Predicting Gaia's Parallax Distance to the Cygnus OB2 Association with Eclipsing Binaries

Abstract

The Cygnus OB2 Association is one of the nearest and largest collections of massive stars in the Galaxy. Situated at the heart of the "Cygnus X" complex of star-forming regions and molecular clouds, its distance has proven elusive owing to the ambiguous nature of kinematic distances along this $\ell \simeq 80$ degree sightline and the heavy, patchy extinction. In an effort to refine the three-dimensional geometry of key Cygnus~X constituents, we have measured distances to four eclipsing double-lined OB-type spectroscopic binaries that are probable members of Cyg~OB2. We find distances of $1.33\pm 0.17$, $1.32\pm 0.07$, $1.44\pm 0.18$, and $1.32\pm 0.13$ kpc toward MT91~372, MT91~696, CPR2002~A36, and Schulte~3 respectively. We adopt a weighted average distance of 1.33$\pm$0.06~kpc. This agrees well with spectrophotometric estimates for the Association as a whole and with parallax measurements of protostellar masers in the surrounding interstellar clouds, thereby linking the ongoing star formation in these clouds with Cyg~OB2. We also identify Schulte 3C (O9.5V), a 4" visual companion to the 4.75 day binary Schulte~3(A+B), as a previously unrecognized Association member.

20 pages, 13 figures, accepted to the Astrophysical Journal

References in corpus (12)

• An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology
• Mass loss from hot massive stars
• The UKIDSS Galactic Plane Survey
• The earliest phases of high-mass star formation: a 3 square degree millimeter continuum mapping of Cygnus X
• Toward Complete Statistics of Massive Binary Stars: Penultimate Results from the Cygnus OB2 Radial Velocity Survey
• The Massive Star Population of Cygnus OB2
• The Struve-Sahade effect in the optical spectra of O-type binaries I. Main-sequence systems
• A multiwavelength investigation of the massive eclipsing binary Cyg OB2 #5
• The Distance and Size of the Red Hypergiant NML Cyg from VLBA and VLA Astrometry
• New Massive Binaries in the Cygnus OB2 Association
• The Interacting Early-Type Binary V382 Cyg
• Separated before birth: pulsars B2020+28 and B2021+51 as the remnants of runaway stars

Cited by in corpus (26)

• The Galactic O-Star Spectroscopic Survey (GOSSS). III. 142 additional O-type systems
• On the Origin of Black Hole Spin in High-mass X-Ray Binaries
• Cygnus OB2 DANCe: A high precision proper motion study of the Cygnus OB2 association
• Empirical Bolometric Correction Coefficients for Nearby Main-Sequence Stars in Gaia Era
• Multiwavelength monitoring and X-ray brightening of Be X-ray binary PSR J2032+4127/MT91 213 on its approach to periastron
• Binary Pulsar Distances and Velocities from Gaia Data Release 2
• The Villafranca catalog of Galactic OB groups: I. Systems with O2-O3.5 stars
• Spectroscopic characterization of the known O-star population in Cygnus OB2. Evidence of multiple star-forming bursts
• Infrared Photometric Properties of 709 Candidate Stellar Bowshock Nebulae
• External photoevaporation of protoplanetary discs in Cygnus OB2: linking discs to star formation dynamical history
• Remote Operations and Nightly Automation of The Red Buttes Observatory
• Demonstration of a novel method for measuring mass-loss rates for massive stars
• e-MERLIN 21cm constraints on the mass-loss rates of OB stars in Cyg OB2
• X-ray mapping of the stellar wind in the binary PSR J2032+4127/MT91 213
• Gamma-Ray Puzzles in Cygnus X: Implications for High-Energy Neutrinos
• Near-Infrared Time-Series Photometry in the Field of Cygnus OB2 Association I - Rotational Scenario For Candidate Members
• A Survey for High-Mass Eclipsing Binaries
• Identifying Galactic Sources of High-Energy Neutrinos
• A HaloSat Analysis of the Cygnus Superbubble
• Near-infrared time-series photometry in the field of Cygnus OB2 association II. Mapping the variability of candidate members
• Gamma-rays from the binary system containing PSR J2032+4127 during its periastron passage
• The velocity structure of Cygnus OB2
• A High Angular Resolution Survey of Massive Stars in Cygnus OB2: $JHK$ Adaptive Optics Results from the Gemini Near-InfraRed Imager
• COBRaS: The e-MERLIN 21 cm Legacy survey of Cygnus OB2
• Properties of dwarf stars in Cygnus OB2
• Deciphering the gamma-ray emission in the Cygnus region