- ID:
- ivo://CDS.VizieR/J/ApJ/660/1556
- Title:
- Characterization of dusty debris disks
- Short Name:
- J/ApJ/660/1556
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dusty debris disks around main-sequence stars are signposts for the existence of planetesimals and exoplanets. From cross-correlating Hipparcos stars with the IRAS catalogs, we identify 146 stars within 120pc of Earth that show excess emission at 60um. This search took special precautions to avoid false positives. Our sample is reasonably well distributed from late B to early K-type stars, but it contains very few later type stars. Even though IRAS flew more than 20 years ago and many astronomers have cross-correlated its catalogs with stellar catalogs, we were still able to newly identify debris disks at as many as 33 main-sequence stars; of these, 32 are within 100pc of Earth. The power of an all-sky survey satellite like IRAS is evident when comparing our 33 new debris disks with the total of only 22 dusty debris disk stars first detected with the more sensitive, but pointed, satellite ISO. Our investigation focuses on the mass, dimensions, and evolution of dusty debris disks.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/599/A90
- Title:
- Characterization of HD 108874 system
- Short Name:
- J/A+A/599/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to understand the observed physical and orbital diversity of extrasolar planetary systems, a full investigation of these objects and of their host stars is necessary. Within this field, one of the main purposes of the GAPS observing project with HARPS-N@TNG is to provide a more detailed characterisation of already known systems. In this framework we monitored the star, hosting two giant planets, HD108874, with HARPS-N for three years in order to refine the orbits, to improve the dynamical study and to search for additional low-mass planets in close orbits. We subtracted the radial velocity (RV) signal due to the known outer planets, finding a clear modulation of 40.2d period. We analysed the correlation between RV residuals and the activity indicators and modelled the magnetic activity with a dedicated code. Our analysis suggests that the 40.2d periodicity is a signature of the rotation period of the star. A refined orbital solution is provided, revealing that the system is close to a mean motion resonance of about 9:2, in a stable configuration over 1Gyr. Stable orbits for low-mass planets are limited to regions very close to the star or far from it. Our data exclude super-Earths with Msini>~5M_{earth}_ within 0.4AU and objects with Msini>~2M_{earth}_ with orbital periods of a few days. Finally we put constraints on the habitable zone of the system, assuming the presence of an exomoon orbiting the inner giant planet.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/2274
- Title:
- Characterization of Herschel SPIRE FTS
- Short Name:
- J/MNRAS/449/2274
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A systematic programme of calibration observations was carried out to monitor the performance of the Spectral and Photometric Imaging REceiver (SPIRE) Fourier Transform Spectrometer (FTS) instrument on board the Herschel Space Observatory. Observations of planets (including the prime point-source calibrator, Uranus), asteroids, line sources, dark sky and cross-calibration sources were made in order to monitor repeatability and sensitivity, and to improve FTS calibration. We present a complete analysis of the full set of calibration observations and use them to assess the performance of the FTS. Particular care is taken to understand and separate out the effect of pointing uncertainties, including the position of the internal beam steering mirror for sparse observations in the early part of the mission. The repeatability of spectral-line centre positions is <5km/s, for lines with signal-to-noise ratios >40, corresponding to <0.5-2.0 percent of a resolution element. For spectral-line flux, the repeatability is better than 6 percent, which improves to 1-2 percent for spectra corrected for pointing offsets. The continuum repeatability is 4.4 percent for the SPIRE Long Wavelength spectrometer (SLW) band and 13.6 percent for the SPIRE Short Wavelength spectrometer (SSW) band, which reduces to ~1 percent once the data have been corrected for pointing offsets. Observations of dark sky were used to assess the sensitivity and the systematic offset in the continuum, both of which were found to be consistent across the FTS-detector arrays. The average point-source calibrated sensitivity for the centre detectors is 0.20 and 0.21Jy [1{sigma}; 1h], for SLW and SSW. The average continuum offset is 0.40Jy for the SLW band and 0.28Jy for the SSW band.
