- ID:
- ivo://CDS.VizieR/J/AJ/161/171
- Title:
- THYME. V. Discovering a new stellar association
- Short Name:
- J/AJ/161/171
- Date:
- 08 Mar 2022
- Publisher:
- CDS
- Description:
- The detection and characterization of young planetary systems offer a direct path to study the processes that shape planet evolution. We report on the discovery of a sub-Neptune-sized planet orbiting the young star HD110082 (TOI-1098). Transit events we initially detected during TESS Cycle 1 are validated with time-series photometry from Spitzer. High-contrast imaging and high-resolution, optical spectra are also obtained to characterize the stellar host and confirm the planetary nature of the transits. The host star is a late-F dwarf (M*=1.2M{sun}) with a low-mass, M dwarf binary companion (M*=0.26M{sun}) separated by nearly one arcminute (~6200au). Based on its rapid rotation and Lithium absorption, HD110082 is young, but is not a member of any known group of young stars (despite proximity to the Octans association). To measure the age of the system, we search for coeval, phase-space neighbors and compile a sample of candidate siblings to compare with the empirical sequences of young clusters and to apply quantitative age-dating techniques. In doing so, we find that HD110082 resides in a new young stellar association we designate MELANGE-1, with an age of 250_-70_^+50^Myr. Jointly modeling the TESS and Spitzer light curves, we measure a planetary orbital period of 10.1827days and radius of Rp=3.2{+/-}0.1R{Earth}. HD110082b's radius falls in the largest 12% of field-age systems with similar host-star mass and orbital period. This finding supports previous studies indicating that young planets have larger radii than their field-age counterparts.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/495/2713
- Title:
- TIC-231005575 photometric and RV curves
- Short Name:
- J/MNRAS/495/2713
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) has produced a large number of single transit event candidates which are being monitored by the Next Generation Transit Survey (NGTS). We observed a second epoch for the TIC-231005575 system (Tmag=12.06, Teff=5500+/-85K) with NGTS and a third epoch with Las Cumbres Observatory's (LCO) telescope in South Africa to constrain the orbital period (P=61.777d). Subsequent radial velocity measurements with CORALIE revealed the transiting object has a mass of M2=0.128+/-0.003M_{sun}_, indicating the system is a G-M binary. The radius of the secondary is R2=0.154+/-0.008R_{sun}_ and is consistent with models of stellar evolution to better than 1-{sigma}.
- ID:
- ivo://CDS.VizieR/J/A+A/488/481
- Title:
- Time delays and H0 from WFI J2033-4723
- Short Name:
- J/A+A/488/481
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gravitationally lensed quasars can be used to map the mass distribution in lensing galaxies and to estimate the Hubble constant H0 by measuring the time delays between the quasar images. Here we report the measurement of two independent time delays in the quadruply imaged quasar WFI J2033-4723 (z=1.66). Our data consist of R-band images obtained with the Swiss 1.2m EULER telescope located at La Silla and with the 1.3m SMARTS telescope located at Cerro Tololo. The light curves have 218 independent epochs spanning 3 full years of monitoring between March 2004 and May 2007, with a mean temporal sampling of one observation every 4th day. We measure the time delays using three different techniques, and we obtain Dt(B-A)=35.5+/-1.4days (3.8%) and Dt(B-C)=62.6^+4.1^_-2.3_days (^+6.5%^_-3.7%_), where A is a composite of the close, merging image pair. After correcting for the time delays, we find R-band flux ratios of FA/FB=2.88+/-0.04, FA/FC=3.38+/-0.06, and FA1/FA2=1.37+/-0.05 with no evidence for microlensing variability over a time scale of three years. However, these flux ratios do not agree with those measured in the quasar emission lines, suggesting that longer term microlensing is present. Our estimate of H0 agrees with the concordance value: non-parametric modeling of the lensing galaxy predicts H0=67^+13^_-10_km/s/Mpc, while the Single Isothermal Sphere model yields H0=63^+7^_-3_km/s/Mpc (68% confidence level). More complex lens models using a composite de Vaucouleurs plus NFW galaxy mass profile show twisting of the mass isocontours in the lensing galaxy, as do the non-parametric models. As all models also require a significant external shear, this suggests that the lens is a member of the group of galaxies seen in field of view of WFI J2033-4723.
- ID:
- ivo://CDS.VizieR/J/PASP/123/26
- Title:
- Time of Maxima for the SX Phe star XX Cyg
- Short Name:
- J/PASP/123/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- XX Cyg is a High Amplitude {delta} Scuti star which has been extensively studied because of its changing period. We present 64 new times of maxima which have been combined with 174 times of maxima from literature, in order to give an updated ephemeris and O-C plot for XX Cyg. Its period, currently found to be 0.134865117(3) days, is shown to be increasing continuously, which has lead to a new calculated value of (1/P)(dP/dt)=(1.33+/-0.09)10^-8^yr^-1^
- ID:
- ivo://CDS.VizieR/J/other/JAD/15.1
- Title:
- Time-series of 9 cataclysmic variables
- Short Name:
- J/other/JAD/15.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time-series photometry of nine cataclysmic variables: EI UMa, V844 Her, V751 Cyg, V516 Cyg, GZ Cnc, TY Psc, V1315 Aql, ASAS J002511+1217.2, V1315 Aql and LN UMa. The observations were conducted at various observatories, covering 170 hours and comprising 7850 data points in total. For the majority of targets we confirm previously reported periodicities and for some of them we give, for the first time through photometry, their underlying spectroscopic orbital period. For those dwarf-nova systems which we observed during both quiescence and outburst, the increase in brightness was accompanied by a decrease in the level of flickering. For the eclipsing system V1315 Aql we have covered 9 eclipses, and obtained a refined orbital ephemeris. We find that, during its long baseline of observations, no change in the orbital period of this system has occurred. V1315 Aql also shows eclipses of variable depth.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A106
- Title:
- Time-series photometry of 2012 DA14
- Short Name:
- J/A+A/559/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The object 2012 DA14 is a near-Earth asteroid with a size of several tens of meters. It had approached closely the Earth on 15 February 2013 UT, providing an opportunity for precise measurements of this tiny asteroid. The solar phase angle of 2012 DA14 had varied widely around its closest approach but was almost constant during the following night. We performed time-series photometric observations on those two nights to determine the rotational properties and phase effect. The observations were carried out using the 0.55-m telescope at Saitama University, Japan. The R-band images were obtained continuously over a 2h period at the closest approach and for about 5h on the next night.
