CFHT Corporation

HI, United States

CFHT Corporation

HI, United States
Time filter
Source Type

Donati J.-F.,Toulouse 1 University Capitole | Donati J.-F.,CNRS Astrophysics and Planetology Research Institute | Yu L.,Toulouse 1 University Capitole | Yu L.,CNRS Astrophysics and Planetology Research Institute | And 19 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2017

We report results of an extended spectropolarimetric and photometric monitoring of the weakline T Tauri star V830 Tau and its recently detected newborn close-in giant planet. Our observations, carried out within the MaTYSSE (Magnetic Topologies of Young Stars and the Survival of close-in giant Exoplanets) programme, were spread over 91 d, and involved the ESPaDOnS and Narval spectropolarimeters linked to the 3.6-m Canada-France-Hawaii, the 2-m Bernard Lyot, and the 8-m Gemini-North Telescopes. Using Zeeman-Doppler Imaging, we characterize the surface brightness distributions, magnetic topologies, and surface differential rotation of V830 Tau at the time of our observations, and demonstrate that both distributions evolve with time beyond what is expected from differential rotation. We also report that near the end of our observations, V830 Tau triggered one major flare and two weaker precursors, showing up as enhanced redshifted emission in multiple spectral activity proxies. With three different filtering techniques, we model the radial velocity (RV) activity jitter (of semi-amplitude 1.2 km s-1) that V830 Tau generates, successfully retrieve the 68 ± 11 m s-1 RV planet signal hiding behind the jitter, further confirm the existence of V830 Tau b, and better characterize its orbital parameters. We find that the method based on Gaussian-process regression performs best thanks to its higher ability at modelling not only the activity jitter, but also its temporal evolution over the course of our observations, and succeeds at reproducing our RV data down to an rms precision of 35 m s-1. Our result provides new observational constraints on scenarios of star/planet formation and demonstrates the scientific potential of large-scale searches for close-in giant planets around T Tauri stars. © 2016 The Authors.

Arrigoni Battaia F.,Max Planck Institute for Astronomy | Arrigoni Battaia F.,University of Milan Bicocca | Gavazzi G.,University of Milan Bicocca | Fumagalli M.,University of California at Santa Cruz | And 17 more authors.
Astronomy and Astrophysics | Year: 2012

Context. We study the peculiar interacting galaxy system of VCC 1249/M 49 located in the core of the Virgo B subcluster. Owing to a recent interaction between the dwarf galaxy VCC 1249 and the halo gas of the elliptical galaxy M 49, neutral hydrogen has been displaced from the interstellar medium of this dwarf into the Virgo intracluster medium. Observations also reveal multiple compact star-forming regions (aka H ii regions) that are embedded in this H i cloud, with a projected separation up to 13 kpc from VCC 1249 in the northwest direction. Aims. Motivated by recent near-ultraviolet imaging from the GALEX Ultraviolet Virgo Cluster Survey (GUViCS) of the VCC 1249/M 49 system that shows significant ongoing/recent star formation in the compact regions, we aim to constrain the origin of these outlying H ii regions with a multi-wavelength approach. Methods. Using deep optical (u,g,i,z) imaging from the Next Generation Virgo Cluster Survey (NGVS) and new Hα imaging obtained at the San Pedro Martir observatory together with Keck long-slit spectroscopy, we characterize the star formation rates, ages, and metallicity of VCC 1249 and its outlying compact regions. Moreover, we analyze the color and luminosity profile of the galaxy to investigate its recent interaction with M 49. Results. Our new observations indicate that VCC 1249 underwent a recent interaction with M 49 in which both ram-pressure stripping and tidal interaction occured. The joint action of the two mechanisms led to the removal of the H i gas from the interstellar medium of VCC 1249, while the gravitational tides triggered the stellar tail and counter-tail of VCC 1249. Our stellar population synthesis analysis reveals that the star formation in this galaxy was truncated around 200 Myr ago and that the outlying H ii regions were born in situ 10 Myr ago out of pre-enriched gas removed from the dwarf galaxy. These observations also reveal that interactions between central and satellite galaxies similar to those between VCC 1249/M 49 may be an effective way of dispersing metals into the halos of massive galaxies. © 2012 ESO.

