- ID:
- ivo://CDS.VizieR/J/ApJ/749/79
- Title:
- Transition disks. II. Southern MoC
- Short Name:
- J/ApJ/749/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Transition disk objects are pre-main-sequence stars with little or no near-IR excess and significant far-IR excess, implying inner opacity holes in their disks. Here we present a multifrequency study of transition disk candidates located in Lupus I, III, IV, V, VI, Corona Australis, and Scorpius. Complementing the information provided by Spitzer with adaptive optics (AO) imaging (NaCo, VLT), submillimeter photometry (APEX), and echelle spectroscopy (Magellan, Du Pont Telescopes), we estimate the multiplicity, disk mass, and accretion rate for each object in our sample in order to identify the mechanism potentially responsible for its inner hole. We find that our transition disks show a rich diversity in their spectral energy distribution morphology, have disk masses ranging from <~1 to 10M_JUP_, and accretion rates ranging from <~10^-11^ to 10^-7.7^M_{sun}_/yr. Of the 17 bona fide transition disks in our sample, three, nine, three, and two objects are consistent with giant planet formation, grain growth, photoevaporation, and debris disks, respectively. Two disks could be circumbinary, which offers tidal truncation as an alternative origin of the inner hole.
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- ID:
- ivo://CDS.VizieR/J/AJ/143/95
- Title:
- Transit light curves of HAT-P-12
- Short Name:
- J/AJ/143/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new photometric data of the transiting planet HAT-P-12b observed in 2011. Our three transit curves are modeled using the JKTEBOP code and adopting the quadratic limb-darkening law. Including our measurements, 18 transit times spanning about 4.2yr were used to determine the improved ephemeris with a transit epoch of 2454187.85560+/-0.00011BJD and an orbital period of 3.21305961+/-0.00000035days. The physical properties of the star-planet system are computed using empirical calibrations from eclipsing binary stars and stellar evolutionary models, combined with both our transit parameters and previously known spectroscopic results. We found that the absolute dimensions of the host star are M_A_=0.73+/-0.02M{sun}, R_A_=0.70+/-0.01R_{sun}_, log g_A_=4.61+/-0.02, p_A_=2.10+/-0.09{rho}{sun}, and L_A_=0.21+/-0.01L_{sun}_. The planetary companion has M_b_=0.21+/-0.01M_{Jup}_, R_b_=0.94+/-0.01R_{Jup}_, log g_b_=2.77+/-0.02, {rho}_b_=0.24+/-0.01{rho}_{Jup}_, and T_eq_=960+/-14K. Our results agree well with standard models of irradiated gas giants with a core mass of 11.3M_{earth}_.
- ID:
- ivo://CDS.VizieR/J/AJ/156/218
- Title:
- Transit light curves of TRAPPIST-1 planets
- Short Name:
- J/AJ/156/218
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The TRAPPIST-1 planetary system provides an exceptional opportunity for the atmospheric characterization of temperate terrestrial exoplanets with the upcoming James Webb Space Telescope (JWST). Assessing the potential impact of stellar contamination on the planets' transit transmission spectra is an essential precursor to this characterization. Planetary transits themselves can be used to scan the stellar photosphere and to constrain its heterogeneity through transit depth variations in time and wavelength. In this context, we present our analysis of 169 transits observed in the optical from space with K2 and from the ground with the SPECULOOS and Liverpool telescopes. Combining our measured transit depths with literature results gathered in the mid-/near-IR with Spitzer/IRAC and HST/WFC3, we construct the broadband transmission spectra of the TRAPPIST-1 planets over the 0.8-4.5 {mu}m spectral range. While planet b, d, and f spectra show some structures at the 200-300 ppm level, the four others are globally flat. Even if we cannot discard their instrumental origins, two scenarios seem to be favored by the data: a stellar photosphere dominated by a few high-latitude giant (cold) spots, or, alternatively, by a few small and hot (3500-4000 K) faculae. In both cases, the stellar contamination of the transit transmission spectra is expected to be less dramatic than predicted in recent papers. Nevertheless, based on our results, stellar contamination can still be of comparable or greater order than planetary atmospheric signals at certain wavelengths. Understanding and correcting the effects of stellar heterogeneity therefore appears essential for preparing for the exploration of TRAPPIST-1 with JWST.
