412 research outputs found
An Accurate Mass Determination for Kepler-1655b, a Moderately Irradiated World with a Significant Volatile Envelope
We present the confirmation of a small, moderately irradiated (F = 155 ± 7 Fâ) Neptune with a substantial gas envelope in a P = 11.8728787 ± 0.0000085 day orbit about a quiet, Sun-like G0V star Kepler-1655. Based on our analysis of the Kepler light curve, we determined Kepler-1655b's radius to be 2.213 ± 0.082 Râ. We acquired 95 high-resolution spectra with Telescopio Nazionale Galileo/HARPS-N, enabling us to characterize the host star and determine an accurate mass for Kepler-1655b of 5.0±^(3.1)_(2.8) Mâ via Gaussian-process regression. Our mass determination excludes an Earth-like composition with 98% confidence. Kepler-1655b falls on the upper edge of the evaporation valley, in the relatively sparsely occupied transition region between rocky and gas-rich planets. It is therefore part of a population of planets that we should actively seek to characterize further
A reproducible open platform for a collective process - Translating CIDOC CRM 7.1.2 in French
he conference present a reproducible open platform supported collective process for the full translation of the CIDOC CRM 7.1.2/3 (future ISO version). The project of translation is conceived and held following FAIR principles and in a fully reproducible way. It also aim at building a CIDOC CRM user community among Digital Humanity research institutions through considering the translation process as a learning experience, a collaboration project and moreover as Digital Humanities research project
Compact SQUID realized in a double layer graphene heterostructure
Two-dimensional systems that host one-dimensional helical states are exciting
from the perspective of scalable topological quantum computation when coupled
with a superconductor. Graphene is particularly promising for its high
electronic quality, versatility in van der Waals heterostructures and its
electron and hole-like degenerate 0 Landau level. Here, we study a compact
double layer graphene SQUID (superconducting quantum interference device),
where the superconducting loop is reduced to the superconducting contacts,
connecting two parallel graphene Josephson junctions. Despite the small size of
the SQUID, it is fully tunable by independent gate control of the Fermi
energies in both layers. Furthermore, both Josephson junctions show a skewed
current phase relationship, indicating the presence of superconducting modes
with high transparency. In the quantum Hall regime we measure a well defined
conductance plateau of 2 an indicative of counter propagating edge
channels in the two layers. Our work opens a way for engineering topological
superconductivity by coupling helical edge states, from graphene's
electron-hole degenerate 0 Landau level via superconducting contacts.Comment: 38 pages, 12 figure
The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet
Kepler-10b was the first rocky planet detected by the Kepler satellite and
con- firmed with radial velocity follow-up observations from Keck-HIRES. The
mass of the planet was measured with a precision of around 30%, which was
insufficient to constrain models of its internal structure and composition in
detail. In addition to Kepler-10b, a second planet transiting the same star
with a period of 45 days was sta- tistically validated, but the radial
velocities were only good enough to set an upper limit of 20 Mearth for the
mass of Kepler-10c. To improve the precision on the mass for planet b, the
HARPS-N Collaboration decided to observe Kepler-10 intensively with the HARPS-N
spectrograph on the Telescopio Nazionale Galileo on La Palma. In to- tal, 148
high-quality radial-velocity measurements were obtained over two observing
seasons. These new data allow us to improve the precision of the mass
determina- tion for Kepler-10b to 15%. With a mass of 3.33 +/- 0.49 Mearth and
an updated radius of 1.47 +0.03 -0.02 Rearth, Kepler-10b has a density of 5.8
+/- 0.8 g cm-3, very close to the value -0.02 predicted by models with the same
internal structure and composition as the Earth. We were also able to determine
a mass for the 45-day period planet Kepler-10c, with an even better precision
of 11%. With a mass of 17.2 +/- 1.9 Mearth and radius of 2.35 +0.09 -0.04
Rearth, -0.04 Kepler-10c has a density of 7.1 +/- 1.0 g cm-3. Kepler-10c
appears to be the first strong evidence of a class of more massive solid
planets with longer orbital periods.Comment: 44 pages, 8 figures, accepted for publication in Ap
Further Insights into the Gut Microbiota of Cowâs Milk Allergic Infants: Analysis of Microbial Functionality and Its Correlation with Three Fecal Biomarkers
Cowâs milk allergy (CMA) is one of the most prevalent food allergies in children. Several studies have demonstrated that gut microbiota influences the acquisition of oral tolerance to food antigens at initial stages of life. Changes in the gut microbiota composition and/or functionality (i.e., dysbiosis) have been linked to inadequate immune system regulation and the emergence of pathologies. Moreover, omic sciences have become an essential tool for the analysis of the gut microbiota. On the other hand, the use of fecal biomarkers for the diagnosis of CMA has recently been reviewed, with fecal calprotectin, α-1 antitrypsin, and lactoferrin being the most relevant. This study aimed at evaluating functional changes in the gut microbiota in the feces of cowâs milk allergic infants (AI) compared to control infants (CI) by metagenomic shotgun sequencing and at correlating these findings with the levels of fecal biomarkers (α-1 antitrypsin, lactoferrin, and calprotectin) by an integrative approach. We have observed differences between AI and CI groups in terms of fecal protein levels and metagenomic analysis. Our findings suggest that AI have altered glycerophospholipid metabolism as well as higher levels of lactoferrin and calprotectin that could be explained by their allergic status.This research was funded by Instituto de Salud Carlos III (PI17/01087 and PI20/01366) and FundaciĂłn Sociedad Española de Alergia e InmunologĂa ClĂnica (FSEAIC_2016). It was co-funded by the European Regional Development Fund âInvesting in your futureâ for the thematic network and co-operative research centers ARADyAL RD16/0006/0015 and RD16/0006/0026. T.B-T is supported by FPI-CEU predoctoral fellowship. D.B. acknowledges financial support from Instituto de Salud Carlos III (PI19/00044)
