- ID:
- ivo://CDS.VizieR/J/A+A/650/A188
- Title:
- G 264-012 and Gl 393 radial velocity curves
- Short Name:
- J/A+A/650/A188
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We report the discovery of two planetary systems, namely G 264-012, an M4.0 dwarf with two terrestrial planets (M_b_sini=2.50^+0.29^_-0.30_M_{sun}_ and M_c_sini=3.75^+0.48^_-0.47_M_{sun}_), and Gl 393, a bright M2.0 dwarf with one terrestrial planet (M_b_sini=1.71+/-0.24M_{sun}_). Although both stars were proposed to belong to young stellar kinematic groups, we estimate their ages to be older than about 700Ma. The two planets around G 264-012 were discovered using only radial-velocity (RV) data from the CARMENES exoplanet survey, with estimated orbital periods of 2.30d and 8.05d, respectively. Photometric monitoring and analysis of activity indicators reveal a third signal present in the RV measurements, at about 100d, caused by stellar rotation. The planet Gl 393b was discovered in the RV data from the HARPS, CARMENES, and HIRES instruments. Its identification was only possible after modelling, with a Gaussian process (GP), the variability produced by the magnetic activity of the star. For the earliest observations, this variability produced a forest of peaks in the periodogram of the RVs at around the 34d rotation period determined from Kepler data, which disappeared in the latest epochs. After correcting for them with this GP model, a significant signal showed at a period of 7.03d. No significant signals in any of our spectral activity indicators or contemporaneous photometry were found at any of the planetary periods. Given the orbital and stellar properties, the equilibrium temperatures of the three planets are all higher than that for Earth. Current planet formation theories suggest that these two systems represent a common type of architecture. This is consistent with formation following the core accretion paradigm.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/530/A118
- Title:
- G29.96-0.02 and G35.20-1.74 1mm and 3mm maps
- Short Name:
- J/A+A/530/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Most work on high-mass star formation has focused on observations of young massive stars in protoclusters. Very little is known about the preceding stage. Here, we present a new high-resolution study of pre-protocluster regions in tracers exclusively probing the coldest and dense gas (NH_2_ D). The two target regions G29.96-0.02 and G35.20-1.74 (W48) are drawn from the SCAMPS project, which searches for pre-protoclusters near known ultracompact HII regions. We used our data to constrain the chemical, thermal, kinematic, and physical conditions (i.e., densities) in G29.96e and G35.20w. NH_3_, NH_2_ D, HCO^+^, and continuum emission were mapped using the VLA, PdBI, and BIMA.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A36
- Title:
- G346.056-0.021 and G346.077-0.056 radio images
- Short Name:
- J/A+A/612/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multiwavelength study of two southern Galactic H II regions G346.056-0.021 and G346.077-0.056 which are located at a distance of 10.9kpc. The distribution of ionized gas, cold and warm dust, and the stellar population associated with the two H II regions are studied in detail using measurements at near-infrared, mid-infrared, far-infrared, submillimeter and radio wavelengths. The radio continuum maps at 1280 and 610MHz were obtained using the Giant Metrewave Radio Telescope to probe the ionized gas. The dust temperature, column density, and dust emissivity maps were generated using modified blackbody fits in the far-infrared wavelength range 160-500um. Various near- and mid-infrared color and magnitude criteria were adopted to identify candidate ionizing star(s) and the population of young stellar objects in the associated field. The radio maps reveal the presence of diffuse ionized emission displaying distinct cometary morphologies. The 1280MHz flux densities translate to ZAMS spectral types in the range O7.5V-O7V and O8.5V-O8V for the ionizing stars of G346.056-0.021 and G346.077-0.056, respectively. A few promising candidate ionizing star(s) are identified using near-infrared photometric data. The column density map shows the presence of a large, dense dust clump enveloping G346.077-0.056. The dust temperature map shows peaks towards the two HII regions. The submillimeter image shows the presence of two additional clumps, one being associated with G346.056-0.021. The masses of the clumps are estimated to range between ~1400 and 15250M_{sun}_. Based on simple analytic calculations and the correlation seen between the ionized gas distribution and the local density structure, the observed cometary morphology in the radio maps is better explained invoking the champagne-flow model.
- ID:
- ivo://CDS.VizieR/J/A+AS/129/237
- Title:
- G and K dwarfs abundances
- Short Name:
- J/A+AS/129/237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The table presents the abundances of all 47 dwarf stars analysed in the paper. We give abundances relative to the Sun in the standard notation of [X/H]=log(X/H)_star_-log(X/H)_{sun}_. The 5 K dwarf stars and 3 stars in common with Barbuy & Grenon (1990) appear at the end of the table. The label of each column indicates the ion the quoted abundances are derived from. For each star we give the abundance, [X/H], the line-to-line scatter (if more than one line is used) and the number of lines used. The stars are ordered in the same way as in Table 1 in the paper, ie. the K dwarf stars and the stars in common with Barbuy & Grenon (1990) are found at the end.
- ID:
- ivo://CDS.VizieR/J/MNRAS/336/879
- Title:
- G and K dwarfs UBV(RI)c and ubvy photometry
- Short Name:
- J/MNRAS/336/879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- K dwarfs have lifetimes older than the present age of the Galactic disc, and are thus ideal stars for investigating the chemical evolution of the disc. We have developed several photometric metallicity indicators for K dwarfs, based on a sample of accurate spectroscopic metallicities for 34 disc and halo G and K dwarfs. The photometric metallicities lead us to develop a metallicity index for K dwarfs based only on their position in the colour-absolute-magnitude diagram. Metallicities have been determined for 431 single K dwarfs drawn from the Hipparcos catalogue, selecting the stars by absolute magnitude and removing multiple systems. The sample is essentially a complete reckoning of the metal content in nearby K dwarfs. We use stellar isochrones to mark the stars by mass, and select a subset of 220 of the stars, which is complete within a narrow mass interval. We fit the data with a model of the chemical evolution of the solar cylinder. We find that only a modest cosmic scatter is required to fit our age-metallicity relation. The model assumes two main infall episodes for the formation of the halo-thick disc and thin disc, respectively. The new data confirm that the solar neighbourhood formed on a long time-scale of the order of 7Gyr.
