The 'DODO' survey -I. Limits on ultra-cool substellar and planetary-mass companions to van Maanen's star (vMa2)
Monthly Notices of the Royal Astronomical Society: Letters 386:1 (2008)
Abstract:
We report limits in the planetary-mass regime for companions around the nearest single white dwarf to the Sun, van Maanen's star (vMa 2), from deep J-band imaging with Gemini North and Spitzer Infrared Array Camera (IRAC) mid-IR photometry. We find no resolved common proper motion companions to vMa 2 at separations from 3 to 45 arcsec, at a limiting magnitude of J ≈ 23. Assuming a total age for the system of 4.1 ± 1 Gyr, and utilizing the latest evolutionary models for substellar objects, this limit is equivalent to companion masses >7 ± 1 MJup(Teff ≈ 300 K). Taking into account the likely orbital evolution of very low mass companions in the post-main-sequence phase, these J-band observations effectively survey orbits around the white dwarf progenitor from 3 to 50 au. There is no flux excess detected in any of the complimentary Spitzer IRAC mid-IR filters. We fit a white dwarf model atmosphere to the optical BVRI, JHK and IRAC photometry. The best solution gives Teff = 6030 ± 240 K, log g = 8.10 ± 0.04 and, hence, M = 0.633 ± 0.022 M⊙. We then place a 3σ upper limit of 10 ± 2MJup on the mass of any unresolved companion in the 4.5 μm band. © 2008 The Authors. Journal compilation © 2008 RAS.A search for J-band variability from late-L and T brown dwarfs
Monthly Notices of the Royal Astronomical Society 386:4 (2008) 2009-2014
Abstract:
We present J-band photometric observations of eight late-L and T type brown dwarfs designed to search for variability. We detect small amplitude periodic variability from three of the objects on time-scales of several hours, probably indicating the rotation period of the objects. The other targets do not show any variability down to the level of 0.5-5 per cent © 2008 RAS.Exploring High Contrast Limitations for Image Slicer Based Integral Field Spectrographs
ADAPTIVE OPTICS SYSTEMS, PTS 1-3 7015 (2008) ARTN 70156R
SWIFT de-magnifying image slicer: Diffraction limited image slicing at optical wavelengths
ADVANCED OPTICAL AND MECHANICAL TECHNOLOGIES IN TELESCOPES AND INSTRUMENTATION, PTS 1-3 7018 (2008) ARTN 70182O
The GlobalJetWatch spectrographs: a fibre-fed spectrograph for small telescopes - art. no. 70145A
GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY II, PTS 1-4 7014 (2008) A145-A145