- ID:
- ivo://CDS.VizieR/J/A+A/621/A110
- Title:
- Two new giant planets around metal-poor stars
- Short Name:
- J/A+A/621/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Statistical studies of exoplanets have shown that giant planets are more commonly hosted by metal-rich dwarf stars than low-metallicity stars, while no such correlation is evident for lower mass planets. The search for giant planets around metal-poor stars and the estimate of their occurrence f_p_ is an important element in providing support to models of planet formation. We present results from the HARPS-N search for giant planets orbiting metal-poor (-1.0<=[Fe/H]<=-0.5dex) stars in the northern hemisphere, complementing a previous HARPS survey on southern stars in order to update the estimate of f_p_. High-precision HARPS-N observations of 42 metal-poor stars were used to search for planetary signals to be fitted using differential evolution Markov chain Monte Carlo single-Keplerian models. We then joined our detections to the results of the previous HARPS survey on 88 metal-poor stars to provide a preliminary estimate of the two-hemisphere f_p_. We report the detection of two new giant planets around HD 220197 and HD 233832. The first companion has Msini=0.20_-0.04_^+0.07^MJup and an orbital period of 1728_-80_^+162^days, and for the second companion, we find two solutions of equal statistical weight with periods of 2058_-40_^+47^ and 4047_-117_^+91^days and minimum masses of 1.78_-0.06_^+0.08^ and 2.72_-0.23_^+0.23^MJup, respectively. Joining our two detections with the three from the southern survey, we obtain a preliminary and conservative estimate of the global frequency of f_p_=3.84_-1.06_^+2.45^% for giant planets around metal-poor stars. The two new giant planets orbit dwarf stars at the metal-rich end of the HARPS-N metal-poor sample. This corroborates previous results that suggested that giant planet frequency is still a rising function of the host star [Fe/H]. We also note that all detections in the overall sample are giant long-period planets.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/159/105
- Title:
- Two new stellar associations in vicinity of the Sun
- Short Name:
- J/AJ/159/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work we report the discovery of two new stellar associations in close vicinity of the Sun at roughly 180 and 150pc. These two associations, u-Tau assoc and e-Tau assoc, were detected based on their clustering in a multi-dimensional parameter space including {alpha}, {delta}, {mu}_{alpha}_, {mu}_{delta}_, and \bar{omega} of Gaia. The fitting of pre-main-sequence model isochrones in their color-magnitude diagrams suggests that the two associations are of about 50Myr old and the group members lower than ~0.8M_{sun}_ are at the stage of post-T Tauri.
- ID:
- ivo://CDS.VizieR/J/ApJ/727/125
- Title:
- Two secondary eclipses of WASP-12b with Spitzer
- Short Name:
- J/ApJ/727/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed two secondary eclipses of the exoplanet WASP-12b using the Infrared Array Camera on the Spitzer Space Telescope. The close proximity of WASP-12b to its G-type star results in extreme tidal forces capable of inducing apsidal precession with a period as short as a few decades. This precession would be measurable if the orbit had a significant eccentricity, leading to an estimate of the tidal Love number and an assessment of the degree of central concentration in the planetary interior. An initial ground-based secondary-eclipse phase reported by Lopez-Morales et al. (0.510+/-0.002; 2010ApJ...716L..36L) implied eccentricity at the 4.5{sigma} level. The spectroscopic orbit of Hebb et al. (2009ApJ...693.1920H) has eccentricity 0.049+/-0.015, a 3{sigma} result, implying an eclipse phase of 0.509+/-0.007. However, there is a well-documented tendency of spectroscopic data to overestimate small eccentricities. Our eclipse phases are 0.5010+/-0.0006 (3.6 and 5.8um) and 0.5006+/-0.0007 (4.5 and 8.0um). An unlikely orbital precession scenario invoking an alignment of the orbit during the Spitzer observations could have explained this apparent discrepancy, but the final eclipse phase of Lopez-Morales et al. (0.510^+0.007^_-0.006_) is consistent with a circular orbit at better than 2{sigma}. An orbit fit to all the available transit, eclipse, and radial-velocity data indicates precession at <1{sigma}; a non-precessing solution fits better. We also comment on analysis and reporting for Spitzer exoplanet data in light of recent re-analyses.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A43