Miroshnichenko A.S.,University of North Carolina at Greensboro | Zharikov S.V.,National Autonomous University of Mexico | Danford S.,University of North Carolina at Greensboro | Manset N.,CFHT Corporation | And 8 more authors.
Astrophysical Journal | Year: 2015

We report the results of a long-term spectroscopic monitoring of the FS CMa type object MWC 728. We found that it is a binary system with a B5 ve ( = 14,000 ± 1000 K) primary and a G8 iii type ( 5000 K) secondary. Absorption line positions of the secondary vary, with a semi-amplitude of ∼20 km s-1 and a period of 27.5 days. The system's mass function is 2.3 × 10-2 , and its orbital plane is ∼13°-15° tilted from the plane of the sky. The primary's km s-1, combined with this tilt, implies that it rotates at a nearly breakup velocity. We detected strong variations of the Balmer and He i emission-line profiles on timescales from days to years. This points to a variable stellar wind of the primary in addition to the presence of a circum-primary gaseous disk. The strength of the absorption-line spectrum, along with the optical and near infrared (IR) continuum, suggest that the primary contributes ∼60% of the V-band flux, the disk contributes ∼30%, and the secondary contributes ∼10%. The system parameters, along with the interstellar extinction, suggest a distance of ∼1 kpc, that the secondary does not fill its Roche lobe, and that the companions' mass ratio is 0.5. Overall, the observed spectral variability and the presence of a strong IR-excess are in agreement with a model of a close binary system that has undergone a non-conservative mass-transfer. © 2015. The American Astronomical Society. All rights reserved..

Miroshnichenko A.S.,University of North Carolina at Greensboro | Pasechnik A.V.,University of Turku | Manset N.,CFHT Corporation | Carciofi A.C.,University of Sao Paulo | And 19 more authors.
Astrophysical Journal | Year: 2013

We describe the results of the world-wide observing campaign of the highly eccentric Be binary system δ Scorpii 2011 periastron passage which involved professional and amateur astronomers. Our spectroscopic observations provided a precise measurement of the system orbital period at 10.8092 ± 0.0005 yr. Fitting of the He II 4686 Å line radial velocity curve determined the periastron passage time on 2011 July 3, UT 9:20 with a 0.9-day uncertainty. Both these results are in a very good agreement with recent findings from interferometry. We also derived new evolutionary masses of the binary components (13 and 8.2 M⊙) and a new distance of 136 pc from the Sun, consistent with the HIPPARCOS parallax. The radial velocity and profile variations observed in the Hα line near the 2011 periastron reflected the interaction of the secondary component and the circumstellar disk around the primary component. Using these data, we estimated a disk radius of 150 R⊙. Our analysis of the radial velocity variations measured during the periastron passage time in 2000 and 2011 along with those measured during the 20th century, the high eccentricity of the system, and the presence of a bow shock-like structure around it suggest that δ Sco might be a runaway triple system. The third component should be external to the known binary and move on an elliptical orbit that is tilted by at least 40° with respect to the binary orbital plane for such a system to be stable and responsible for the observed long-term radial velocity variations. © 2013. The American Astronomical Society. All rights reserved.

Arnold L.,Aix - Marseille University | Ehrenreich D.,Observatoire de Geneva | Vidal-Madjar A.,University Pierre and Marie Curie | Dumusque X.,Harvard - Smithsonian Center for Astrophysics | And 10 more authors.
Astronomy and Astrophysics | Year: 2014

