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: http://star.arm.ac.uk/~gar/research/rats.html
Дата изменения: Thu Jul 12 16:45:19 2007 Дата индексирования: Tue Oct 2 03:03:59 2012 Кодировка: Поисковые слова: spiral galaxy |
About Me Compact Binaries Cataclysmic Variables RATS Globular Clusters Jupiter PUBLICATIONS Preprints Armagh Observatory |
RApid Temporal Survey (RATS) This is the homepage of the RApid Time Survey (or RATS for short) home page. The main aim of this survey is to discover new stellar binary systems with orbital periods less than ~80 min. It is being led by Gavin Ramsay (Armagh Observatory) and Pasi Hakala (Tuorla Observatory) and collaborators include Ralf Napiwotzki (Herts), Harry Lehto (Tuorla), Gijs Nelemans (Nijmegen) and Steve Potter (SAAO).
Background:
Why is it important that we extend the parameter search down to periods shorter than 10 min? Recently several objects have been discovered, (RX J0806+15 and RX J1914+24), in which coherent intensity variations have been detected on timescales of ~10 min or less, with the shortest being 5.4 mins (see Cropper et al 2004 for a review). It is thought that these systems are interacting white dwarf-white dwarf pairs which have no accretion disc, and the observed period represents the binary orbital period. As such, they are expected to be amongst the first sources to be detected using LISA, the planned gravitational wave observatory (Nelemans, Yungleson & Portegies Zwart 2004). If these periods can be confirmed as their orbital period, then would be at the lower end of the orbital period distribution of interacting ultra-compact binary systems with white dwarf primaries (these objects are also called AM CVn systems). For a recent review of ultra-compacts see the recent article by Gijs Nelemans which appeared in Physics Today in July 2006. Strategy:Our strategy is to use wide field camera's on 2m class telescopes and take short exposures (~30 sec) in white light of the same field of sky for 2-3 hrs. We search for variable objects in each field and for those objects which are variable (in particular those showing modulation periods less than ~80 min) followup photometry and spectroscopy are required to determine their nature.
Pilot Survey:
Further Observations:
Links:
There was a week long workshop on ultra-compacts held in Nijmegen, The Netherlands, in July 2005. The presentations can be accessed from this site. Links to other projects whose aim is to detect new ultra-compacts include the Faint Variability Survey , and the Omega White Survey. |