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/2396
- Title:
- Time-series photometry of IC 348
- Short Name:
- J/MNRAS/462/2396
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present long-term photometric observations of the young open cluster IC 348 with a baseline time-scale of 2.4yr. Our study was conducted with several telescopes from the Young Exoplanet Transit Initiative (YETI) network in the Bessell R band to find periodic variability of young stars. We identified 87 stars in IC 348 to be periodically variable; 33 of them were unreported before. Additionally, we detected 61 periodic non-members of which 41 are new discoveries. Our wide field of view was the key to those numerous newly found variable stars. The distribution of rotation periods in IC 348 has always been of special interest. We investigate it further with our newly detected periods but we cannot find a statistically significant bimodality. We also report the detection of a close eclipsing binary in IC 348 composed of a low-mass stellar component (M>~0.09M_{sun}_) and a K0 pre-main sequence star (M~2.7M_{sun}_). Furthermore, we discovered three detached binaries among the background stars in our field of view and confirmed the period of a fourth one.
- ID:
- ivo://CDS.VizieR/J/A+A/611/A85
- Title:
- Time-series photometry of V391 Peg
- Short Name:
- J/A+A/611/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V391 Peg (alias HS 2201+2610) is a subdwarf B (sdB) pulsating star that shows both p- and g-modes. By studying the arrival times of the p-mode maxima and minima through the O-C method, the presence of a planet was inferred with an orbital period of 3.2yr and a minimum mass of 3.2M_Jup_ (Silvotti et al., 2007Natur.449..189S). In this article we present an updated O-C analysis using a larger data set of 1066 hours of photometric time series (~2.5x larger in terms of the number of data points), which covers the period between 1999 and 2012 (compared with 1999-2006 of the previous analysis). Up to the end of 2008, the new O-C diagram of the main pulsation frequency (f1) is compatible with (and improves) the previous two-component solution representing the long-term variation of the pulsation period (parabolic component) and the giant planet (sine wave component). Since 2009, the O-C trend of f1 changes, and the time derivative of the pulsation period (dP/dt) passes from positive to negative; the reason of this change of regime is not clear and could be related to nonlinear interactions between different pulsation modes. With the new data, the O-C diagram of the secondary pulsation frequency (f2) continues to show two components (parabola and sine wave), like in the previous analysis. Various solutions are proposed to fit the O-C diagrams of f1 and f2 , but in all of them, the sinusoidal components of f1 and f2 differ or at least agree less well than before. The nice agreement found previously was a coincidence due to various small effects that are carefully analysed. Now, with a larger dataset, the presence of a planet is more uncertain and would require confirmation with an independent method. The new data allow us to improve the measurement of dP/dt for f1 and f2: using only the data up to the end of 2008, we obtain dP/dt1=(1.34+/-0.04)x10^-12^ and dP/dt2=(1.62+/-0.22)x10^-12^. The long-term variation of the two main pulsation periods (and the change of sign of dP/dt_1_) is visible also in direct measurements made over several years. The absence of peaks near f1 in the Fourier transform and the secondary peak close to f2 confirm a previous identification as l=0 and l=1, respectively, and suggest a stellar rotation period of about 40 days. The new data allow constraining the main g-mode pulsation periods of the star.
- ID:
- ivo://CDS.VizieR/J/PASP/133/H4201
- Title:
- Times of maxima for 23 delta Scuti stars
- Short Name:
- J/PASP/133/H4201
- Date:
- 17 Jan 2022 00:25:09
- Publisher:
- CDS
- Description:
- The multi-color CCD photometric study of 27 delta Scuti stars is presented. By using approximately three years of photometric observations, we obtained the times of maxima and magnitude changes during the observation time interval for each star. The ephemeris of our delta Scuti star was calculated based on the Markov Chain Monte Carlo (MCMC) method using the observed times of maxima and the period of star' oscillations. We used the Gaia EDR3 parallaxes to calculate the luminosities and also the absolute magnitudes of these delta Scuti stars. The fundamental physical parameters of all studied stars, such as mass and radius, were estimated. We determined the pulsation modes of the stars based on the pulsation constants. Moreover, the period-luminosity relation of delta Scuti stars was investigated and discussed. Then, by using a machine learning classification, new P-L relations for fundamental and overtone modes are presented.
- ID:
- ivo://CDS.VizieR/J/PASP/125/639
- Title:
- Times of Maxima for the SX Phe star BL Cam
- Short Name:
- J/PASP/125/639
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A total of 73 new times of maximum light for BL Cam were observed through the years 2005 to 2011, which are combined with 1392 times of maxima taken from literature. A more accurate period of 0.039097912(1) days was found, and an updated linear ephemeris is presented. This newly presented linear ephemeris was used to calculate revised O minus C values, which were fitted with a parabolic curve to measure the rate of change of the pulsation period, found to be (1/P)(dP/dt)=1.37+/-0.02x10^-7yr^-1. Although the parabolic fit has a physical interpretation, it is noted that a cubic more appropriately fits the behavior of the O minus C diagram.