- ID:
- ivo://CDS.VizieR/J/A+A/557/A30
- Title:
- Transits of HAT-P-16 and WASP-21
- Short Name:
- J/A+A/557/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first photometric follow-up of the transiting planet HAT-P-16 b, and new photometric observations of WASP-21 b, obtained simultaneously with two medium-class telescopes located in different countries, using the telescope defocussing technique. We modeled these and other published data in order to estimate the physical parameters of the two planetary systems.
- ID:
- ivo://CDS.VizieR/J/AJ/159/120
- Title:
- Transit time of K2-146b and K2-146c with K2 and HPF
- Short Name:
- J/AJ/159/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- K2-146 is a cool, 0.358M_{sun}_ dwarf that was found to host a mini-Neptune with a 2.67day period. The planet exhibited strong transit timing variations (TTVs) of greater than 30minutes, indicative of the presence of an additional object in the system. Here we report the discovery of the previously undetected outer planet in the system, K2-146c, using additional photometric data. K2-146c was found to have a grazing transit geometry and a 3.97day period. The outer planet was only significantly detected in the latter K2 campaigns presumably because of precession of its orbital plane. The TTVs of K2-146b and c were measured using observations spanning a baseline of almost 1200days. We found strong anti-correlation in the TTVs, suggesting the two planets are gravitationally interacting. Our TTV and transit model analyses revealed that K2-146b has a radius of 2.25{+/-}0.10R_{earth}_ and a mass of 5.6{+/-}0.7M_{earth}_, whereas K2-146c has a radius of 2.59_-0.39_^+1.81^R_{earth} and a mass of 7.1{+/-}0.9M_{earth}_. The inner and outer planets likely have moderate eccentricities of e=0.14{+/-}0.07 and 0.16{+/-}0.07, respectively. Long-term numerical integrations of the two-planet orbital solution show that it can be dynamically stable for at least 2Myr. We show that the resonance angles of the planet pair are librating, which may be an indication that K2-146b and c are in a 3:2 mean motion resonance. The orbital architecture of the system points to a possible convergent migration origin.
- ID:
- ivo://CDS.VizieR/J/AJ/159/150
- Title:
- Transit times of 11 hot Jupiters
- Short Name:
- J/AJ/159/150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Many of the known hot Jupiters are formally unstable to tidal orbital decay. The only hot Jupiter for which orbital decay has been directly detected is WASP-12, for which transit-timing measurements spanning more than a decade have revealed that the orbital period is decreasing at a rate of dP/dt~10^-9^, corresponding to a reduced tidal quality factor of about 2x10^5^. Here, we present a compilation of transit-timing data for WASP-12 and 11 other systems that are especially favorable for detecting orbital decay: KELT-16; WASP-18, 19, 43, 72, 103, 114, and 122; HAT-P-23; HATS-18; and OGLE-TR-56. For most of these systems we present new data that extend the time baseline over which observations have been performed. None of the systems besides WASP-12 display convincing evidence for period changes, with typical upper limits on dP/dt on the order of 10^-9^ or 10^-10^, and lower limits on the reduced tidal quality factor on the order of 10^5^. One possible exception is WASP-19, which shows a statistically significant trend, although it may be a spurious effect of starspot activity.