- Title:
- Two super-Earths orbiting TOI-402
- Short Name:
- J/A+A/627/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) is revolutionising the search for planets orbiting bright and nearby stars. In sectors 3 and 4, TESS observed TOI-402 (TIC-120896927), a bright V=9.1 K1 dwarf also known as HD15337, and found two transiting signals with periods of 4.76 and 17.18 days and radii of 1.90 and 2.21R_{Earth}_, respectively. This star was observed prior to the TESS detection as part of the radial-velocity (RV) search for planets using the HARPS spectrometer, and 85 precise RV measurements were obtained before the launch of TESS over a period of 14 years. In this paper, we analyse the HARPS RV measurements in hand to confirm the planetary nature of these two signals. HD15337 happens to present a stellar activity level similar to the Sun, with a magnetic cycle of similar amplitude and RV measurements that are affected by stellar activity. By modelling this stellar activity in the HARPS radial velocities using a linear dependence with the calcium activity index log(R'_HK_), we are able, with a periodogram approach, to confirm the periods and the planetary nature of TOI-402.01 and TOI-402.02. We then derive robust estimates from the HARPS RVs for the orbital parameters of these two planets by modelling stellar activity with a Gaussian process and using the marginalised posterior probability density functions obtained from our analysis of TESS photometry for the orbital period and time of transit. By modelling TESS photometry and the stellar host characteristics, we find that TOI-402.01 and TOI-402.02 have periods of 4.75642+/-0.00021 and 17.1784+/-0.0016 days and radii of 1.70+/-0.06 and 2.52+/-0.11 (precision 3.6 and 4.2%), respectively. By analysing the HARPS RV measurements, we find that those planets are both super-Earths with masses of 7.20+/-0.81 and 8.79+/-1.68 (precision 11.3 and 19.1%), and small eccentricities compatible with zero at 2{sigma}. Although having rather similar masses, the radii of these two planets are very different, putting them on different sides of the radius gap. By studying the temporal evolution under X-ray and UV (XUV) driven atmospheric escape of the TOI-402 planetary system, we confirm, under the given assumptions, that photo-evaporation is a plausible explanation for this radius difference. Those two planets, being in the same system and therefore being in the same irradiation environment are therefore extremely useful for comparative exoplanetology across the evaporation valley and thus bring constraints on the mechanisms responsible for the radius gap.
- ID:
- ivo://CDS.VizieR/J/AJ/137/3826
- Title:
- Two transits of the giant planet WASP-4b
- Short Name:
- J/AJ/137/3826
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry of two transits of the giant planet WASP-4b with a photometric precision of 400-800 parts per million and a time sampling of 25-40s. The two midtransit times are determined to within 6s. Together with previously published times, the data are consistent with a constant orbital period, giving no compelling evidence for period variations that would be produced by a satellite or additional planets. Analysis of the new photometry, in combination with stellar-evolutionary modeling, gives a planetary mass and radius of 1.237+/-0.064M_Jup_ and 1.365+/-0.021R_Jup_, respectively. The planet is 15% larger than expected based on previously published models of solar-composition giant planets. With data of the quality presented here, the detection of transits of a "super-Earth" of radius 1.75R_{earth}_ would have been possible.
