16 research outputs found
New Mass and Radius Constraints on the LHS 1140 Planets -- LHS 1140 b is Either a Temperate Mini-Neptune or a Water World
The two-planet transiting system LHS 1140 has been extensively observed since
its discovery in 2017, notably with , HST, TESS, and ESPRESSO, placing
strong constraints on the parameters of the M4.5 host star and its small
temperate exoplanets, LHS 1140 b and c. Here, we reanalyse the ESPRESSO
observations of LHS 1140 with the novel line-by-line framework designed to
fully exploit the radial velocity content of a stellar spectrum while being
resilient to outlier measurements. The improved radial velocities, combined
with updated stellar parameters, consolidate our knowledge on the mass of LHS
1140 b (5.600.19 M) and LHS 1140 c (1.910.06 M)
with unprecedented precision of 3%. Transits from , HST, and TESS are
jointly analysed for the first time, allowing us to refine the planetary radii
of b (1.7300.025 R) and c (1.2720.026 R).
Stellar abundance measurements of refractory elements (Fe, Mg and Si) obtained
with NIRPS are used to constrain the internal structure of LHS 1140 b. This
planet is unlikely to be a rocky super-Earth as previously reported, but rather
a mini-Neptune with a 0.1% H/He envelope by mass or a water world with a
water-mass fraction between 9 and 19% depending on the atmospheric composition
and relative abundance of Fe and Mg. While the mini-Neptune case would not be
habitable, a water-abundant LHS 1140 b potentially has habitable surface
conditions according to 3D global climate models, suggesting liquid water at
the substellar point for atmospheres with relatively low CO concentration,
from Earth-like to a few bars.Comment: 31 pages, 18 figures, accepted for publication in ApJ
Hydromechanische Beitraege zum Betrieb von Kanalnetzen
Available from TIB Hannover: RO 9528(7) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
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Erratum: Giant Outer Transiting Exoplanet Mass (GOT ‘EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 yr, Highly Eccentric Orbit (AJ (2021) 162 (154) DOI: 10.3847/1538-3881/ac134b)
In the original analysis by Dalba et al. (2021) to confirm and characterize the Kepler-1704 system, an erroneous offset of 0.53878357713256 day was accidentally subtracted from the time stamps of the photometric measurements of this star acquired by the Kepler spacecraft. This photometry was then used in the comprehensive system modeling that yielded the final ephemeris of this exoplanet. As a result, parameters describing the timing of this planet’s orbit, most notably its conjunction (transit) time, were erroneously offset. This erratum serves to correct this error and the ephemeris of Kepler-1704 b. We added the 0.53878357713256 day offset to the time stamps of the Kepler photometry that was used in the original analysis. The corresponding flux values were unchanged. Besides the time stamps, we did not alter any other data product. We then conducted the joint modeling of the stellar and planetary parameters of the Kepler-1704 system using EXOFASTv2 (Eastman et al. 2019) exactly as described in Section 3 of Dalba et al. (2021). All priors and EXOFASTv2 settings were left as described in the original analysis. This new fit converged following the same criteria applied in the original analysis. We again observed a bimodality in mass and age of Kepler-1704 as described in Section 3.1 of Dalba et al. (2021). We selected the lower stellar mass solution just as before and calculated the updated stellar and planetary parameters, which are listed in Tables 1 and 2, respectively. The only parameter values in Tables 1 and 2 that changed significantly between Dalba et al. (2021) and this analysis are conjunction time (TC), periastron time (TP), and eclipse time (TS). This is expected given that the only change to the inputs to the EXOFASTv2 fit were the time stamps of the Kepler photometry. Changes for other parameters other than those listed above were only due to rounding error or small statistical variations in the Markov chain Monte Carlo analysis, and were all well within the 1σ uncertainties. Figure 1 shows the Kepler light curves with the updated time stamps and the updated best-fit models. This figure is analogous to Figure 5 of Dalba et al. (2021). Table 3 shows the updated predictions for the timing of future transits and periastron passages. Asexpected, the time of these events are shifted forward by the value of the time stamp offset relative to the corresponding times published in Table 4 of Dalba et al. (2021). We conducted two consistency checks of the new ephemeris for Kepler-1704 b. First, we accessed the Kepler Pre-search Data Conditioning Simple Aperture Photometry (PDCSAP; Jenkins et al. 2010; Smith et al. 2012; Stumpe et al. 2012) photometry of Kepler-1704 from Quarters 2 and 13 via the Mikulski Archive for Space Telescopes but we did not conduct any additional detrending. We inserted the unaltered PDCSAP transit light curves into the exact same EXOFASTv2 fit, which proceeded until convergence. The resulting orbital elements are consistent this with those listed in Table 2. Second, we accessed the Transit and Ephemeris Service on the NASA Exoplanet Archive15 and predicted future transit times of Kepler-1704 b using the planet candidate solution from the Kepler Quarter 1–17 Data Release 25 Supplemental Kepler Object of Interest Table. The resulting transit times forthe four events spanning the years 2023–2031 agreed with the transit times listed in Table 3 to within 1 minute