Identifying exoplanets with deep learning. IV. Removing stellar activity signals from radial velocity measurements using neural networks
Funding: This project has received funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation program (SCORE grant agreement No. 851555). A.C.C. acknowledges support from the Science and Technology Facilities Council (STFC) consolidated grant No. ST/R000824/1 and UKSA grant ST/R003203/1. R.D.H. is funded by the UK Science and Technology Facilities Council (STFC)âs Ernest Rutherford Fellowship (grant number ST/V004735/1). M.P. acknowledges financial support from the ASI-INAF agreement No. 2018-16-HH.0. A.M. acknowledges support from the senior Kavli Institute Fellowships.Exoplanet detection with precise radial velocity (RV) observations is currently limited by spurious RV signals introduced by stellar activity. We show that machine-learning techniques such as linear regression and neural networks can effectively remove the activity signals (due to starspots/faculae) from RV observations. Previous efforts focused on carefully filtering out activity signals in time using modeling techniques like Gaussian process regression. Instead, we systematically remove activity signals using only changes to the average shape of spectral lines, and use no timing information. We trained our machine-learning models on both simulated data (generated with the SOAP 2.0 software) and observations of the Sun from the HARPS-N Solar Telescope. We find that these techniques can predict and remove stellar activity both from simulated data (improving RV scatter from 82 to 3 cm sâ1) and from more than 600 real observations taken nearly daily over 3 yr with the HARPS-N Solar Telescope (improving the RV scatter from 1.753 to 1.039 m sâ1, a factor of âŒ1.7 improvement). In the future, these or similar techniques could remove activity signals from observations of stars outside our solar system and eventually help detect habitable-zone Earth-mass exoplanets around Sun-like stars.Publisher PDFPeer reviewe
Kepler-21b: A Rocky Planet Around a V = 8.25 Magnitude Star
HD 179070, aka Kepler-21, is a V = 8.25 F6IV star and the brightest exoplanet host discovered by Kepler. An early detailed analysis by Howell et al. (2012) of the first thirteen months (Q0 - Q5) of Kepler light curves revealed transits of a planetary companion, Kepler-21b, with a radius of about 1.60 ± 0.04 Râ and an orbital period of about 2.7857 days. However, they could not determine the mass of the planet from the initial radial velocity observations with Keck-HIRES, and were only able to impose a 2Ï upper limit of 10 Mâ. Here we present results from the analysis of 82 new radial velocity observations of this system obtained with HARPS-N, together with the existing 14 HIRES data points. We detect the Doppler signal of Kepler-21b with a radial velocity semi-amplitude K = 2.00 ± 0.65 m s-1, which corresponds to a planetary mass of 5.1 ± 1.7 Mâ. We also measure an improved radius for the planet of 1.639 +0.019/-0.015 Râ, in agreement with the radius reported by Howell et al. (2012). We conclude that Kepler-21b, with a density of 6.4 ± 2.1 g cm-3, belongs to the population of small, â€6 Mâ planets with iron and magnesium silicate interiors, which have lost the majority of their envelope volatiles via stellar winds or gravitational escape. The RV analysis presented in this paper serves as example of the type of analysis that will be necessary to confirm the masses of TESS small planet candidates.PostprintPeer reviewe
TOI-1695 b:A Water World Orbiting an Early-M Dwarf in the Planet Radius Valley
Characterizing the bulk compositions of transiting exoplanets within the M dwarf radius valley offers a unique means to establish whether the radius valley emerges from an atmospheric mass-loss process or is imprinted by planet formation itself. We present the confirmation of such a planet orbiting an early-M dwarf (Tmag = 11.0294 ± 0.0074, Ms = 0.513 ± 0.012 Mâ, Rs = 0.515 ± 0.015 Râ, and Teff = 3690 ± 50 K): TOI-1695 b (P = 3.13 days and Rp = 1.90â0.14+0.16 Râ ). TOI-1695 bâs radius and orbital period situate the planet between model predictions from thermally driven mass loss versus gas depleted formation, offering an important test case for radius valley emergence models around early-M dwarfs. We confirm the planetary nature of TOI-1695 b based on five sectors of TESS data and a suite of follow-up observations including 49 precise radial velocity measurements taken with the HARPS-N spectrograph. We measure a planetary mass of 6.36 ± 1.00 Mâ, which reveals that TOI-1695 b is inconsistent with a purely terrestrial composition of iron and magnesium silicate, and instead is likely a water-rich planet. Our finding that TOI-1695 b is not terrestrial is inconsistent with the planetary system being sculpted by thermally driven mass loss. We present a statistical analysis of seven well-characterized planets within the M dwarf radius valley demonstrating that a thermally driven mass-loss scenario is unlikely to explain this population.</p
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