The Ages of A-Stars I: Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group

Abstract

We have observed and spatially resolved a set of seven A-type stars in the nearby Ursa Major moving group with the Classic, CLIMB, and PAVO beam combiners on the CHARA Array. At least four of these stars have large rotational velocities ($v\sin i$ $\gtrsim$ 170 $\mathrm{km}{\mathrm{s}}^{-1}$) and are expected to be oblate. These interferometric measurements, the stars' observed photometric energy distributions, and $v\sin i$ values are used to computationally construct model oblate stars from which stellar properties (inclination, rotational velocity, and the radius and effective temperature as a function of latitude, etc.) are determined. The results are compared with MESA stellar evolution models (Paxton et al. 2011, 2013) to determine masses and ages. The value of this new technique is that it enables the estimation of the fundamental properties of rapidly rotating stars without the need to fully image the star. It can thus be applied to stars with sizes comparable to the interferometric resolution limit as opposed to those that are several times larger than the limit. Under the assumption of coevality, the spread in ages can be used as a test of both the prescription presented here and the MESA evolutionary code for rapidly rotating stars. With our validated technique, we combine these age estimates and determine the age of the moving group to be 414 $\pm$ 23 Myr, which is consistent with, but much more precise than previous estimates.

arXiv commentAccepted by ApJ

References in corpus (37)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Validation of the new Hipparcos reduction
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Accurate masses and radii of normal stars: modern results and applications
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• Theoretical isochrones in several photometric systems I. Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Washington, and ESO Imaging Survey filter sets
• Images of a fourth planet orbiting HR 8799
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• Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I
• The VAST Survey - III. The multiplicity of A-type stars within 75 pc
• Imaging the Surface of Altair
• Interferometric Observations of Rapidly Rotating Stars
• Gravity darkening in rotating stars
• Rotational velocities of A-type stars IV. Evolution of rotational velocities
• Rotational velocities of A-type stars. III. Velocity distributions
• Parallactic Motion for Companion Discovery: An M-Dwarf Orbiting Alcor
• Discovery of a Faint Companion to Alcor Using MMT/AO 5 $\mu$m Imaging
• Stellar Diameters and Temperatures I. Main Sequence A, F, & G Stars
• First Results from the CHARA Array. I. An Interferometric and Spectroscopic Study of the Fast Rotator alpha Leonis (Regulus)
• First Results from the CHARA Array VII: Long-Baseline Interferometric Measurements of Vega Consistent with a Pole-On, Rapidly Rotating Star
• The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets
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• Populations of rotating stars. - I. Models from 1.7 to 15 Msun at Z = 0.014, 0.006, and 0.002 with Ω/Ωcrit between 0 and 1
• Resolving Vega and the inclination controversy with CHARA/MIRC
• Age determination of the HR8799 planetary system using asteroseismology
• High-Resolution Spectroscopy of Ursa Major Moving Group Stars
• Establishing Visible Interferometer System Responses: Resolved and Unresolved Calibrators
• Building the 'JMMC Stellar Diameters Catalog' using SearchCal
• Extrasolar planets and brown dwarfs around A-F type stars. IV. A candidate brown dwarf around the A9V pulsating star HD180777
• A substellar component orbiting the F-star 30 Ari B
• Spectroscopic properties of cool Ursa Major group members
• Normal A0--A1 stars with low rotational velocities. I. Abundance determination and classification
• Direct Detection of the Companion of Chi 1 Orionis
• Astrometric and Photometric Measurements of Binary Stars with Adaptive Optics: Observations from 2002

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