[show abstract][hide abstract] ABSTRACT: Building on the experience of the high-resolution community with the suite of
VLT high-resolution spectrographs, which has been tremendously successful, we
outline here the (science) case for a high-fidelity, high-resolution
spectrograph with wide wavelength coverage at the E-ELT. Flagship science
drivers include: the study of exo-planetary atmospheres with the prospect of
the detection of signatures of life on rocky planets; the chemical composition
of planetary debris on the surface of white dwarfs; the spectroscopic study of
protoplanetary and proto-stellar disks; the extension of Galactic archaeology
to the Local Group and beyond; spectroscopic studies of the evolution of
galaxies with samples that, unlike now, are no longer restricted to strongly
star forming and/or very massive galaxies; the unraveling of the complex roles
of stellar and AGN feedback; the study of the chemical signatures imprinted by
population III stars on the IGM during the epoch of reionization; the exciting
possibility of paradigm-changing contributions to fundamental physics. The
requirements of these science cases can be met by a stable instrument with a
spectral resolution of R~100,000 and broad, simultaneous spectral coverage
extending from 370nm to 2500nm. Most science cases do not require spatially
resolved information, and can be pursued in seeing-limited mode, although some
of them would benefit by the E-ELT diffraction limited resolution. Some
multiplexing would also be beneficial for some of the science cases. (Abridged)
[show abstract][hide abstract] ABSTRACT: We outline the purpose, strategy and first results of a deep, high cadence,
photometric survey of the Kepler field using the Isaac Newton Telescope on La
Palma and the MDM 1.3m Telescope on Kitt Peak. Our goal was to identify sources
located in the Kepler field of view which are variable on a timescale of a few
mins to 1 hour. The astrophysically most interesting sources would then have
been candidates for observation using Kepler using 1 min sampling. Our survey
covered ~42% of the Kepler field of view and we have obtained light curves for
7.1x10^5 objects in the range 13<g<20. We have discovered more than 100
variable sources which have passed our two stage identification process. As a
service to the wider community, we make our data products and cleaned CCD
images available to download. We obtained Kepler data of 18 sources which we
found to be variable using our survey and we give an overview of the currently
available data here. These sources include a pulsating DA white dwarf, eleven
delta Sct stars which have dominant pulsation periods in the range 24 min to
2.35 hrs, three contact binaries, and a cataclysmic variable (V363 Lyr). One of
the delta Sct stars is in a contact binary.
[show abstract][hide abstract] ABSTRACT: We present an ultraviolet spectrum and light curve of the short orbital
period cataclysmic variable EZ Lyn obtained with the Cosmic Origins
Spectrograph on the Hubble Space Telescope 14 months after its dwarf nova
outburst, along with ground-based optical photometry. The UV spectrum can be
fit with a 13,100K, log g=8 white dwarf using 0.5 solar composition, while fits
to the individual lines are consistent with solar abundance for Si and Al, but
only 0.3 solar for C. The Discrete Fourier Transforms of the UV and optical
light curves at 14 months following outburst show a prominent period at 256
sec. This is the same period reported by Pavlenko in optical data obtained 7
months and one year after outburst, indicating its long term stability over
several months, but this period is not evident in the pre-outburst data and is
much shorter than the 12.6 min period that was seen in observations obtained
during an interval from 8 months to 2.5 years after the 2006 outburst. In some
respects, the long and short periods are similar to the behavior seen in GW Lib
after its outburst but the detailed explanation for the appearance and
disappearance of these periods and their relation to non-radial pulsation modes
remain to be explored with theoretical models.
[show abstract][hide abstract] ABSTRACT: To determine the spectral type, the rotational velocity and the radial
velocity amplitude of the primary, we obtained 46 high-resolution
(R~85000) echelle spectra using the HERMES spectrograph at the 1.2-m
Mercator telescope (La Palma, Canary Islands). These were reduced using
the standard instrument-specific data reduction pipeline. Additionally,
we obtained 29 spectra with the ISIS spectrograph mounted on the 4.2-m
William Herschel Telescope (La Palma, Canary Islands).
The Kepler data from Q0 (quarter 0), Q1, Q2 and Q3 were retrieved from
the public archive (http://archive.stsci.edu/kepler/). The data span
229-d, resulting in a data set of 212-d of observations excluding the
(6 data files).
[show abstract][hide abstract] ABSTRACT: We present the results of the first spectroscopic follow-up of 132 optically
blue UV-excess sources selected from the UV-excess survey of the Northern
Galactic Plane (UVEX). The UV-excess spectra are classified into different
populations and grids of model spectra are fit to determine spectral types,
temperatures, surface gravities and reddening. From this initial spectroscopic
follow-up 95% of the UV-excess candidates turn out to be genuine UV-excess
sources such as white dwarfs, white dwarf binaries, subdwarfs type O and B,
emission line stars and QSOs. The remaining sources are classified as slightly
reddened main-sequence stars with spectral types later than A0V. The fraction
of DA white dwarfs is 47% with reddening smaller than E(B-V)<0.7 mag. Relations
between the different populations and their UVEX photometry, Galac- tic
latitude and reddening are shown. A larger fraction of UVEX white dwarfs is
found at magnitudes fainter than g>17 and Galactic latitude smaller than |b|<4
compared to main-sequence stars, blue horizontal branch stars and subdwarfs.
