We report on multi-band photometric observations of four binary millisecond pulsars with the Gran Telescopio Canarias. The observations led to detection of binary companions to PSRs J1630+3734, J1741+1351 and J2042+0246 in the Sloan g', r' and i' bands. Their magnitudes in the r' band are $\approx$24.4, 24.4 and 24.0, respectively. We also set a 3$σ$ upper limit on the brightness of the PSR J0557+1550 companion in the r' band of $\approx$25.6 mag. Combining the optical data with the radio timing measurements and white dwarf cooling models, we show that the detected companions are cool low-mass white dwarfs with temperatures and ages in the respective ranges of (4-7)$\times 10^3$ K and 2-5 Gyr. All the detected white dwarfs are found to likely have either pure hydrogen or mixed helium-hydrogen atmospheres.
We report detection of the binary companion to the millisecond pulsar J1741+1351 with the Gran Telescopio Canarias. The optical source position coincides with the pulsar coordinates and its magnitudes are g' = 24.84(5), r' = 24.38(4) and i' = 24.17(4). Comparison of the data with the white dwarf evolutionary models shows that the source can be a He-core white dwarf with a temperature of $\approx 6000$ K and a mass of $\approx 0.2$ M$_{\odot}$. The latter is in excellent agreement with the companion mass obtained from the radio timing solution for PSR J1741+1351.
We report detection of the binary companion to the millisecond pulsar J2302+4442 based on the deep observations performed with the Gran Telescopio Canarias. The observations revealed an optical source with $r'$ = 23.33$\pm$0.02 and $i'$=23.08$\pm$0.02, whose position coincides with the pulsar radio position. By comparing the source colour and magnitudes with the white dwarf cooling predictions, we found that it likely represents a He or CO-core white dwarf and estimated its mass of 0.52$^{+0.25}_{-0.19}$ M$_{\odot}$ and effective temperature of 6300$^{+1000}_{-800}$ K. Combining our results wi…
We present the first release of GTC OSIRIS Broad Band data archive. This is an effort conducted in the framework of the Spanish Virtual Observatory to help optimize science from the Gran Telescopio Canarias Archive. Data Release 1 includes 6 788 broad-band images in the Sloan griz filters obtained between April 2009 and January 2014 and the associated catalogue with roughly 6.23 million detections of more than 630 000 unique sources. The catalogue contains standard PSF and Kron aperture photometry with a mean accuracy better than 0.09 and 0.15 mag, respectively. The relative astrometric residu…
We report the discovery of the carbon-rich ultra metal-poor unevolved star J0815+4729. This dwarf star was selected from SDSS/BOSS as a metal-poor candidate and follow-up spectroscopic observations at medium-resolution were obtained with ISIS at William Herschel Telescope and OSIRIS at Gran Telescopio de Canarias. We use the FERRE code to derive the main stellar parameters, Teff=6215+-82 K, and logg=4.7+-0.5, an upper limit to the metallicity of [Fe/H]<~-5.8, and a carbon abundance of [C/Fe]>~+5.0, while [alpha/Fe]=0.4 is assumed. The metallicity upper limit is based on the Ca II K line, that …
We report observations of HD 80606 using the 10.4-m Gran Telescopio Canarias (GTC) and the OSIRIS tunable filter imager. We acquired very-high-precision, narrow-band photometry in four bandpasses around the K I absorption feature during the January 2010 transit of HD 80606b and during out-of-transit observations conducted in January and April of 2010. We obtained differential photometric precisions of \sim 2.08e-4 for the in-transit flux ratio measured at 769.91-nm, which probes the K I line core. We find no significant difference in the in-transit flux ratio between observations at 768.76 and…
We report the detection of the likely companion of the binary millisecond pulsar J0740+6620 with the Gran Telescopio Canarias in the $r'$ and $i'$ bands. The position of the detected starlike source coincides with the pulsar coordinates within the 1$σ$ uncertainty of $\approx$ 0.2 arcsec. Its magnitudes are $r'=26.51\pm0.17$ and $i'=25.49\pm0.15$. Comparing the data with the white dwarf cooling tracks suggests that it can be an ultracool helium-atmosphere white dwarf with the temperature $\lesssim$ 3500 K and cooling age $\gtrsim$ 5 Gyr. The age is consistent with the pulsar characteristic age…
We present the results of low-resolution optical spectroscopy with OSIRIS/GTC (Optical System for Imaging and Low Resolution Integrated Spectroscopy / Gran Telescopio Canarias) for a sample of ultracool dwarfs. For a subsample of seven objects, based on 2MASS NIR photometric colours, a 'photometric' spectral type is determined and compared to the results of the optical spectroscopy. For the stars, showing H$α$ line in emission, equivalent widths were measured, and the ratio of H$α$ to bolometric luminosity were calculated. We find that two dwarfs show the presence of magnetic activity over lon…
We present an optical (gri) study during quiescence of the accreting millisecond X-ray pulsar IGR J00291+5934 performed with the 10.4m Gran Telescopio Canarias (GTC) in August 2014. Despite the source being in quiescence at the time of our observations, it showed a strong optical flaring activity, more pronounced at higher frequencies (i.e. the g band). Once the flares were subtracted, we tentatively recovered a sinusoidal modulation at the system orbital period in all bands, even if a significant phase shift with respect to an irradiated star, typical of accreting millisecond X-ray pulsars is…