- ID:
- ivo://CDS.VizieR/J/A+A/574/A116
- Title:
- G and K giant stars stellar parameters
- Short Name:
- J/A+A/574/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained precise radial velocities for a sample of 373 G and K type giants at Lick Observatory regularly over more than 12 years. Planets have been identified around 15 of these giant stars, and an additional 20 giant stars host planet candidates. We are interested in the occurrence rate of substellar companions around giant stars as a function of stellar mass and metallicity. We probe the stellar mass range from approximately 1 to beyond 3M_{sun}_, which is not being explored by main-sequence samples. We fit the giant planet occurrence rate as a function of stellar mass and metallicity with a Gaussian and an exponential distribution, respectively.
- ID:
- ivo://CDS.VizieR/J/AJ/162/57
- Title:
- g- and Ks-band flux of K2-22 with LBT
- Short Name:
- J/AJ/162/57
- Date:
- 14 Mar 2022 06:59:12
- Publisher:
- CDS
- Description:
- The disintegrating planet candidate K2-22b shows periodic and stochastic transits best explained by an escaping debris cloud. However, the mechanism that creates the debris cloud is unknown. The grain size of the debris as well as its sublimation rate can be helpful in understanding the environment that disintegrates the planet. Here, we present simultaneous photometry with the g band at 0.48{mu}m and KS band at 2.1{mu}m using the Large Binocular Telescope. During an event with very low dust activity, we put a new upper limit on the size of the planet of 0.71R{Earth} or 4500km. We also detected a medium depth transit that can be used to constrain the dust particle sizes. We find that the median particle size must be larger than about 0.5-1.0{mu}m, depending on the composition of the debris. This leads to a high mass-loss rate of about 3x108kg/s, which is consistent with hydrodynamic escape models. If they are produced by some alternate mechanism such as explosive volcanism, it would require extraordinary geological activity. Combining our upper limits on the planet size with the high mass-loss rate, we find a lifetime of the planet of less than 370Myr. This drops to just 21Myr when adopting the 0.02M{Earth} mass predicted from hydrodynamical models.
- ID:
- ivo://CDS.VizieR/III/10B
- Title:
- G5 and later stars in a North Galactic Pole region
- Short Name:
- III/10B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is an objective-prism survey of late-type stars in a region of 396 square degrees surrounding the north galactic pole. The objective-prism spectra employed have a dispersion of 58 nm/mm at H-{gamma} and extend into the ultraviolet region. The catalog contains the magnitudes and spectral classes of 4027 stars of class G5 and later, complete to a limiting photographic magnitude of 13.0. The spectral classification of the stars is based on the Yerkes system. The catalog includes the serial numbers of the stars corresponding to the numbers on the identification charts in Upgren (1984), BD and HD numbers, B magnitudes, spectral classes, and letters designating the subregion and identification chart on which each star is located. This survey was undertaken to determine the space densities at varying distances from the galactic plane. Accurate separation of the surveyed stars of G5 and later into giants and dwarfs was achieved through the use of the UV region as well as conventional methods of classification. The resulting catalog of 4027 stars is probably complete over the region to a limiting photographic magnitude of 13.0. The region covered by the survey is the same as that discussed by Slettebak and Stock (1959) and is in the approximate range RA 11:30 to 13:00, Declination +25 to +50 (B1950.0). The catalog includes all M and Carbon stars previously published by Upgren (1960). For a discussion of the classification criteria, the combining of multiple classifications (each spectral image was classified twice), the determination of magnitudes, and additional details about the catalog, the source reference should be consulted. Corrections, accurate positions, more identifications, and remarks have been added in Nov. 2015 by B. Skiff in the file "positions.dat"; see the "History" section below for details.
- ID:
- ivo://CDS.VizieR/J/A+A/575/A111
- Title:
- GAPS V: Global analysis of the XO-2 system
- Short Name:
- J/A+A/575/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- XO-2 is the first confirmed wide stellar binary system where the almost twin components XO-2N and XO-2S have planets, and it is a peculiar laboratory in which to investigate the diversity of planetary systems. This stimulated a detailed characterization study of the stellar and planetary components based on new observations. We collected high-resolution spectra with the HARPS-N spectrograph and multi-band light curves. Spectral analysis led to an accurate determination of the stellar atmospheric parameters and characterization of the stellar activity, and high-precision radial velocities of XO-2N were measured. We collected 14 transit light curves of XO-2Nb used to improve the transit parameters. Photometry provided accurate magnitude differences between the stars and a measure of their rotation periods.
- ID:
- ivo://CDS.VizieR/J/A+A/462/875
- Title:
- Garching-Bonn Deep Survey (GaBoDS) IX
- Short Name:
- J/A+A/462/875
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of the present work is the construction of a mass-selected galaxy cluster sample based on weak gravitational lensing methods. This sample will be subject to spectroscopic follow-up observations. We apply the mass aperture statistics (S-statistics) and a new derivative of it (the P-statistics) to 19 square degrees of high quality, single colour wide field imaging data obtained with the WFI@MPG/ESO 2.2m telescope. For the statistics a family of filter functions is used that approximates the expected tangential radial shear profile and thus allows for the efficient detection of mass concentrations. The exact performance of the P-statistics still needs to be evaluated by means of simulations.