Monthly Notices of the Royal Astronomical Society 06/2012; 426(2). · 5.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: These tables show the objects from the spectroscopic and
photometric-only samples in "spec.dat" and "phot.dat" respectively. The
table ire.dat shows all objects classified as having an infrared excess
from its SDSS and UKIDSS spectral energy distribution. Finally
posqso.dat lists the objects believed to be quasars from their SDSS and
UKIDSS spectral energy distribution.
(4 data files).
[show abstract][hide abstract] ABSTRACT: We have obtained radial velocity information spanning at least two
nights from our follow-up observations of several hundred SDSS WDMS
binaries (e.g. Rebassa-Mansergas et al. 2008MNRAS.390.1635R; Schreiber
et al. 2008A&A...484..441S, 2010, Cat. J/A+A/513/L7) supplemented by
the SDSS sub-spectra (all SDSS spectra are the result of combining at
least three individual sub-exposures; see Rebassa-Mansergas et al. 2007,
Cat. J/MNRAS/382/1377, 2010, Cat. J/MNRAS/402/620).
(1 data file).
[show abstract][hide abstract] ABSTRACT: We present an updated version of the spectroscopic white dwarf-main sequence
(WDMS) binary catalogue from the Sloan Digital Sky Survey (SDSS). 395 new
systems are serendipitous discoveries from the spectroscopic SDSSI/II Legacy
targets. As part of SEGUE, we have carried out a dedicated and efficient (64
per cent success rate) search for WDMS binaries with a strong contribution of
the companion star, which were underrepresented by all previous surveys,
identifying 251 additional systems. In total, our catalogue contains 2248 WDMS
binaries, and includes, where available, magnitudes from the GALEX All Sky
Survey in the ultraviolet and from the UKIRT Infrared Sky Survey (UKIDSS) in
the near-infrared. We also provide radial velocities of the companion stars,
measured from the SDSS spectroscopy using the NaI8183.27,8194.81 absorption
doublet and/or the Halpha emission. Using an updated version of our spectral
decomposition/fitting technique we determine/update the white dwarf effective
temperatures, surface gravities and masses, as well as the spectral type of the
companion stars for the entire catalogue. Comparing the distributions of white
dwarf mass, temperature, and companion spectral type, we confirm that our SEGUE
survey project has been successful in identifying WDMS binaries with cooler and
more massive white dwarfs, as well as earlier spectral types than found
previously. Finally, we have developed a publicly available interactive on-line
data base for spectroscopic SDSS WDMS binaries containing all available stellar
parameters, radial velocities and magnitudes which we briefly describe.
Monthly Notices of the Royal Astronomical Society 10/2011; 419. · 5.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: For the survey phase of the Kepler Mission, three groups submitted
proposals containing candidate hot subdwarf and white dwarf stars. Of
the stars included in these proposals, 142 were accepted into the list
of KASC survey stars. Of these, six were observed during the 9.7d
commissioning run, and 57 were observed during the first four (out of
10) survey months. All 63 stars are listed in Table 1.
(1 data file).
[show abstract][hide abstract] ABSTRACT: For the survey phase of the Kepler Mission, three groups submitted proposals containing candidate hot subdwarf and white dwarf stars. Of the stars included in these proposals, 142 were accepted into the list of KASC survey stars. Of these, six were observed during the 9.7d commissioning run, and 57 were observed during the first four (out of 10) survey months. All 63 stars are listed in Table 1. (1 data file).
[show abstract][hide abstract] ABSTRACT: Oribital phase‐resolved spectra of EF Eri were obtained with the Solar Blind Channel on the Hubble Space Telescope during its low state. The specta peaked at 1500 and 1700 Å, and the integrated UV light curves displayed quasi‐sinusoidal modulations. WD hotspot and cyclotron emission models were computed in an attempt to fit the spectroscopic morphology throughout the orbit.
[show abstract][hide abstract] ABSTRACT: Long-slit spectroscopy (29 spectra obtained over two nights) and differential photometry (167 datapoints obtained over two nights) are presented for the cataclysmic variable SDSS J003941.06+005427.5. (3 data files).
[show abstract][hide abstract] ABSTRACT: To interpret the UVEX observations, simulations of the colours of stars and the effect of reddening are a very powerful and important tool. In obtaining the simulated colours, we follow the procedure as outlined in Drew et al. (2005MNRAS.362..753D) for the IPHAS. (6 data files).
