- ID:
- ivo://CDS.VizieR/J/A+A/643/A112
- Title:
- CARMENES VIS RVs of 3 M dwarfs
- Short Name:
- J/A+A/643/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We announce the discovery of two planets orbiting the M dwarfs GJ 251 (0.360+/-0.015M_{sun}_) and HD 238090 (0.578+/-0.021M_{sun}_) based on CARMENES radial velocity (RV) data. In addition, we independently confirm with CARMENES data the existence of Lalande 21185 b, a planet that has recently been discovered with the SOPHIE spectrograph. All three planets belong to the class of warm or temperate super-Earths and share similar properties. The orbital periods are 14.24d, 13.67d, and 12.95d and the minimum masses are 4.0+/-0.4M_{sun}_, 6.9+/-0.9M_{sun}_, and 2.7+/-0.3M_{sun}_ for GJ 251 b, HD 238090 b, and Lalande 21185 b, respectively. Based on the orbital and stellar properties, we estimate equilibrium temperatures of 351.0+/-1.4K for GJ 251 b, 469.6+/-2.6K for HD 238090 b, and 370.1+/-6.8K for Lalande 21185 b. For the latter we resolve the daily aliases that were present in the SOPHIE data and that hindered an unambiguous determination of the orbital period. We find no significant signals in any of our spectral activity indicators at the planetary periods. The RV observations were accompanied by contemporaneous photometric observations. We derive stellar rotation periods of 122.1+/-2.2d and 96.7+/-3.7d for GJ 251 and HD 238090, respectively. The RV data of all three stars exhibit significant signals at the rotational period or its first harmonic. For GJ 251 and Lalande 21185, we also find long-period signals around 600d, and 2900d, respectively, which we tentatively attribute to long-term magnetic cycles. We apply a Bayesian approach to carefully model the Keplerian signals simultaneously with the stellar activity using Gaussian process regression models and extensively search for additional significant planetary signals hidden behind the stellar activity. Current planet formation theories suggest that the three systems represent a common architecture, consistent with formation following the core accretion paradigm.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/869/82
- Title:
- Carnegie-Chicago Hubble Program: RR Lyrae NIR obs.
- Short Name:
- J/ApJ/869/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry of 30 Galactic RR Lyrae variables taken with HST WFC3/IR for the Carnegie-Chicago Hubble Program. These measurements form the base of the distance-ladder measurements that comprise a pure Population II base to a measurement of Ho at an accuracy of 3%. These data are taken with the same instrument and filter (F160W) as our observations of RR Lyrae stars in external galaxies so as to minimize sources of systematic error in our calibration of the extragalactic distance scale. We calculate mean magnitudes based on one to three measurements for each RR Lyrae star using star-by-star templates generated from densely time-sampled data at optical and midinfrared wavelengths. We use four RR Lyrae stars from our sample with well-measured HST parallaxes to determine a zero-point. This zero-point will soon be improved with the large number of precise parallaxes to be provided by Gaia. We also provide preliminary calibration with the TGAS and Gaia DR2 data, and all three zero points are in agreement, to within their uncertainties.
- ID:
- ivo://CDS.VizieR/J/ApJ/862/100
- Title:
- Carnegie-Irvine Galaxy Survey VII. S0 galaxies
- Short Name:
- J/ApJ/862/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using high-quality optical images from the Carnegie-Irvine Galaxy Survey, we perform multicomponent decompositions of S0 galaxies (S0s) to derive accurate structural parameters to constrain their physical origin. Many S0s do not host prominent bulges. S0s have a broad distribution of bulge-to-total ratios (B/T) and Sersic indices (n), with average values of B/T=0.34+/-0.15 and n=2.62+/-1.02, qualitatively consistent with the notion that S0s define a parallel sequence with and may have evolved from spiral galaxies. This is further reinforced by the incidence of bars and lenses in S0s, which, when compared with the statistics in spirals, supports the idea that lenses are demised bars. However, despite their wide range of prominence, the bulges of S0s form a surprisingly uniform sequence on both the Kormendy and fundamental plane relations. There is no evidence for population dichotomy or other indications of differentiation into classical and pseudo bulges. Most of the S0s reside in the field and in groups; cluster environment is not a necessary condition for S0 production. The properties of S0 bulges show little correlation with environmental indicators, after the dependence of galaxy stellar mass on environment is taken into account. As the bulges of late-type spirals and S0s are intrinsically different, and environmental effects that may account for such evolution appear to be minimal, we conclude that late- type spirals are not plausible progenitors of S0s. The bulges of S0s likely formed at an early epoch, after which secular processes contributed little to their subsequent evolution.