Context. The atmospheric composition of transiting exoplanets can be characterized during transit by spectroscopy. Detections of several chemical species have previously been reported in the atmosphere of gaseous giant exoplanets. For the transit of an Earth twin, models predict that biogenic oxygen (O2) and ozone (O3) atmospheric gases should be detectable, as well as water vapour (H2O), a molecule linked to habitability as we know it on Earth. Aims. The aim is to measure the Earth radius versus wavelength λ-or the atmosphere thickness h(λ)-at the highest spectral resolution available to fully characterize the signature of Earth seen as a transiting exoplanet. Methods. We present observations of the Moon eclipse of December 21, 2010. Seen from the Moon, the Earth eclipses the Sun and opens access to the Earth atmosphere transmission spectrum. We used two different ESO spectrographs (HARPS and UVES) to take penumbra and umbra high-resolution spectra from 3100 to 10 400 Å. A change of the quantity of water vapour above the telescope compromised the quality of the UVES data. We corrected for this effect in the data processing. We analyzed the data by three different methods. The first method is based on the analysis of pairs of penumbra spectra. The second makes use of a single penumbra spectrum, and the third of all penumbra and umbra spectra. Results. Profiles h(λ) are obtained with the three methods for both instruments. The first method gives the best result, in agreement with a model. The second method seems to be more sensitive to the Doppler shift of solar spectral lines with respect to the telluric lines. The third method makes use of umbra spectra, which bias the result by increasing the overall negative slope of h(λ). It can be corrected for this a posteriori from results with the first method. The three methods clearly show the spectral signature of the Rayleigh scattering in the Earth atmosphere and the bands of H2O, O2, and O 3. Sodium is detected. Assuming no atmospheric perturbations, we show that the E-ELT is theoretically able to detect the O2A-band in 8 h of integration for an Earth twin at 10 pc. Conclusions. Biogenic O2, O3, and water vapour are detected in Earth observed as a transiting planet, and, in principle, would be within reach of the E-ELT for an Earth twin at 10 pc. © 2014 ESO.

Melis C.,University of California at Los Angeles | Melis C.,University of California at San Diego | Jura M.,University of California at Los Angeles | Albert L.,CFHT Corporation | And 2 more authors.
Astrophysical Journal | Year: 2010

We have performed a comprehensive ground-based observational program aimed at characterizing the circumstellar material orbiting three single white dwarf stars previously known to possess gaseous disks. Near-infrared imaging unambiguously detects excess infrared emission toward Ton 345 and allows us to refine models for the circumstellar dust around two of the three white dwarf stars. We find that each white dwarf hosts gaseous and dusty disks that are roughly spatially coincident, a result that is consistent with a scenario in which dusty and gaseous material has its origin in remnant parent bodies of the white dwarfs' planetary systems. We briefly describe a new model for the gas disk heating mechanism in which the gaseous material behaves like a "Z ii" region. In this Zii region, gas primarily composed of metals is photoionized by ultraviolet light and cools through optically thick allowed Ca ii-line emission. © 2010. The American Astronomical Society.

Szeto K.,National Research Council Canada | Vogiatzis K.,TMT Observatory Corporation | Hangan H.,WindEEE Research Institute | Jubayer C.M.,WindEEE Research Institute | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

The Maunakea Spectroscopic Explorer (MSE; formerly Next Generation Canada-France-Hawaii Telescope) is a dedicated, 10m aperture, wide-field, fiber-fed multi-object spectroscopic facility proposed as an upgrade to the existing Canada-France-Hawaii Telescope on the summit of Mauna Kea. The enclosure vent configuration design study is the last of three studies to examine the technical feasibility of the proposed MSE baseline concept. The enclosure vent configuration study compares the aero-thermal performance of three enclosure ventilation configurations based on the predicted dome thermal seeing and air flow attenuation over the enclosure aperture opening of a Calotte design derived from computational fluid dynamics simulations. In addition, functional and operation considerations such as access and servicing of the three ventilation configurations is discussed. © 2014 SPIE.

Vigan A.,Aix - Marseille University | Langlois M.,University of Lyon | Dohlen K.,Aix - Marseille University | Zurlo A.,Aix - Marseille University | And 8 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