[show abstract][hide abstract] ABSTRACT: We present VLT spectroscopy and NTT photometry of the faint cataclysmic binary SDSS J003941.06+005427.5. This object shows triple-peaked Halpha emission with all three peaks variable in both strength and velocity. We measure an orbital period of 91.395 ± 0.093 min from the velocity variations of the wings of the Halpha emission line. Using the GALEX and SDSS photometry of this object, we determine a white dwarf temperature of 15 000 K and a very late (⪆L2) spectral type for the companion star. These measurements, plus the relatively long orbital period, suggest that SDSS J003941.06+005427.5 may be a post-bounce cataclysmic variable. Doppler maps of the Halpha and He I 6678 Å emission features show an accretion disc with a non-uniform brightness and departures from Keplerian flow. The third emission peak is detected only in Halpha and at a relatively low velocity amplitude of 202 ± 3 km s-1. We are unable to explain this emission as arising from either the white dwarf, the secondary star, or the accretion disc. We tentatively attribute this mysterious central peak to a coronal loop anchored at the secondary star. If confirmed, this would be the first example of a slingshot prominence in a CV with a low mass-transfer rate and/or a fully convective secondary star. Reduced data (photometry and spectroscopy) are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or via http://cdsweb.u-strasbg.fr/viz-bin/qcat?J/A+A/524/A86
Astronomy and Astrophysics 01/2010; · 5.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: Time-resolved low resolution Hubble Space Telescope ultraviolet spectra together with ground-based optical photometry and spectra are used to constrain the temperatures and pulsation properties of six cataclysmic variables containing pulsating white dwarfs. Combining our temperature determinations for the five pulsating white dwarfs that are several years past outburst with past results on six other systems shows that the instability strip for accreting pulsating white dwarfs ranges from 10,500-15,000K, a wider range than evident for ZZ Ceti pulsators. Analysis of the UV/optical pulsation properties reveals some puzzling aspects. While half the systems show high pulsation amplitudes in the UV compared to their optical counterparts, others show UV/optical amplitude ratios that are less than one or no pulsations at either wavelength region. Comment: 19 pages, 6 tables 14 figs; accepted in ApJ
[show abstract][hide abstract] ABSTRACT: We present photometry of nine cataclysmic variable stars identified by the Sloan Digital Sky Survey, aimed at measuring the orbital periods of these systems. Four of these objects show deep eclipses, from which we measure their orbital periods. The light curves of three of the eclipsing systems are also analysed using the LCURVE code, and their mass ratios and orbital inclinations determined. SDSS J075059.97+141150.1 has an orbital period of 134.1564 +/- 0.0008 min, making it a useful object with which to investigate the evolutionary processes of cataclysmic variables. SDSS J092444.48+080150.9 has a period of 131.2432 +/- 0.0014 min and is probably magnetic. The white dwarf ingress and egress phases are very deep and short, and there is no clear evidence that this object has an accretion disc. SDSS J115207.00+404947.8 and SDSS J152419.33+220920.1 are nearly identical twins, with periods of 97.5 +/- 0.4 and 93.6 +/- 0.5 min and mass ratios of 0.14 +/- 0.03 and 0.17 +/- 0.03, respectively. Their eclipses have well-defined white dwarf and bright spot ingress and egress features, making them excellent candidates for detailed study. All four of the orbital periods presented here are shorter than the 2-3 hour period gap observed in the known population of cataclysmic variables. Comment: Accepted for publication in A&A. 9 pages, with 10 figures and 5 tables
Astronomy and Astrophysics 12/2009; · 5.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: We present time-resolved spectroscopy and photometry of SDSS J100658.40+233724.4, which we have discovered to be an eclipsing cataclysmic variable with an orbital period of 0.18591324 days (267.71507 min). The observed velocity amplitude of the secondary star is 276 +/- 7 km/s, which an irradiation correction reduces to 258 +/- 12 km/s. Doppler tomography of emission lines from the infrared calcium triplet supports this measurement. We have modelled the light curve using the LCURVE code and Markov Chain Monte Carlo simulations, finding a mass ratio of 0.51 +/- 0.08. From the velocity amplitude and the light curve analysis we find the mass of the white dwarf to be 0.78 +/- 0.12 Msun and the masses and radii of the secondary star to be 0.40 +/- 0.10 Msun and 0.466 +/- 0.036 Rsun, respectively. The secondary component is less dense than a normal main sequence star but its properties are in good agreement with the expected values for a CV of this orbital period. By modelling the spectral energy distribution of the system we find a distance of 676 +/- 40 pc and estimate a white dwarf effective temperature of 16500 +/- 2000 K. Comment: Accepted for publication in A&A. 9 pages, lots of nice figures
Astronomy and Astrophysics 09/2009; · 5.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: We present the discovery and follow-up observations of eclipses of the cataclysmic variable star SDSS J100658.40+233724.4, fom which we determine the orbital period and the masses and radii of the two stellar components. Time-resolved optical spectroscopic observations covering the full orbital period were obtained on three consecutive nights. Time-resolved photometry of four eclipses was obtained between 2008 February and December. (4 data files).
[show abstract][hide abstract] ABSTRACT: We have developed a procedure based on chi2^ template fitting in order to automatically identify WDMS binary candidates from the SDSS DR6 spectroscopic data base. (5 data files).