- ID:
- ivo://CDS.VizieR/J/AJ/162/210
- Title:
- Transit Time Vartiations (TTVs) of WASP-43
- Short Name:
- J/AJ/162/210
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- WASP-43b is one of the most important candidates for detecting an orbital decay. We investigate pieces of evidence for this expectation as variations in its transit timings, based on the ground and space observations. The data set includes the transit observations at the TUBITAK National Observatory of Turkey and Transiting Exoplanet Survey Satellite (TESS). We present a global model of the system, based on the most precise photometry from space, ground, and archival radial velocity data. Using the homogenized data set and modeled light curves, we measure the mid-transit times for WASP-43b. Our analysis agrees with a linear ephemeris for which we refine the light elements for future observations of the system. However, there is a negative difference between the transit timings derived from TESS data in two sectors (9 and 35) and a hint of an orbital period decrease in the entire data set. Both findings are statistically insignificant due to the short baseline of observations, which prevents us from drawing firm conclusions about the orbital decay of this ultra-short-period planet. However, assuming the effect of this decrease of the period in the planet's orbit, we derive a lower limit for the reduced tidal quality factor as Q*'>(4.01{+/-}1.15)x10^5^ from the best-fitting quadratic function. Finally, we calculate a probable rotational period for this system as 7.52days from the out-of-transit flux variation in the TESS light curves due to spot modulation.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A138
- Title:
- TRAPPIST-1 analogue stars TESS light curves
- Short Name:
- J/A+A/650/A138
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- As more exoplanets are being discovered around ultracool dwarfs, understanding their magnetic activity - and the implications for habitability - is of prime importance. To find stellar flares and photometric signatures related to starspots, continuous monitoring is necessary, which can be achieved with spaceborn observatories like the Transiting Exoplanet Survey Satellite (TESS). We present an analysis of TRAPPIST-1 like ultracool dwarfs with TESS full- frame image photometry from the first two years of the primary mission. A volume-limited sample up to 50pc is constructed consisting of 339 stars closer than 0.5mag to TRAPPIST-1 on the Gaia colour-magnitude diagram. The 30-min cadence TESS light curves of 248 stars were analysed, searching for flares and rotational modulation caused by starspots. The composite flare frequency distribution of the 94 identified flares shows a power law index similar to TRAPPIST-1, and contains flares up to E_TESS_=3*10^33^erg. Rotational periods shorter than 5 days were determined for 42 stars, sampling the regime of fast rotators. The ages of 88 stars from the sample were estimated using kinematic information. A weak correlation between rotational period and age is observed, which is consistent with magnetic braking.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A26
- Title:
- TrES-3b UBVIz' light curves
- Short Name:
- J/A+A/608/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Transit events of extrasolar planets offer the opportunity to study the composition of their atmospheres. Previous work on transmission spectroscopy of the close-in gas giant TrES-3 b revealed an increase in absorption towards blue wavelengths of very large amplitude in terms of atmospheric pressure scale heights, too large to be explained by Rayleigh- scattering in the planetary atmosphere. We present a follow-up study of the optical transmission spectrum of the hot Jupiter TrES-3 b to investigate the strong increase in opacity towards short wavelengths found by a previous study. Furthermore, we aim to estimate the effect of stellar spots on the transmission spectrum. This work uses previously published long slit spectroscopy transit data of the Gran Telescopio Canarias (GTC) and published broad band observations as well as new observations in different bands from the near-UV to the near-IR, for a homogeneous transit light curve analysis. Additionally, a long-term photometric monitoring of the TrES-3 host star was performed. Our newly analysed GTC spectroscopic transit observations show a slope of much lower amplitude than previous studies. We conclude from our results the previously reported increasing signal towards short wavelengths is not intrinsic to the TrES-3 system. Furthermore, the broad band spectrum favours a flat spectrum. Long-term photometric monitoring rules out a significant modification of the transmission spectrum by unocculted star spots.
- ID:
- ivo://CDS.VizieR/J/ApJ/717/1067
- Title:
- Triggered star formation in SFO 38
- Short Name:
- J/ApJ/717/1067
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have investigated the young stellar population in and around SFO 38, one of the massive globules located in the northern part of the Galactic HII region IC 1396, using the Spitzer IRAC and MIPS observations (3.6-24um), and followed up with ground-based optical photometric and spectroscopic observations. Based on the IRAC and MIPS colors and H{alpha} emission, we identify ~45 young stellar objects (Classes 0/I/II) and 13 probable pre-main-sequence candidates. We derive the spectral types (mostly K- and M-type stars), effective temperatures, and individual extinction of the relatively bright and optically visible Class II objects. Using the width of the H{alpha} emission line measured at 10% peak intensity, we derive the mass accretion rates of individual objects to be between 10^-10^ and 10^-8^M_{sun}_/yr.
