- ID:
- ivo://CDS.VizieR/J/AJ/161/82
- Title:
- Photometric & spectroscopic obs. of TOI-954 and K2-329
- Short Name:
- J/AJ/161/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of two short-period Saturn-mass planets, one transiting the G subgiant TOI-954 (TIC44792534, V=10.343, T=9.78) observed in TESS sectors 4 and 5 and one transiting the G dwarf K2-329 (EPIC246193072, V=12.70, K=10.67) observed in K2 campaigns 12 and 19. We confirm and characterize these two planets with a variety of ground-based archival and follow-up observations, including photometry, reconnaissance spectroscopy, precise radial velocity, and high-resolution imaging. Combining all available data, we find that TOI-954b has a radius of 0.852_-0.062_^+0.053^R_Jup_ and a mass of 0.174_-0.017_^+0.018^M_Jup_ and is in a 3.68day orbit, while K2-329b has a radius of 0.774_-0.024_^+0.026^R_Jup_ and a mass of 0.260_-0.022_^+0.020^M_Jup_ and is in a 12.46day orbit. As TOI-954b is 30 times more irradiated than K2-329b but more or less the same size, these two planets provide an opportunity to test whether irradiation leads to inflation of Saturn-mass planets and contribute to future comparative studies that explore Saturn-mass planets at contrasting points in their lifetimes.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/442/3044
- Title:
- Photometry and abundances of NGC1851 stars
- Short Name:
- J/MNRAS/442/3044
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 1851 is surrounded by a stellar component that extends more than 10 times beyond the tidal radius. Although the nature of this stellar structure is not known, it has been suggested to be a sparse halo of stars or associated with a stellar stream. We analyse the nature of this intriguing stellar component surrounding NGC 1851 by investigating its radial velocities and chemical composition, in particular in comparison with those of the central cluster analysed in a homogeneous manner. In total we observed 23 stars in the halo with radial velocities consistent with NGC 1851, and for 15 of them we infer [Fe/H] abundances. Our results show that (i) stars dynamically linked to NGC 1851 are present at least up to ~2.5 tidal radii, supporting the presence of a halo of stars surrounding the cluster; (ii) apart from the NGC 1851 radial velocity-like stars, our observed velocity distribution agrees with that expected from Galactic models, suggesting that no other substructure (such as a stream) at different radial velocities is present in our field; (iii) the chemical abundances for the s-process elements Sr and Ba are consistent with the s-normal stars observed in NGC 1851; (iv) all halo stars have metallicities, and abundances for the other studied elements Ca, Mg and Cr, consistent with those exhibited by the cluster. The complexity of the whole NGC 1851 cluster+halo system may agree with the scenario of a tidally disrupted dwarf galaxy in which NGC 1851 was originally embedded.
- ID:
- ivo://CDS.VizieR/J/A+A/399/543
- Title:
- Photometry and Coravel observations of IC 2488
- Short Name:
- J/A+A/399/543
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new UBV photoelectric observations of 119 stars in the field of the southern open cluster IC 2488, supplemented by DDO and Washington photometry and Coravel radial velocities for a sample of red giant candidates. Nearly 50% of the stars sampled - including three red giants and one blue straggler - are found to be probable cluster members. Photometric membership probabilities of the red giant candidates show good agreement with those obtained from Coravel data. A mean radial velocity of -2.63+/-0.06km/s is derived for the cluster giants. The reddening across the cluster is found to be uniform, the mean value being E(B-V)=0.24+/-0.04. IC 2488, located at a distance of (1250+/-120) pc from the Sun and 96 pc below the Galactic plane, is most probably not related to the planetary nebula ESO 166-PN21. A metal abundance [Fe/H]=0.10+/-0.06 relative to the Sun is determined from DDO data of the red giant members, in good agreement with the [Fe/H] values derived from five independent Washington abundance indices. An age of 180Myr is determined from the fitting of isochrones computed with convective overshooting for Z=0.019. The isochrone for logt=8.25 reproduces remarkably well not only the morphology of the upper main sequence but also the observed red giant pattern.
- ID:
- ivo://CDS.VizieR/J/PASP/106/281
- Title:
- Photometry and radial velocities in NGC752
- Short Name:
- J/PASP/106/281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using all available proper-motion and radial-velocity data, including new radial-velocity observations obtained for this investigation, probable members of the open cluster NGC 752 have been identified. Photoelectric data on six systems have been transformed and collated to form an internally consistent sample on the BV system. Binaries have been identified using photometric and radial-velocity data, including a photographic survey for variability and the radial-velocity observations of this study. Analysis of the data leads to the following cluster parameters and their probable errors: E(B-V) = 0.035+/-0.005mag, Fe/H = -0.15+/-0.05dex, and (m-M) = 8.25+/-0.10mag. The spread in color among stars in the color-magnitude diagram (CMD) along the main sequence from the turnoff to the unevolved main sequence is the consequence of a rich population of binaries. Due to its age and the comprehensive data available for the cluster, NGC 752 provides an ideal test of a variety of evolutionary phenomena. Comparison with theoretical isochrones normalized in an internally consistent manner leads to the conclusion that the morphology and distribution of stars in the CMD can best be matched using models that include convective overshoot, particularly those of Schaller et al. (1992A&AS...96..269S). Despite their differences, the traditional and the overshoot isochrones both imply very similar ages, 1.9+/-0.2Gyr and 1.7+/-0.1Gyr, respectively, for the cluster.