- ID:
- ivo://CDS.VizieR/J/A+A/475/1125
- Title:
- Characterization of the hot Neptune GJ 436b
- Short Name:
- J/A+A/475/1125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer Space Telescope infrared photometry of a secondary eclipse as well as ground-based photometric and spectroscopic measurements of the hot Neptune GJ 436b.
- ID:
- ivo://CDS.VizieR/J/ApJ/683/424
- Title:
- CHARA observations of 3 late-type stars
- Short Name:
- J/ApJ/683/424
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the longest baselines of the CHARA Array, we have measured the angular diameter of the G5V subdwarf {mu} Cas A, the first such determination for a halo population star. We compare this result to new diameters for the higher metallicity K0V stars, {sigma} Dra and HR 511, and find that the metal-poor star, {mu} Cas A, has an effective temperature (T_eff_=5297+/-32K), radius (R=0.791+/-0.008R_{sun}_), and absolute luminosity (L=0.442+/-0.014L_{sun}_) comparable to those of the other two stars with later spectral types. We show that stellar models show a discrepancy in the predicted temperature and radius for {mu} Cas A, and we discuss these results and how they provide a key to understanding the fundamental relationships for stars with low metallicity.
- ID:
- ivo://CDS.VizieR/J/AJ/148/48
- Title:
- CHARA obs. of omega And, HD 178911, xi Cep
- Short Name:
- J/AJ/148/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- When observed with optical long-baseline interferometers, components of a binary star that are sufficiently separated produce their own interferometric fringe packets; these are referred to as separated fringe packet (SFP) binaries. These SFP binaries can overlap in angular separation with the regime of systems resolvable by speckle interferometry at single, large-aperture telescopes and can provide additional measurements for preliminary orbits lacking good phase coverage, help constrain elements of already established orbits, and locate new binaries in the undersampled regime between the bounds of spectroscopic surveys and speckle interferometry. In this process, a visibility calibration star is not needed, and the SFPs can provide an accurate vector separation. In this paper, we apply the SFP approach to {omega} Andromeda, HD 178911, and {xi} Cephei with the CLIMB three-beam combiner at the CHARA Array. For these systems we determine component masses and parallax of 0.963+/-0.049M_{sun}_ and 0.860+/-0.051M_{sun}_ and 39.54+/-1.85mas for {omega} Andromeda, for HD 178911 of 0.802+/-0.055M_{sun}_and 0.622+/-0.053M_{sun}_with 28.26+/-1.70mas, and masses of 1.045+/-0.031M_{sun}_and 0.408+/-0.066M_{sun}_and 38.10+/-2.81mas for {xi} Cephei.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A141
- Title:
- Chariklo's system from stellar occultations
- Short Name:
- J/A+A/652/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Centaur (10199) Chariklo has the first rings system discovered around a small object. It was first observed using stellar occultation in 2013. Stellar occultations allow the determination of sizes and shapes with kilometre accuracy and obtain characteristics of the occulting object and its vicinity. Using stellar occultations observed between 2017 and 2020, we aim at constraining Chariklo's and its rings physical parameters. We also determine the rings' structure, and obtain precise astrometrical positions of Chariklo. We predicted and organised several observational campaigns of stellar occultations by Chariklo. Occultation light curves were measured from the data sets, from which ingress and egress times, and rings' width and opacity were obtained. These measurements, combined with results from previous works, allow us to obtain significant constraints on Chariklo's shape and rings' structure. We characterise Chariklo's ring system (C1R and C2R), and obtain radii and pole orientations that are consistent with, but more accurate than, results from previous occultations. We confirmed the detection of W-shaped structures within C1R and an evident variation of radial width. The observed width ranges between 4.8 and 9.1km with a mean value of 6.5km. One dual observation (visible and red) does not reveal any differences in the C1R opacity profiles, indicating ring particle's size larger than a few microns. The C1R ring eccentricity is found to be smaller than 0.022 (3-sigma), and its width variations may indicate an eccentricity higher than 0.005. We fit a tri-axial shape to Chariklo's detections over eleven occultations and determine that Chariklo is consistent with an ellipsoid with semi-axes of 143.8, 135.2 and 99.1km. Ultimately, we provided seven astrometric positions at a milliarcseconds accuracy level, based on Gaia EDR3, and use it to improve Chariklo's ephemeris.