22556. TX Psc ALMA CO(2-1) images
- ID:
- ivo://CDS.VizieR/J/A+A/621/A50
- Title:
- TX Psc ALMA CO(2-1) images
- Short Name:
- J/A+A/621/A50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed the carbon-rich asymptotic giant branch (AGB) star TX Piscium (TX Psc) with ALMA in CO(2-1) emission to investigate the circumstellar envelope (CSE) and mass-loss history of this object. Previous observations with Herschel in the far infrared have shown a ring-like structure in dust emission (2011A&A...532A.135J). Our molecular gas observations of the CO(2-1) emission line cover this structure with significantly higher spatial resolution to investigate its origin.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A112
- Title:
- TXS 2013+370 gamma-ray emitting region
- Short Name:
- J/A+A/634/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The gamma-ray production mechanism and its localization in blazars are still a matter of debate. The main goal of this paper is to constrain the location of the high-energy emission in the blazar TXS 2013+370 and to study the physical and geometrical properties of the inner jet region on sub-pc scales. TXS 2013+370 was monitored during 2002-2013 with VLBI at 15, 22, 43, and 86GHz, which allowed us to image the jet base with an angular resolution of >=0.4pc. By employing CLEAN imaging and Gaussian model-fitting, we performed a thorough kinematic analysis at multiple frequencies, which provided estimates of the jet speed, orientation, and component ejection times. Additionally, we studied the jet expansion profile and used the information on the jet geometry to estimate the location of the jet apex. VLBI data were combined with single-dish measurements to search for correlated activity between the radio, mm, and gamma-ray emission. For this purpose, we employed a cross-correlation analysis, supported by several significance tests. The high-resolution VLBI imaging revealed the existence of a spatially bent jet, described by co-existing moving emission features and stationary features. New jet features, labeled as A1, N, and N1, are observed to emerge from the core, accompanied by flaring activity in radio/mm- bands and rays. The analysis of the transverse jet width profile constrains the location of the mm core to lie <=2pc downstream of the jet apex, and also reveals the existence of a transition from parabolic to conical jet expansion at a distance of ~54pc from the core, corresponding to ~1.5x10^6^ Schwarzschild radii. The cross-correlation analysis of the broad-band variability reveals a strong correlation between the radio-mm and gamma-ray data, with the 1mm emission lagging 49 days behind the rays. Based on this, we infer that the high energy emission is produced at a distance of the order of ~1pc from the VLBI core, suggesting that the seed photon fields for the external Compton mechanism originate either in the dusty torus or in the broad-line region.
- ID:
- ivo://CDS.VizieR/J/ApJ/753/156
- Title:
- T/Y brown dwarfs with WISE photometry
- Short Name:
- J/ApJ/753/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of another seven Y dwarfs from the Wide-field Infrared Survey Explorer (WISE). Using these objects, as well as the first six WISE Y dwarf discoveries from Cushing et al. (2011ApJ...743...50C), we further explore the transition between spectral types T and Y. We find that the T/Y boundary roughly coincides with the spot where the J-H colors of brown dwarfs, as predicted by models, turn back to the red. Moreover, we use preliminary trigonometric parallax measurements to show that the T/Y boundary may also correspond to the point at which the absolute H (1.6{mu}m) and W2 (4.6{mu}m) magnitudes plummet. We use these discoveries and their preliminary distances to place them in the larger context of the solar neighborhood. We present a table that updates the entire stellar and substellar constituency within 8pc of the Sun, and we show that the current census has hydrogen-burning stars outnumbering brown dwarfs by roughly a factor of six. This factor will decrease with time as more brown dwarfs are identified within this volume, but unless there is a vast reservoir of cold brown dwarfs invisible to WISE, the final space density of brown dwarfs is still expected to fall well below that of stars. We also use these new Y dwarf discoveries, along with newly discovered T dwarfs from WISE, to investigate the field substellar mass function. We find that the overall space density of late-T and early-Y dwarfs matches that from simulations describing the mass function as a power law with slope -0.5<{alpha}<0.0; however, a power law may provide a poor fit to the observed object counts as a function of spectral type because there are tantalizing hints that the number of brown dwarfs continues to rise from late-T to early-Y. More detailed monitoring and characterization of these Y dwarfs, along with dedicated searches aimed at identifying more examples, are certainly required.
- ID:
- ivo://CDS.VizieR/J/A+A/515/A81
- Title:
- TYC 2627-638-1 BV(RI)c differential photometry
- Short Name:
- J/A+A/515/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present BV(RI)c and JHKs photometry and low- and high-resolution spectroscopy of the 11th mag G-type star TYC 2627-638-1. Our investigation reveals that the target is separated into two young, early-G-type main-sequence (or late pre-main-sequence) stars, which are most probably bound and form a wide binary system. A substellar body orbits the brighter component as implied by radial velocity variations. The brighter component possibly also has a faint, later type stellar companion. Both components of the wide binary have clear emission cores in the CaII H&K lines and filled-in Halpha absorption, indicating that both stars are chromospherically active. Our photometric time series reveals clear but only a few hundredths of a magnitude amplitude rotational modulation, which is most likely due to cool starspots. Two distinct periods, near 3.5 and 3.7-days, are found in the brightness variations. Photometry obtained separately of the two components of the wide binary show that these periodicities belong to the brighter star. The fainter component shows a much slower light variation of about 0.3mag. amplitude. In addition, long-term changes in the brightness of both stars are seen. The spectral energy distribution shows a strong near-infrared excess in the fainter component of the wide binary.
