Search results for "Optical astronomy"
showing 10 items of 23 documents
Mapping accretion variability in NGC 2264
2014
Our study aims at characterizing the accretion properties of several hundred members of the star-forming region NGC 2264 (3Myr). We performed a deep u,g,r,i mapping of the cluster with CFHT/MegaCam, and monitored the simultaneous u+r variability of its members over a baseline of two weeks. Stellar parameters are determined homogeneously for about 750 monitored young objects, 40% of which are accreting T Tauri stars. Accretion properties and accretion variability are investigated and characterized from UV excess measurements. Non-accreting members of the cluster define the reference UV emission level over which flux excess is detected and measured. Cone search capability for table J/A+A/570/…
CIG 96 deep optical and HI images
2018
Asymmetries in atomic hydrogen (HI) in galaxies are often caused by the interaction with close companions, making isolated galaxies an ideal framework to study secular evolution. The AMIGA project has demonstrated that isolated galaxies show the lowest level of asymmetry in their HI integrated profiles compared to even field galaxies, yet some present significant asymmetries. CIG 96 (NGC 864) is a representative case reaching a 16% level. Our aim is to investigate the HI asymmetries of the spiral galaxy CIG 96 and what processes have triggered the star-forming regions observed in the XUV pseudo-ring. We performed deep optical observations at CAHA1.23m, CAHA2.2m and VST (OmegaCAM wide-field …
The TESS Grand Unified Hot Jupiter Survey I. 10 planets
2022
Hot Jupiters-short-period giant planets-were the first extrasolar planets to be discovered, but many questions about their origin remain. NASA's Transiting Exoplanet Survey Satellite (TESS), an all-sky search for transiting planets, presents an opportunity to address these questions by constructing a uniform sample of hot Jupiters for demographic study through new detections and unifying the work of previous ground-based transit surveys. As the first results of an effort to build this large sample of planets, we report here the discovery of 10 new hot Jupiters (TOI-2193Ab, TOI-2207b, TOI-2236b, TOI-2421b, TOI-2567b, TOI-2570b, TOI-3331b, TOI-3540Ab, TOI-3693b, TOI-4137b). All of the planets…
HAQ survey: red QSO candidates follow-up
2015
Quasi-stellar objects (QSOs) whose spectral energy distributions (SEDs) are reddened by dust either in their host galaxies or in intervening absorber galaxies are to a large degree missed by optical color selection criteria like the ones used by the Sloan Digital Sky Survey (SDSS). To overcome this bias against red QSOs, we employ a combined optical and near-infrared (near-IR) color selection. In this paper, we present a spectroscopic follow-up campaign of a sample of red candidate QSOs which were selected from the SDSS and the UKIRT Infrared Deep Sky Survey (UKIDSS). The spectroscopic data and SDSS/UKIDSS photometry are supplemented by mid-infrared photometry from the Wide-field Infrared S…
UV variability and accretion in NGC 2264
2015
Photometric variability is a distinctive feature of young stellar objects; exploring variability signatures at different wavelengths provides insight into the physical processes at work in these sources. We explore the variability signatures at ultraviolet (UV) and optical wavelengths for several hundred accreting and non-accreting members of the star-forming region NGC 2264 (~3Myr). Cone search capability for table J/A+A/581/A66/table2 (Median photometry, variability amplitudes, light curve rms, J index, and color slopes for members monitored at CFHT)
Variability in proto-PNe. II.
2014
We have carried out a detailed observational study of the light, color, and velocity variations of two bright, carbon-rich proto-planetary nebulae, IRAS 22223+4327 and 22272+5435. The light curves are based upon our observations from 1994 to 2011, together with published data by Arkhipova and collaborators. They each display four significant periods, with primary periods for IRAS 22223+4327 and 22272+5435 being 90 and 132 days, respectively. For each of them, the ratio of secondary to primary period is 0.95, a value much different from that found in Cepheids, but which may be characteristic of post-asymptotic giant branch (AGB) stars. Fewer significant periods are found in the smaller radia…
Radio-optical scrutiny of compact AGN
2010
We study the correlations between the VLBA (Very Long Baseline Array) radio emission at 15GHz, extended emission at 151MHz, and optical nuclear emission at 5100{AA} for a complete sample of 135 compact jets. We use the partial Kendall's tau correlation analysis to check the link between radio properties of parsec-scale jets and optical nuclear luminosities of host active galactic nuclei (AGN). Cone search capability for table J/A+A/520/A62/table3 (Optical and radio parameters of 135 AGN)
Gaia-ESO Survey: Li-rich stars in NGC2547
2015
The nearby (distance ~350-400pc), rich Vela OB2 association, includes gamma^2^ Velorum, one of the most massive binaries in the solar neighborhood, and is an excellent laboratory for investigating the formation and early evolution of young clusters. Recent Gaia-ESO survey observations led to the discovery of two kinematically distinct populations in the young (10-15Myr) cluster immediately surrounding gamma^2^ Velorum. Here we analyse the results of Gaia-ESO survey observations of NGC 2547, a 35Myr cluster located two degrees south of gamma^2^ Velorum. The radial velocity distribution of lithium-rich pre-main sequence stars shows a secondary population, kinematically distinct and younger th…
Photometry of candidate members of NGC6611
2009
We present the list of candidate members of the young open cluster NGC 6611, selected in a field of view of 33'x34' by the X-rays emission and excesses in infrared bands. X-ray sources without infrared excesses are classified as candidate Class III cluster members; stars with infrared excesses as disk bearing members. Cone search capability for table J/A+A/496/453/catalog (NGC 6611 cluster member positions and magnitudes)
uvby{beta} photometry of h and chi Per
2002
We present CCD uvby{beta} photometry for stars in the nuclei of the young double cluster {h} and {chi} Persei. We find that the reddening is highly variable through the {h} Per nucleus, increasing from west to east, with values ranging from E(b-y)=0.328+/-0.022 in the western part to E(b-y)=0.465+/-0.025 in the south-east. Towards {chi} Persei the reddening is fairly constant, with E(b-y)=0.398+/-0.025. Both clusters share a common distance modulus of 11.7+/-0.1mag, and an age of logt=7.10+/-0.05 years. Cone search capability for table J/A+A/394/479/table6 (Coordinates and photometry for stars in h Per) Cone search capability for table J/A+A/394/479/table7 (Coordinates and photometry for st…