- ID:
- ivo://CDS.VizieR/J/AJ/119/2008
- Title:
- 10199 Chariklo stellar occultation: 1999-2005
- Short Name:
- J/AJ/119/2008
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Flagstaff Astrometric Scanning Transit Telescope was used to scan the sky in search of occultation candidates through which the Centaur 10199 Chariklo (formerly 1997 CU_26_) will pass in 1999-2005. Positions for 96,397 stars (magnitudes 7.5<V<17.3) were determined using differential reductions to the ACT catalog of star positions and proper motions, and accuracies of +/-30mas were achieved for well-exposed images. The ephemeris for 10199 Chariklo was improved by including the new positions presented in this paper and, second, by correcting older positions taken from the literature for systematic errors. During this time period, 10199 Chariklo passes within 2" of 117 of these stars, which are identified as occultation candidates in this paper. Among these, 28 candidates have magnitudes V<15.0, making them the best choices for observing programs using portable telescopes. Circumstances for each occultation are given. Because the angular radius of 10199 Chariklo is only about 15mas, the astrometry provided in this paper is only accurate enough for identifying possible occultation events and is not sufficient for predicting individual shadow paths across the surface of Earth, although representative cases are given. Last-minute astrometry with a large-aperture telescope will be needed to refine each prediction.
- ID:
- ivo://CDS.VizieR/J/A+A/431/773
- Title:
- CHARM2, an updated of CHARM catalog
- Short Name:
- J/A+A/431/773
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an update of the Catalog of High Angular Resolution Measurements (CHARM, Richichi & Percheron, 2002, Cat. <J/A+A/386/492>), which includes results available until July 2004. CHARM2 is a compilation of direct measurements by high angular resolution methods, as well as indirect estimates of stellar diameters. Its main goal is to provide a reference list of sources which can be used for calibration and verification observations with long-baseline optical and near-IR interferometers. Single and binary stars are included, as are complex objects from circumstellar shells to extragalactic sources. The present update provides an increase of almost a factor of two over the previous edition. Additionally, it includes several corrections and improvements, as well as a cross-check with the valuable public release observations of the ESO Very Large Telescope Interferometer (VLTI). A total of 8231 entries for 3238 unique sources are now present in CHARM2. This represents an increase of a factor of 3.4 and 2.0, respectively, over the contents of the previous version of CHARM.
- ID:
- ivo://CDS.VizieR/J/A+AS/114/109
- Title:
- Cha X-ray sources & optical identifications
- Short Name:
- J/A+AS/114/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the observations of the ROSAT all-sky survey (RASS) in the direction of the Chamaeleon cloud complex, as well as the spectroscopic identifications of the detected X-ray sources. The main purpose of this identification program was the search for low mass pre-main sequence stars. Sixteen previously known PMS stars were detected with high confidence by ROSAT. Eight are classical T Tauri stars and eight are weak-line T Tauri stars. Seventy-seven new weak-line T Tauri stars were identified on the basis of the presence of strong Li {lambda}6707 absorption, spectral type later than F0 and chromospheric emission. We give coordinates and count rates of the X-ray sources, and present optical spectra and finding charts for the sources identified optically as new pre-main sequence stars. Optical UBV(RI)c and near-infrared JHKLM photometry for this sample of stars is also provided. In addition, 6 new dKe-dMe candidates are found among the RASS sources.
