- ID:
- ivo://CDS.VizieR/J/A+A/515/A100
- Title:
- VI light curves of NGC 1039 solar-type stars
- Short Name:
- J/A+A/515/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Employing photometric rotation periods for solar-type stars in NGC 1039 [M 34], a young, nearby open cluster, we use its mass-dependent rotation period distribution to derive the cluster's age in a distance independent way, i.e., the so-called gyrochronology method. We present an analysis of 55 new rotation periods, using light curves derived from differential photometry, for solar type stars in the open cluster NGC 1039 [M 34]. We also exploit the results of a recently-completed, standardized, homogeneous BVIc CCD survey of the cluster, performed by the Indiana Group of the WIYN open cluster survey, in order to establish photometric cluster membership and assign B-V colours to each photometric variable. We describe a methodology for establishing the gyrochronology age for an ensemble of solar-type stars. Empirical relations between rotation period, photometric colour and stellar age (gyrochronology) are used to determine the age of M 34.
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- ID:
- ivo://CDS.VizieR/J/A+A/610/A63
- Title:
- WASP-151b, WASP-153b, WASP-156b
- Short Name:
- J/A+A/610/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of three transiting exoplanets by the SuperWASP survey and the SOPHIE spectrograph with mass and radius determined with a precision better than 15%. WASP-151b and WASP-153b are two hot Saturns with masses, radii, densities and equilibrium temperatures of 0.31^+0.04^_-0.03_M_J_, 1.13^+0.03^_-0.03_R_J_, 0.22^+0.03^_-0.02_rho_J_ and 1,290^+20^_-10_K, and 0.39^+0.02^_-0.02_M_J_, 1.55^+0.10^_-0.08_R_J_, 0.11^+0.02^_-0.02{rho}_J_ and 1,700^+40^ _-40_K, respectively. Their host stars are early G type stars (with magV ~ 13) and their orbital periods are 4.53 and 3.33 days, respectively. WASP-156b is a Super-Neptune orbiting a K type star (magV = 11.6). It has a mass of 0.128^+0.010^_-0.009_M_J_, a radius of 0.51^+0.02^_ -0.02 R_J_, a density of 1.0^+0.1^_-0.1_{rho}_J_, an equilibrium temperature of 970^+30^_-20_K and an orbital period of 3.83 days.
- ID:
- ivo://CDS.VizieR/J/ApJ/837/15
- Title:
- WISE IR excesses among main sequence stars
- Short Name:
- J/ApJ/837/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study presents a search for infrared (IR) excess in the 3.4, 4.6, 12, and 22{mu}m bands in a sample of 216 targets, composed of solar sibling, twin, and analog stars observed by the Wide-field Infrared Survey Explorer (WISE) mission. In general, an IR excess suggests the existence of warm dust around a star. We detected 12{mu}m and/or 22{mu}m excesses at the 3{sigma} level of confidence in five solar analog stars, corresponding to a frequency of 4.1% of the entire sample of solar analogs analyzed, and in one out of 29 solar sibling candidates, confirming previous studies. The estimation of the dust properties shows that the sources with IR excesses possess circumstellar material with temperatures that, within the uncertainties, are similar to that of the material found in the asteroid belt in our solar system. No photospheric flux excess was identified at the W1 (3.4{mu}m) and W2 (4.6{mu}m) WISE bands, indicating that, in the majority of stars of the present sample, no detectable dust is generated. Interestingly, among the 60 solar twin stars analyzed in this work, no WISE photospheric flux excess was detected. However, a null-detection excess does not necessarily indicate the absence of dust around a star because different causes, including dynamic processes and instrument limitations, can mask its presence.
- ID:
- ivo://CDS.VizieR/J/ApJ/855/75
- Title:
- 24 years monitoring of Sun and Sun-like stars
- Short Name:
- J/ApJ/855/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare patterns of variation for the Sun and 72 Sun-like stars by combining total and spectral solar irradiance measurements between 2003 and 2017 from the SORCE satellite, Stromgren b, y stellar photometry between 1993 and 2017 from Fairborn Observatory, and solar and stellar chromospheric CaII H+K emission observations between 1992 and 2016 from Lowell Observatory. The new data and their analysis strengthen the relationships found previously between chromospheric and brightness variability on the decadal timescale of the solar activity cycle. Both chromospheric H+K and photometric b, y variability among Sun-like stars are related to average chromospheric activity by power laws on this timescale. Young active stars become fainter as their H+K emission increases, and older, less active, more Sun-age stars tend to show a pattern of direct correlation between photometric and chromospheric emission variations. The directly correlated pattern between total solar irradiance and chromospheric Ca ii emission variations shown by the Sun appears to extend also to variations in the Stromgren b, y portion of the solar spectrum. Although the Sun does not differ strongly from its stellar age and spectral class mates in the activity and variability characteristics that we have now studied for over three decades, it may be somewhat unusual in two respects: (1) its comparatively smooth, regular activity cycle, and (2) its rather low photometric brightness variation relative to its chromospheric activity level and variation, perhaps indicating that facular emission and sunspot darkening are especially well-balanced on the Sun.
- ID:
- ivo://CDS.VizieR/J/ApJ/457/L99
- Title:
- 25yr CaII-HK observations of F-K nearby stars
- Short Name:
- J/ApJ/457/L99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We find a significant correlation between the magnetic and rotational moments for a sample of 112 lower main-sequence stars. The rotational moment is calculated from measurements of the rotation period in most of the stars (not from the projected rotational velocity inferred from Doppler broadening). The magnetic moment is computed from a database of homogeneous measurements of the mean level of Ca II H and K emission fluxes sampled for most of the stars over an interval of 25yr. The slope connecting the logarithm of the magnetic moment and the logarithm of the rotational moment is about +0.5-0.6, with a Pearson correlation coefficient of about +0.9. The scatter of points from the mean relation has a component that is natural and caused by decade-long surface variability.
