very large population of brown dwarfs. One of the largest sources of uncertainty in the properties of the cluster is that the distance is not well known. The directly measured Hipparcos distance to sigma Ori AB is 350 (+120,-90) pc. On the other hand, the distance to the Orion OB1b subgroup (of which sigma Ori is thought to be a member), 473+/-40 pc, is far better determined, but it is an indirect estimate of the cluster's distance. Also, Orion OB1b may have a depth of 40 pc along our line of sight. We use main sequence fitting to 9 main sequence cluster members to estimate a best fit distance of 420+/-30 pc, assuming a metallicity of -0.16+/-0.11 or 444 pc assuming solar metallicity. A distance as close as 350 pc is inconsistent with the observed brightnesses of the cluster members. At the best fit distance, the age of the cluster is 2-3 Myrs.

Accepted by AJ

References in corpus (3)

• The distance to the Orion Nebula
• The Distances to Open Clusters from Main-Sequence Fitting. III. Improved Accuracy with Empirically Calibrated Isochrones
• The brightest stars of the sigma Orionis cluster

Cited by in corpus (15)

• The Gould's Belt Distances Survey (GOBELINS) II. Distances and structure towards the Orion Molecular Clouds
• Orbits, Distance, and Stellar Masses of the Massive Triple Star Sigma Orionis
• Orbital and physical properties of the $\sigma$ Ori Aa,Ab,B triple system
• Trigonometric parallaxes of young field L dwarfs
• A spectroscopic census in young stellar regions: the Sigma Orionis cluster
• A deep look into the cores of young clusters I. sigma-Orionis
• The Gaia-ESO Survey: the first abundance determination of the pre-main-sequence cluster Gamma Velorum
• A Pulsation Search Among Young Brown Dwarfs and Very Low Mass Stars
• Mapping young stellar populations towards Orion with Gaia DR1
• Low-resolution spectroscopy and spectral energy distributions of selected sources towards sigma Orionis
• Testing external photoevaporation in the $\sigma$-Orionis cluster with spectroscopy and disk mass measurements
• An Infrared Census of Star Formation in the Horsehead Nebula
• New deep XMM-Newton observations to the west of the sigma Orionis cluster
• Characterization of the known T type dwarfs towards the Sigma Orionis cluster
• A deep staring campaign in the Sigma Orionis cluster. Variability in substellar members