The diameters of $\alpha$ Centauri A and B - A comparison of the asteroseismic and VINCI/VLTI views

By Pierre Kervella, F. Thévenin, Damien Ségransan, G. Berthomieu, B. López, Pierre Morel, J. Provost. 2003

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We compare the first direct angular diameter measurements obtained on our closest stellar neighbour, Centauri, to recent model diameters constrained by asteroseismic observations. Using the VINCI instrument installed at ESO's VLT Interferometer (VLTI), the angular diameters of the two main components of the system, Cen A and B, were measured with a relative precision of 0.2% and 0.6% respectively. Particular care has been taken in the calibration of these measurements, considering that VINCI is estimating the fringe visibility using a broadband K filter. We obtain uniform disk angular diameters for Cen A and B ofUD(A) = 8:314 0:016 mas andUD(B) = 5:856 0:027 mas, and limb darkened angular diameters ofLD(A)= 8:511 0:020 mas andLD(B)= 6:001 0:034 mas. Combining these values with the parallax from Soderhjelm (1999), we derive linear diameters of D(A)= 1:224 0:003 D and D(B)= 0:863 0:005 D. These values are compatible with the masses published by Thevenin et al. (2002) for both stars.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/257f8ea5073fb88c0b09fbb5b9fd07e82453b693

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Citations in the corpus

The angular sizes of dwarf stars and subgiants Surface brightness relations calibrated by interferometry (2004, methodology): “Over the past two years, sixteen new angular diameter measurements of nearby Main Sequence and subgiant stars were obtained with the VLT Interferometer (Glindemann et al. 2000, 2003a,b) equipped with the fiber-based beam combiner VINCI (Kervella et al. 2000, 2003a).”
Circumstellar material in the Vega inner system revealed by CHARA/FLUOR (2006, methodology): “All diameters are derived from the visibility data points using a full model of the FLUOR instrument including the spectral bandwidth effects (Kervella et al. 2003).”
YREC: the Yale rotating stellar evolution code (2007, methodology): “…more asteroseismic data, is the detached binary system α Centauri: The masses of both components are known to high precision, the radius of the A component is measured with interferometric techniques (Kervella et al. 2003) and the luminosity is also well determined through parallax measurements.”
The Effective Temperature Scale of FGK Stars. I. Determination of Temperatures and Angular Diameters with the Infrared Flux Method (2005, unknown): “The original sources for the measured angular diameters include Lane et al. (2001), Kervella et al. (2003), Nordgren et al. (1999, 2001), and M03; as well as some other papers in preparation (see Kervella et al. 2004).”
The spinning-top Be star Achernar from VLTI-VINCI (2003, methodology): “The reduction procedure is detailed by Kervella et al. (2003) and has successfully been applied to dwarf stars observations with the VLTI (Ségransan et al. 2003).”
An investigation of the close environment of β Cephei with the VEGA/CHARA interferometer (2010, methodology): “This observational value should be compared to the one provided by classical asteroseismological study, using a method similar to the one performed on the solar-like star α Cen A and B (Thévenin, F. et al. 2002, Kervella et al. 2003).”
Gaia FGK benchmark stars: Effective temperatures and surface gravities (2015, methodology): “The diameters of the remaining stars were measured in the K band (2.2 µm) with either the VLT Interferometer (VLTI, VINCI instrument, Kervella et al. 2003a) or the CHARA Array using the Classic or FLUOR instrument, and in two cases, data from the Palomar Testbed Interferometer (PTI, California,…”