The near-infrared imager and spectrograph IRDIS is one of the three science sub-systems of VLT/SPHERE dedicated to the detection and characterization of giant exoplanets at large orbital radii. It offers a wide range of observational modes including dual-band imaging (DBI) with very low differential aberrations, and long slit spectroscopy (LSS) coupled with a classical Lyot coronagraph at low (R = ∼50) and medium (R = ∼330) resolution. Over the course of 2012 and 2013, IRDIS has been extensively tested in laboratory during the integration and optimization of the SPHERE system. At the beginning of 2014, the instrument has been shipped to Chile and has been reintegrated at the Paranal observatory. We present here a detailed summary of the performance of the DBI and LSS modes obtained in laboratory. We provide a wide range of results covering different observing conditions and setups for the DBI mode, and we show that the instrument reaches the technical specifications in terms of contrast. We also identify some of the limitations that prevent going down much further in contrast while testing in the laboratory. For the LSS mode, we present results obtained both at low and medium resolution in the main setups that will be offered to future users. We demonstrate that the LSS mode will provide a useful characterization tool for the planets detected in DBI mode. Finally, we present the first results obtained on-sky during the first commissioning run of SPHERE at the VLT. © 2014 SPIE.

Evans C.,COMDEV International Ltd. | Lin H.,COMDEV International Ltd. | McColgan A.,COMDEV International Ltd. | Rowlands N.,COMDEV International Ltd. | Salmon D.,CFHT Corporation
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

The 'IMAKA (Imaging from MAuna KeA) instrument is a wide field visible light imager incorporating Ground Layer Adaptive Optics (GLAO) to take maximum advantage of the excellent seeing available at the Canada-France-Hawaii Telescope (CFHT). It requires better than 0.3″ image quality simultaneously over a total field of view of approximately one square degree (∼3 × 10-4 sr). This requirement along with other criterions and constraints raises a challenge for optical design. The advent of orthogonal transfer (OT) CCDs allows the tip-tilt portion of the atmospheric correction to be performed at the science detector itself. 'IMAKA will take full advantage of the large array mosaics of OTCCDs. Since the size of the adaptive mirror would drive the cost and hence implementation of the overall 'IMAKA instrument, a review of possible optical design configurations which minimize the size (diameter) of the deformable mirror is undertaken. A promising design was obtained and developed in more detail. This all reflective system is described along with its predicted optical performance. An opto-mechanical design concept was developed around this nominal optical design which takes into account various constraints due to its required location on the top end of the Canada France Hawaii Telescope. The design concept is feasible and meets the optical performance requirements. © 2010 Copyright SPIE - The International Society for Optical Engineering.

McConnachie A.,Herzberg Institute for Astrophysics | Cote P.,Herzberg Institute for Astrophysics | Crampton D.,Herzberg Institute for Astrophysics | Devost D.,CFHT Corporation | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

A concept study is underway to upgrade the existing 3.6 meter Canada-France-Hawaii Telescope (CFHT) to a 10 meter class, wide-field, dedicated, spectroscopic facility, which will be the sole astronomical resource capable of obtaining deep, spectroscopic follow-up data to the wealth of photometric and astrometric surveys planned for the next decade, and which is designed to tackle driving science questions on the formation of the Milky Way galaxy and the characterization and nature of dark energy. This unique facility will operate at low (R ∼ 2000), intermediate (R ∼ 6000) and high (R ∼ 20000) resolutions over the wavelength range 370 ≤ λ ≤ 1300nm, and will obtain up to 3200 simultaneous spectra per pointing over a 1.5 square degree field. Unlike all other proposed or planned wide field spectroscopic facilities, this "Next Generation CFHT" will combine the power of a 10m aperture with exquisite observing conditions and a mandate for dedicated spectroscopic studies to enable transformative science programs in fields as diverse as exoplanetary host characterization, the interstellar medium, stars and stellar astrophysics, the Milky Way galaxy, the Local Group, nearby galaxies and clusters, galaxy evolution, the inter-galactic medium, dark energy and cosmology. A new collaboration must be formed to make this necessary facility into a reality, and currently nearly 60 scientists from 11 different communities - Australia, Brazil, Canada, China, France, Hawaii, India, Japan, South Korea, Taiwan, USA - are involved in defining the science requirements and survey strategies. Here, we discuss the origins of this project, its motivations, the key science and its flow-down requirements. An accompanying article describes the technical studies completed to date. The final concept study will be submitted to the CFHT Board and Science Advisory Committee in Fall 2012, with first light for the facility aiming to be in the early 2020s. © 2012 SPIE.

Loading CFHT Corporation collaborators
Loading CFHT Corporation collaborators