- ID:
- ivo://nasa.heasarc/tycho2
- Title:
- Tycho-2 Catalog of the 2.5 Million Brightest Stars
- Short Name:
- Tycho-2
- Date:
- 09 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Hipparcos and Tycho catalogs are the primary products of the European Space Agency's astrometric mission, Hipparcos. The satellite, which operated for four years, returned high quality scientific data from November 1989 to March 1993. The Tycho-2 catalog is an astrometric reference catalog containing positions and proper motions as well as two-color photometric data for the 2.5 million brightest stars in the sky. The Tycho-2 positions and magnitudes are based on precisely the same observations as the original Tycho catalog (hereafter Tycho-1; see <a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/239">CDS Cat. I/239</a>) collected by the star mapper of the ESA Hipparcos satellite, but Tycho-2 is much bigger and slightly more precise, owing to a more advanced reduction technique. Components of double stars with separations down to 0.8 arcsec are included. Proper motions precise to about 2.5 mas/yr are given as derived from a comparison with the Astrographic Catalogue and 143 other ground-based astrometric catalogs, all reduced to the Hipparcos celestial coordinate system. Tycho-2 supersedes in most applications Tycho-1, as well as the ACT (<a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/246">CDS Cat. I/246</a>) and the TRC (CDS Cat. I/250) catalogs based on Tycho-1. Supplement-1 (not part of this HEASARC database but available at <a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/259/suppl_1.dat.gz">https://cdsarc.cds.unistra.fr/ftp/cats/I/259/suppl_1.dat.gz</a>) lists stars from the Hipparcos and Tycho-1 catalogs which are not in Tycho-2. Supplement-2 (not part of this HEASARC database but available at <a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/259/suppl_2.dat.gz">https://cdsarc.cds.unistra.fr/ftp/cats/I/259/suppl_2.dat.gz</a>) lists 1146 Tycho-1 stars which are probably either false or heavily disturbed. The principal characteristics of the Tycho-2 catalog are summarized below. By means of proper motions the positions are transferred to the year 2000.0, the epoch of the catalog. The median values of internal standard errors are given: <pre> Mean satellite observation epoch ~J1991.5 Epoch of the Tycho-2 catalog J2000.0 Reference system ICRS coincidence with ICRS (1) +/-0.6 mas deviation from inertial (1) +/-0.25 mas/yr Number of entries 2,539,913 Astrometric standard errors (2) V_T < 9 mag 7 mas all stars, positions 60 mas all stars, proper motions 2.5 mas/yr Photometric std. errors (3) on V_T V_T < 9 mag 0.013 mag all stars 0.10 mag Star density b= 0 deg 150 stars/sq.deg. b= +/-30 deg 50 stars/sq.deg. b= +/-90 deg 25 stars/sq.deg. Completeness to 90 per cent V ~ 11.5 mag Completeness to 99 per cent V ~ 11.0 mag Number of Tycho observations ~300 10<sup>6</sup> Note (1): about all 3 axes Note (2): ratio of external to internal standard errors is ~1.0 for positions and for proper motions. Systematic errors are less than 1 mas and 0.5 mas/yr Note (3): ratio of photometric external to internal standard errors at V_T > 9 mag is below 1.5 </pre> For more information on the original catalog, please consult the Tycho-2 home page at <a href="http://www.astro.ku.dk/~erik/Tycho-2">http://www.astro.ku.dk/~erik/Tycho-2</a> For more information on the HEASARC implementation of the Tycho-2 catalog, please consult <a href="#heasarc_implementation">the "HEASARC Implementation" section</a> of this help. This database table was created at the HEASARC in June 2000 based on the ADC/<a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/259">CDS Catalog I/259</a>, using the file tyc2.dat. Galactic coordinates (calculated by converting the observed ICRS Equatorial positions) were added to this HEASARC database table in August 2005. This is a service provided by NASA HEASARC .
