EDP Sciences
Free access
Volume 484, Number 3, June IV 2008
Page(s) 887 - 895
Section Astronomical instrumentation
DOI http://dx.doi.org/10.1051/0004-6361:20078669
Published online 28 April 2008

A&A 484, 887-895 (2008)
DOI: 10.1051/0004-6361:20078669

Direct determination of astronomical distances and proper motions by interferometric parallax

P. Jain1 and J. P. Ralston2

1  Physics Department, IIT, Kanpur 208016, India
    e-mail: pkjain@iitk.ac.in
2  Department of Physics and Astronomy, University of Kansas, Lawrence KS 66045, USA
    e-mail: ralston@ku.edu

Received 14 September 2007 / Accepted 13 April 2008

Aims. We discuss a new method for measuring the distances to astronomical objects and their transverse proper velocities.
Methods. The phenomenon of interferometric parallax identifies a component of 2- and 4-point amplitude and the intensity correlations that can be observed at frequencies ranging from radio to optical. The calculation hinges on terms depending on the source to receiver separation that are conventionally neglected in the Van Cittert-Zernicke theorem.
Results. Order of magnitude estimates find that the baselines of Earth-bound VLBI systems might be capable of measuring 10-100 kpc distance scales. In either the optical or radio regime, space-borne detectors with fine baseline control might resolve source distances of Gigaparsec order. We discuss the possibility that an independent distance ladder based directly on experimental measurement might be constructed on multiple scales.

Key words: techniques: interferometric -- astrometry -- instrumentation: interferometers

© ESO 2008