- ID:
- ivo://CDS.VizieR/J/AJ/139/519
- Title:
- Carnegie supernova project. SNe Ia
- Short Name:
- J/AJ/139/519
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Carnegie Supernova Project (CSP) is a five-year survey being carried out at the Las Campanas Observatory to obtain high-quality light curves of ~100 low-redshift Type Ia supernovae (SNe Ia) in a well-defined photometric system. Here we present the first release of photometric data that contains the optical light curves of 35 SNe Ia, and near-infrared light curves for a subset of 25 events. The data comprise 5559 optical (ugriBV) and 1043 near-infrared (Y JHKs) data points in the natural system of the Swope telescope. Twenty-eight SNe have pre-maximum data, and for 15 of these, the observations begin at least 5 days before B maximum. This is one of the most accurate data sets of low-redshift SNe Ia published to date. When completed, the CSP data set will constitute a fundamental reference for precise determinations of cosmological parameters, and serve as a rich resource for comparison with models of SNe Ia.
- ID:
- ivo://CDS.VizieR/J/A+A/577/A120
- Title:
- Carrier fit analysis of LQ Hya photometry
- Short Name:
- J/A+A/577/A120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study LQ Hya photometry for 1982-2014 with the carrier fit (CF) method. As a result global continuous model for the light curve is built.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A150
- Title:
- CasA, CygA, TauA, VirA 30MHz & 77MHz models
- Short Name:
- J/A+A/635/A150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The four persistent radio sources in the northern sky with the highest flux density at metre wavelengths are Cassiopeia A, Cygnus A, Taurus A, and Virgo A; collectively they are called the A-team. Their flux densities at ultra-low frequencies (<100MHz) can reach several thousands of janskys, and they often contaminate observations of the low-frequency sky by interfering with image processing. Furthermore, these sources are foreground objects for all-sky observations hampering the study of faint signals, such as the cosmological 21cm line from the epoch of reionisation. We aim to produce robust models for the surface brightness emission as a function of frequency for the A-team sources at ultra-low frequencies. These models are needed for the calibration and imaging of wide-area surveys of the sky with low-frequency interferometers. This requires obtaining images at an angular resolution better than 1500 with a high dynamic range and good image fidelity. We observed the A-team with the Low Frequency Array (LOFAR) at frequencies between 30MHz and 77MHz using the Low Band Antenna (LBA) system. We reduced the datasets and obtained an image for each A-team source. The paper presents the best models to date for the sources Cassiopeia A, Cygnus A, Taurus A, and Virgo A between 30MHz and 77MHz. We were able to obtain the aimed resolution and dynamic range in all cases. Owing to its compactness and complexity, observations with the long baselines of the International LOFAR Telescope will be required to improve the source model for Cygnus A further.
- ID:
- ivo://CDS.VizieR/J/ApJ/613/343
- Title:
- Cas A knot and filament proper motions
- Short Name:
- J/ApJ/613/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution X-ray proper-motion measurements of Cassiopeia A using Chandra X-Ray Observatory observations from 2000 and 2002. We separate the emission into four spectrally distinct classes: Si-dominated, Fe-dominated, low-energy-enhanced, and continuum-dominated. These classes also represent distinct spatial and kinematic components.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A110
- Title:
- Cas A LOFAR and VLA images
- Short Name:
- J/A+A/612/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cassiopeia A is one of the best-studied supernova remnants. Its bright radio and X-ray emission is due to shocked ejecta. Cas A is rather unique in that the unshocked ejecta can also be studied: through emission in the infrared, the radio-active decay of ^44^Ti, and the low-frequency free-free absorption caused by cold ionised gas, which is the topic of this paper. Free-free absorption processes are acted by the mass, geometry, temperature, and ionisation conditions in the absorbing gas. Observations at the lowest radio frequencies can constrain a combination of these properties. We used Low Frequency Array (LOFAR) Low Band Antenna observations at 30-77MHz and Very Large Array (VLA) L-band observations at 1-2GHz to fit for internal absorption as parametrised by the emission measure. We simultaneously fit multiple UV-matched images with a common resolution of 17" (this corresponds to 0.25pc for a source at the distance of Cas A). The ample frequency coverage allows us separate the relative contributions from the absorbing gas, the unabsorbed front of the shell, and the absorbed back of the shell to the emission spectrum. We explored the effects that a temperature lower than the ~100-500K proposed from infrared observations and a high degree of clumping can have on the derived physical properties of the unshocked material, such as its mass and density. We also compiled integrated radio flux density measurements, fit for the absorption processes that occur in the radio band, and considered their ect on the secular decline of the source. We find a mass in the unshocked ejecta of M=2.95+/-0.48M_{sun}_ for an assumed gas temperature of T=100K. This estimate is reduced for colder gas temperatures and, most significantly, if the ejecta are clumped.We measure the reverse shock to have a radius of 114+/-6" and be centred at 23:23:26, +58:48:54 (J2000).We also find that a decrease in the amount of mass in the unshocked ejecta (as more and more material meets the reverse shock and heats up) cannot account for the observed low-frequency behaviour of the secular decline rate. To reconcile our low-frequency absorption measurements with models that reproduce much of the observed behaviour in Cas A and predict little mass in the unshocked ejecta, the ejecta need to be very clumped or the temperature in the cold gas needs to be low (~10K). Both of these options are plausible and can together contribute to the high absorption value that we find.