We have obtained a low-resolution optical spectrum for one of the faintest cluster member candidates in Praesepe with the Optical System for Imaging and low Resolution Integrated Spectroscopy mounted on the 10.4m Gran Telescopio de Canarias. We confirm spectroscopically the first L dwarf member in Praesepe, UGCS J084510.66+214817.1. We derived an optical spectral type of L0.3+/-0.4 and estimated its effective temperature to Teff=2279+/-371 K and a mass of 71.1+/-23.0M_Jup, according to state-of-the-art models, placing it at the hydrogen-burning boundary. We measured the equivalent width of the…
The aim of this work is confirming the optical identification of PSR B1133+16, whose candidate optical counterpart was detected in Very Large Telescope (VLT) images obtained back in 2003. We used new deep optical images of the PSR B1133+16 field obtained with both the 10.4 m Gran Telescopio Canarias (GTC) and the VLT in the g' and B bands, respectively, to confirm the detection of its candidate optical counterpart and its coincidence with the most recent pulsar's radio coordinates. We did not detect any object at the position of the pulsar candidate counterpart (B~28), measured in our 2003 VLT…
The aim of the project is to contribute to the characterisation of the spectral energy distribution of the coolest brown dwarfs discovered to date, the Y dwarfs. We obtained z-band far-red imaging for six Y dwarfs and a T9+Y0 binary with the OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy) instrument on the 10.4-m Gran Telescopio de Canarias (GTC). We detect five of the seven known Y dwarfs in the $z$-band, infer their optical-to-infrared colours, and measure their proper motions. We find a higher dispersion in the z-J and z-H colours of Y0 dwarfs than in T dwarfs…
We present results from a global view on the colliding-wind binary WR 147. We analysed new optical spectra of WR 147 obtained with Gran Telescopio CANARIAS and archive spectra from the Hubble Space Telescope by making use of modern atmosphere models accounting for optically thin clumping. We adopted a grid-modelling approach to derive some basic physical characteristics of both stellar components in WR 147. For the currently accepted distance of 630 pc to WR 147, the values of mass-loss rate derived from modelling its optical spectra are in acceptable correspondence with that from modelling it…
We present optical photometry of the cataclysmic variable LAMOST J024048.51+195226.9 taken with the high-speed, five-band CCD camera HiPERCAM on the 10.4 m Gran Telescopio Canarias (GTC). We detect pulsations originating from the spin of its white dwarf, finding a spin period of 24.9328(38)s. The pulse amplitude is of the order of 0.2% in the g-band, below the detection limits of previous searches. This detection establishes LAMOST J024048.51+195226.9 as only the second white dwarf magnetic propeller system, a twin of its long-known predecessor, AE Aquarii. At 24.93s, the white dwarf in LAMOST…
We report the discovery of an esdL3 subdwarf, ULAS J020858.62+020657.0, and a usdL4.5 subdwarf, ULAS J230711.01+014447.1. They were identified as L subdwarfs by optical spectra obtained with the Gran Telescopio Canarias, and followed up by optical-to-near-infrared spectroscopy with the Very Large Telescope. We also obtained an optical-to-near-infrared spectrum of a previously known L subdwarf, ULAS J135058.85+081506.8, and reclassified it as a usdL3 subdwarf. These three objects all have typical halo kinematics. They have $T_{\rm eff}$ around 2050$-$2250 K, $-$1.8 $\leq$ [Fe/H] $\leq -$1.5, an…
We present 27 new L subdwarfs and classify five of them as esdL and 22 as sdL. Our L subdwarf candidates were selected with the UKIRT Infrared Deep Sky Survey and Sloan Digital Sky Survey. Spectroscopic follow-up was carried out primarily with the OSIRIS spectrograph on the Gran Telescopio Canarias. Some of these new objects were followed up with the X-shooter instrument on the Very Large Telescope. We studied the photometric properties of the population of known L subdwarfs using colour-spectral type diagrams and colour-colour diagrams, by comparison with L dwarfs and main-sequence stars, and…
Context. Although many studies have been performed so far, there are still dozens of low-mass stars and brown dwarfs in the young sigma Orionis open cluster without detailed spectroscopic characterisation. Aims. We look for unknown strong accretors and disc hosts that were undetected in previous surveys. Methods. We collected low-resolution spectroscopy (R ~ 700) of ten low-mass stars and brown dwarfs in sigma Orionis with OSIRIS at the Gran Telescopio Canarias under very poor weather conditions. These objects display variability in the optical, infrared, Halpha, and/or X-rays on time scales o…
K 1-6 is a photoionised ISM nebula shaped by a fast-moving hot white dwarf in a triple system
Astronomical Institute of Charles University（查理大学天文研究所）；Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）；Departamento de Astrofísica, Universidad de La Laguna（拉帕尔马拉古纳大学天体物理学系）；European Southern Observatory（欧洲南方天文台）；Landessternwarte Heidelberg, Zentrum für Astronomie, Ruprecht-Karls-Universität（海德堡州立天文台，海德堡大学天文学中心）
In this work we present the results of a direct imaging survey for brown dwarf companions around the nearest stars at the mid-infrared 10 micron range ($λ_{c}$=8.7$μ$m, $Δλ$=1.1$μ$m) using the CanariCam instrument at the 10.4 m Gran Telescopio Canarias (GTC). We imaged the 25 nearest stellar systems within 5 pc of the Sun at declinations $δ> -25^{\circ}$ (at least half have planets from radial velocity), reaching a mean detection limit of 11.3$\pm$0.2 mag (1.5 mJy) in the Si-2 8.7$μ$m band over a range of angular separations from 1 to 10 arcsec. This would have allowed us to uncover substellar…
