The young binary HD 102077: Orbit, spectral type, kinematics, and moving group membership

Abstract

The K-type binary star HD 102077 was proposed as a candidate member of the TW Hydrae Association (TWA) which is a young (5-15 Myr) moving group in close proximity (~50 pc) to the solar system. The aim of this work is to verify this hypothesis by different means. We first combine diffraction-limited observations from the ESO NTT 3.5m telescope in SDSS-i' and -z' passbands and ESO 3.6m telescope in H-band with literature data to obtain a new, amended orbit fit, estimate the spectral types of both components, and reanalyse the Hipparcos parallax and proper motion taking the orbital motion into account. Moreover, we use two high-resolution spectra of HD 102077 obtained with the fibre-fed optical echelle spectrograph FEROS at the MPG/ESO 2.2m telescope to determine the radial velocity and the lithium equivalent width of the system. The trajectory of HD 102077 is well constrained and we derive a total system mass of $2.6\pm 0.8$ M${}_{\odot }$ and a semi-major axis of $14.9\pm 1.6$AU. From the i'-z' colours we infer an integrated spectral type of K2V, and individual spectral types of K0 +/- 1 and K5 +/- 1. The radial velocity corrected for the orbital motion of the system is $17.6\pm 2$km/s. Even though the parallax determination from the Hipparcos data is not influenced by the orbital motion, the proper motion changes to ${\mu }_{\alpha }\ast \cos (\delta )=-137.84\pm 1.26$ mas/yr and ${\mu }_{\delta }=-33.53\pm 1.45$mas/yr. With the resultant space motion, the probability of HD 102077 being a member of TWA is less than 1%. Furthermore, the lithium equivalent width of $200\pm 4$mÅ is consistent with an age between 30 Myr and 120 Myr and thus older than the predicted age of TWA. In conclusion, HD 102077's age, galactic space motion, and position do not fit TWA or any other young moving group.

References in corpus (29)

• Validation of the new Hipparcos reduction
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs
• A box-fitting algorithm in the search for periodic transits
• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• Drizzle: A Method for the Linear Reconstruction of Undersampled Images
• The Geneva-Copenhagen Survey of the Solar neighbourhood II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk
• Speckle interferometry at the Blanco and SOAR telescopes in 2008 and 2009
• Bayesian analysis to identify new star candidates in nearby young stellar kinematic groups
• The Stellar Populations of Praesepe and Coma Berenices
• The Pisa pre-main sequence tracks and isochrones. A database covering a wide range of Z, Y, mass, and age values
• The Tucana/Horologium, Columba, AB Doradus, and Argus Associations: New Members and Dusty Debris Disks
• Effect of episodic accretion on the structure and the lithium depletion of low-mass stars and planet-hosting stars
• Identifying the young low-mass stars within 25 pc. II. Distances, kinematics and group membership
• Cool Young Stars in the Northern Hemisphere: Beta Pictoris and AB Doradus Moving Group Candidates
• Near-Infrared Variability in the 2MASS Calibration Fields: A Search for Planetary Transit Candidates
• Distance and Kinematics of the TW Hydrae Association from Parallaxes
• The GALEX Nearby Young-Star Survey
• Beta Pictoris and AB Doradus Moving Groups: Likely New Low-Mass Members
• Internal dynamics and membership of the NGC 3603 Young Cluster from microarcsecond astrometry
• Rotational velocities of nearby young stars
• Likely Members of the Beta Pictoris and AB Doradus Moving Groups in the North
• Orbits and Masses in the T Tauri System
• Unveiling new members in five nearby young moving groups
• IR Detection of Low-Mass Secondaries in Spectroscopic Binaries
• AstraLux - the Calar Alto 2.2-m telescope Lucky Imaging camera
• Additional TWA Members? : Spectroscopic verification of kinematically selected TWA candidates
• Reanalysis of the FEROS observations of HIP 11952
• Flare stars in the TW Hydrae association: The HIP 57269 system

Cited by in corpus (6)

• Imaging Extrasolar Giant Planets
• A Lucky Imaging search for stellar sources near 74 transit hosts
• A Lucky Imaging search for stellar companions to transiting planet host stars
• High Contrast Imaging with Spitzer : Constraining the Frequency of Giant Planets out to 1000 AU separations
• The LEECH Exoplanet Imaging Survey: Orbit and Component Masses of the Intermediate Age, Late-Type Binary NO UMa
• Multi-epoch, high spatial resolution observations of multiple T Tauri systems