- ID:
- ivo://CDS.VizieR/V/125
- Title:
- Photometry and Spectroscopy for Luminous Stars
- Short Name:
- V/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- of the paper: The birthrate of stars of masses >=10M_{sun}_ is estimated from a sample of just over 400 O3-B2 dwarfs within 1.5kpc of the Sun and the result extrapolated to estimate the Galactic supernova rate contributed by such stars. The solar-neighborhood Galactic-plane massive star birthrate is estimated at ~176stars/kpc^3^/Myr. On the basis of a model in which the Galactic stellar density distribution comprises a "disk+central hole" like that of the dust infrared emission (as proposed by Drimmel and Spergel), the Galactic supernova rate is estimated at probably not less than ~1 nor more than ~2 per century and the number of O3-B2 dwarfs within the solar circle at ~200000.
- ID:
- ivo://CDS.VizieR/J/A+AS/95/87
- Title:
- Photometry and Spectroscopy in A2218
- Short Name:
- J/A+AS/95/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new photometric and spectroscopic observations of objects in the field of the cluster of galaxies Abell 2218. The photometric survey, centered on the cluster core, extends to a field of about 4'x4'. It was performed in 5 bands (B, g, r, i and z filters). This sample, which includes 729 objects, is about three times larger than the survey made by Butcher and collaborator (Butcher et al., 1983ApJS...52..183B, Butcher & Oemler, 1984ApJ...285..426B) in the same central region of the field. Only 228 objects appear in both catalogues since our survey covers a smaller region.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/1484
- Title:
- Photometry and spectroscopy in IC 2391
- Short Name:
- J/ApJ/706/1484
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the stellar and substellar mass function (MF) of the open cluster IC 2391, plus its radial dependence, and use this to put constraints on the formation mechanism of brown dwarfs (BDs). Our multi-band optical and infrared photometric survey with spectroscopic follow-up covers 11deg^2^, making it the largest survey of this cluster to date. From our preliminary spectroscopic follow-up, to confirm BD status and cluster membership, we find that all candidates are M dwarfs (in either the field or the cluster), demonstrating the efficiency of our photometric selection method in avoiding contaminants (e.g., red giants). About half of our photometric candidates for which we have spectra are spectroscopically confirmed as cluster members; two are new spectroscopically confirmed BD members of IC 2391.
- ID:
- ivo://CDS.VizieR/J/AJ/150/33
- Title:
- Photometry and spectroscopy of HATS-9 and HATS-10
- Short Name:
- J/AJ/150/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of two transiting extrasolar planets by the HATSouth survey. HATS-9b orbits an old (10.8+/-1.5Gyr) V=13.3 G dwarf star with a period p~~1.9153days. The host star has a mass of 1.03M_{sun}_, radius of 1.503R_{sun}_, and effective temperature 5366+/-70K. The planetary companion has a mass of 0.837M_J_ and radius of 1.065R_J_, yielding a mean density of 0.85g/cm^-3^. HATS-10b orbits a V=13.1 G dwarf star with a period p~~3.3128days. The host star has a mass of 1.1M_{sun}_, radius of 1.11R_{sun}_, and effective temperature 5880+/-120K. The planetary companion has a mass of 0.53M_J_ and radius of 0.97R_J_, yielding a mean density of 0.7g/cm3. Both planets are compact in comparison with planets receiving similar irradiation from their host stars and lie in the nominal coordinates of Field 7 of K2, but only HATS-9b falls on working silicon. Future characterization of HATS-9b with the exquisite photometric precision of the Kepler telescope may provide measurements of its reflected light signature.
- ID:
- ivo://CDS.VizieR/J/AJ/153/215
- Title:
- Photometry and spectroscopy of KELT-11
- Short Name:
- J/AJ/153/215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a transiting exoplanet, KELT-11b, orbiting the bright (V=8.0) subgiant HD93396. A global analysis of the system shows that the host star is an evolved subgiant star with T_eff_=5370+/-51K, M_*_=1.438_-0.052_^+0.061^M_{Sun}_, R_*_=2.72_-0.17_^+0.21^R_{Sun}_, logg_*_=3.727_-0.046_^+0.040^, and [Fe/H]=0.180+/-0.075. The planet is a low-mass gas giant in a P=4.736529+/-0.00006 day orbit, with M_P_=0.195+/-0.018M_J_, R_P_=1.37_-0.12_^+0.15^R_J_, {rho}_P_=0.093_-0.024_^+0.028^g/cm^3^, surface gravity logg_P_=2.407_-0.086_^+0.080^, and equilibrium temperature T_eq_=1712_-46_^+51^K. KELT-11 is the brightest known transiting exoplanet host in the southern hemisphere by more than a magnitude and is the sixth brightest transit host to date. The planet is one of the most inflated planets known, with an exceptionally large atmospheric scale height (2763km), and an associated size of the expected atmospheric transmission signal of 5.6%. These attributes make the KELT-11 system a valuable target for follow-up and atmospheric characterization, and it promises to become one of the benchmark systems for the study of inflated exoplanets.
- ID:
- ivo://CDS.VizieR/J/AJ/147/7
- Title:
- Photometry and spectroscopy of NGC 6520
- Short Name:
- J/AJ/147/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use CCD and photoelectric photometry with Stromgren filters along with medium resolution spectra to investigate NGC 6520, an open cluster very nearly in the direction of the galactic center. We find an age of 60Myr, a distance of 2kpc, and an average reddening E(b-y)=0.295, which increases toward the south. The average heliocentric radial velocity of the B stars is -29km/s, while the velocity of the nearby Barnard 86 is about 0 (heliocentric; -11km/s compared to the LSR). This velocity difference amounts to about 1.8kpc since the cluster formed, implying that it is extremely doubtful NGC6520 is related to Barnard 86.