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5 results on '"Burleigh, M.R."'

2. A survey for post-common-envelope binary stars using GALEX and SDSS photometry

Author

Maxted, P.F.L., Gänsicke, B.T., Burleigh, M.R., Southworth, J., Marsh, T.R., Napiwotzki, R., Nelemans, G.A., and Wood, P.L.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astronomy, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

We report the first results of our programme to obtain multi-epoch radial velocity measurements of stars with a strong far-UV excess to identify post common-envelope binaries (PCEBs). The targets have been identified using optical photometry from SDSS DR4, ultraviolet photometry from GALEX GR2 and proper motion information from SDSS DR5. We have obtained spectra at two or more epochs for 36 targets. Three of our targets show large radial velocity shifts (>50km/s) on a timescale of hours or days and are almost certainly PCEBs. For one of these targets (SDSS J104234.77+644205.4) we have obtained further spectroscopy to confirm that this is a PCEB with an orbital period of 4.74h and semi-amplitude K =165 km/s. Two targets are rapidly rotating K-dwarfs which appear to show small radial velocity shifts and have strong Ca II H+K emission lines. These may be wind-induced rapidly rotating (WIRRing) stars. These results show that we can use GALEX and SDSS photometry to identify PCEBs that cannot be identified using SDSS photometry alone, and to identify new WIRRing stars. A more comprehensive survey of stars identified using the methods developed in this paper will lead to a much improved understanding of common envelope evolution., 11 pages, 7 figures, accepted for publication in MNRAS

Published
2009

3. Rotational period of WD1953-011 - a magnetic white dwarf with a star spot

Author

Brinkworth, C.S., Marsh, T.R., Morales-Rueda, L., Maxted, P.F.L., Burleigh, M.R., and Good, S.A.

Subjects
Astronomy, Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics
Abstract

WD1953-011 is an isolated, cool (7920 +/- 200K, Bergeron, Legget & Ruiz, 2001) magnetic white dwarf (MWD) with a low average field strength (~70kG, Maxted et al. 2000) and a higher than average mass (~0.74 M_sun, Bergeron et al. 2001). Spectroscopic observations taken by Maxted et al. (2000) showed variations of equivalent width in the Balmer lines, unusual in a low field white dwarf. Here we present V band photometry of WD1953-011 taken at 7 epochs over a total of 22 months. All of the datasets show a sinusoidal variation of approximately 2% peak-to-peak amplitude. We propose that these variations are due to a star spot on the MWD, analogous to a sunspot, which is affecting the temperature at the surface, and therefore its photometric magnitude. The variations have a best-fit period over the entire 22 months of 1.4418 days, which we interpret as the rotational period of the WD., (1) University of Southampton, (2) University of Warwick, (3) University of Nijmegen, (4) Keele University, (5) University of Leicester. 6 pages, 5 figs, accepted MNRAS

Published
2004

4. A comparison of DA white dwarf temperatures and gravities from FUSE Lyman line and ground-based Balmer line observations.

Author

Barstow, M.A., Good, S.A., Burleigh, M.R., Hubeny, I., Holberg, J.B., and Levan, A.J.

Subjects
WHITE dwarf stars, STARS, ASTRONOMY
Abstract

ABSTRACT The observation of the strengths and profiles of the hydrogen Balmer absorption series is an established technique for determining the effective temperature and surface gravity of hot H-rich white dwarf stars. In principle, the Lyman series lines should be equally useful but, lying in the far-ultraviolet (FUV), are only accessible from space. Nevertheless, there are situations (for example, where the optical white dwarf spectrum is highly contaminated by the presence of a companion) in which use of the Lyman series may be essential. Therefore, it is important to establish whether or not the Lyman lines provide an equally valid means of measurement. We have already made a first attempt to study this problem, comparing Lyman line measurements from a variety of FUV instruments with ground-based Balmer line studies. Within the measurement uncertainties, we found the results from each line series to be broadly in agreement. However, we noted a number of potential systematic effects that could bias either measurement. With the availability of the Far Ultraviolet Spectroscopic Explorer (FUSE ) data archive and observations from our own Guest Observer programmes, we now have an opportunity to examine the use of the Lyman series in more detail from observations of 16 DA white dwarfs. Here we have data produced by a single instrument and processed with a uniform data reduction pipeline, eliminating some of the possible systematic differences between observations of the same or different stars. We have also examined the scatter in values derived from multiple observations of the same star, which is significant. The new results partially reproduce the earlier study, showing that Balmer and Lyman line determined temperatures are in good agreement up to ∼50 000 K. However, above this value there is an increasing systematic difference between the Lyman and Balmer line results, the former yielding the higher temperature. At the moment, there is no clear explanation of this effect but we think that it is most likely associated with deficiencies in the detailed physics incorporated into the stellar model atmosphere calculations. Even so, the data do demonstrate that, for temperatures below 50 000 K, the Lyman lines give reliable results. Furthermore, for the hotter stars, a useful empirical calibration of the relationship between the Lyman and Balmer measurements has been obtained, which can be applied to other FUSE observations. [ABSTRACT FROM AUTHOR]

Published
2003
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5. Follow-up Observations of SPY White Dwarf + M-Dwarf Binaries

Author

Maxted, P.F.L., Napiwotzki, R., Marsh, T.R., Burleigh, M.R., Dobbie, P.D., Hogan, E., Nelemans, G.A., and Napiwotzki, R.

Subjects
musculoskeletal diseases, endocrine system, congenital, hereditary, and neonatal diseases and abnormalities, endocrine system diseases, Astronomy, Astrophysics::Instrumentation and Methods for Astrophysics, food and beverages, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, ASP Conference Series, Astrophysics::Galaxy Astrophysics
Abstract

Contains fulltext : 34787.pdf (Publisher’s version ) (Closed access) We present the results of follow-up observations of white-dwarf + M-dwarf binaries identified using spectra obtained as part of the SPY survey. Spectra of the Halpha region were obtained with the SPIRAL spectrograph on the AAT telescope. Of the eleven stars observed, seven are binaries with periods in the range 2.8 hours to 7.7 days. We also show that one of our targets, WD 0137-349, has a brown dwarf companion. 15th European Workshop on White Dwarfs

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