Astronomical optical interferometry, II: Astrophysical results

Abstract

Optical interferometry is entering a new age with several ground- based long-baseline observatories now making observations of unprecedented spatial resolution. Based on a great leap forward in the quality and quantity of interferometric data, the astrophysical applications are not limited anymore to classical subjects, such as determination of fundamental properties of stars; namely, their effective temperatures, radii, luminosities and masses, but the present rapid development in this field allowed to move to a situation where optical interferometry is a general tool in studies of many astrophysical phenomena. Particularly, the advent of long-baseline interferometers making use of very large pupils has opened the way to faint objects science and first results on extragalactic objects have made it a reality. The first decade of XXI century is also remarkable for aperture synthesis in the visual and near-infrared wavelength regimes, which provided image reconstructions from stellar surfaces to Active Galactic Nuclei. Here I review the numerous astrophysical results obtained up to date, except for binary and multiple stars milliarcsecond astrometry, which should be a subject of an independent detailed review, taking into account its importance and expected results at microarcsecond precision level. To the results obtained with currently available interferometers, I associate the adopted instrumental settings in order to provide a guide for potential users concerning the appropriate instruments which can be used to obtain the desired astrophysical information

Differential interferometry of the rapid rotator Regulus

“…Stellar rotation was measured for the first time by interferometry, from the photocentre displacements by Lagarde (1994), on the slow rotator Aldebaran, which was observed in 1988 at OHP (Observatoire de Haute-Provence) through the 152cm telescope by the Speckle Differential Interferometry method. Results obtained by interferometry on the fast rotators were summarized by Jankov (2011) & van Belle (2012. The extreme stellar flattening induced by the rotation was measured by interferometry by Domiciano de Souza et al (2003) on Achernar (Req/R pol = 1.56 ± 0.05), using VLTI/VINCI (Very Large Telescope Interferometer/VLT INterferometer Commissioning Instrument) with a dense (u, v) coverage.…”

Binary star astrometry with milli and sub-milli arcsecond precision

“…Other PTI work on spectroscopic binaries allowed to determine astrometric orbits, which, when combined with the radial velocity measurements, determine all orbital parameters resulting in the mass determination for HD 195987 (M A = 0.844 ± 0.018M , M B = 0.665 ± 0.008M ) by Torres et al (2002), as well as for two double-lined spectroscopic binaries: σ Psc (M A = 2.65 ± 0.27M , M B = 2.36 ± 0.24M ) and HD 27483 (M A = 1.38 ± 0.13M , M B = 1.39 ± 0.13M ) by Konacki and Lane (2004) for which the latter had the smallest semi-major axis yet determined by the long base interferometry (1.2 mas).…”

“…While the optical interferometric techniques and instruments related to the present paper have been described in more detail in Jankov (2010) and astrophysical results in Jankov (2011), here we review the binary star results in the context of high resolution astrometry. The corresponding techniques are introduced in Section 1, and the results obtained from Speckle Interferometry in Section 2.…”

Interferometry and the study of protoplanetary disks

“…infrared and optical) interferometry, and instead point interested readers to several comprehensive reviews on this subject (e.g. Jankov 2010Jankov , 2011Malbet 2009;Monnier 2003;Monnier & Allen 2013) …”