- ID:
- ivo://CDS.VizieR/J/ApJ/456/234
- Title:
- Cas A radio knots spectral indices
- Short Name:
- J/ApJ/456/234
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined the synchrotron spectral indices of 304 compact radio knots in the supernova remnant Cassiopeia A. A comparison of these data with the dynamical and brightness properties of these knots tabulated by Anderson & Rudnick (Cat. <J/ApJ/441/307>) indicates that spectral index shows a significant correlation with projected radius from the center of the remnant. Spectrally flat knots reside in a shell coincident with the bright radio ring, while steeper knots occupy a shell coincident with the diffuse radio plateau surrounding the ring. To a lesser extent, we find spectral index to be correlated also with the radio brightness of the knot, in the sense that brighter knots tend to have steeper spectra. No significant correlation is found between spectral index and knot deceleration or rate of brightness change. As the synchrotron spectral index traces the distribution of energy among relativistic particle populations, we use these results to study the nature of particle acceleration mechanisms active in Cas A. Given the dual shell nature of the spectral index distribution in Cas A and the lack of strong correlation between spectral index and dynamical properties of the knots, we conclude that radio-bright compact features are not sites of currently active particle acceleration in Cas A. This conclusion is in agreement with models of supersonic gaseous bullets constructed by Jones, Kang, & Tregillis (1994ApJ...432..194J). In these models, the marked synchrotron brightening which accompanies bullet deceleration is due primarily to preexisting relativistic particles radiating in rapidly amplifying shear-layer magnetic fields, rather than a large infusion of new relativistic particles accelerated in situ. Spectral variations between compact features in Cas A are more likely to reflect modulations in the background particle energy spectra within the remnant, perhaps instilled by temperature variations in the underlying thermal material. This interpretation requires that the diffuse synchrotron emission show the same spectral variations as seen in compact features; preliminary indications suggest that this is the case.
- ID:
- ivo://CDS.VizieR/J/A+A/657/A87
- Title:
- CASCADES I. Sample definition and first results
- Short Name:
- J/A+A/657/A87
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Following the first discovery of a planet orbiting a giant star in 2002, we started the CORALIE radial-velocity search for companions around evolved stars (CASCADES). We present the observations of three stars conducted at the 1.2m Leonard Euler Swiss telescope at La Silla Observatory, Chile, using the CORALIE spectrograph. We aim to detect planetary companions to intermediate-mass G- and K- type evolved stars and perform a statistical analysis of this population. We searched for new planetary systems around the stars HD22532 (TIC200851704), HD64121 (TIC264770836), and HD69123 (TIC146264536). We have followed a volume-limited sample of 641 red giants since 2006 to obtain high-precision radial-velocity measurements. We used the Data & Analysis Center for Exoplanets (DACE) platform to perform a radial-velocity analysis to search for periodic signals in the line profile and activity indices, to distinguish between planetary-induced radial-velocity variations and stellar photospheric jitter, and to search for significant signals in the radial-velocity time series to fit a corresponding Keplerian model. In this paper, we present the survey in detail, and we report on the discovery of the first three planets of the sample around the giant stars HD22532, HD64121, and HD69123.
