67 research outputs found
A rocky planet transiting a nearby low-mass star
M-dwarf stars -- hydrogen-burning stars that are smaller than 60 per cent of
the size of the Sun -- are the most common class of star in our Galaxy and
outnumber Sun-like stars by a ratio of 12:1. Recent results have shown that M
dwarfs host Earth-sized planets in great numbers: the average number of M-dwarf
planets that are between 0.5 to 1.5 times the size of Earth is at least 1.4 per
star. The nearest such planets known to transit their star are 39 parsecs away,
too distant for detailed follow-up observations to measure the planetary masses
or to study their atmospheres. Here we report observations of GJ 1132b, a
planet with a size of 1.2 Earth radii that is transiting a small star 12
parsecs away. Our Doppler mass measurement of GJ 1132b yields a density
consistent with an Earth-like bulk composition, similar to the compositions of
the six known exoplanets with masses less than six times that of the Earth and
precisely measured densities. Receiving 19 times more stellar radiation than
the Earth, the planet is too hot to be habitable but is cool enough to support
a substantial atmosphere, one that has probably been considerably depleted of
hydrogen. Because the host star is nearby and only 21 per cent the radius of
the Sun, existing and upcoming telescopes will be able to observe the
composition and dynamics of the planetary atmosphere.Comment: Published in Nature on 12 November 2015, available at
http://dx.doi.org/10.1038/nature15762. This is the authors' version of the
manuscrip
Local iron homeostasis in the breast ductal carcinoma microenvironment
Abstract
BACKGROUND:
While the deregulation of iron homeostasis in breast epithelial cells is acknowledged, iron-related alterations in stromal inflammatory cells from the tumor microenvironment have not been explored.
METHODS:
Immunohistochemistry for hepcidin, ferroportin 1 (FPN1), transferrin receptor 1 (TFR1) and ferritin (FT) was performed in primary breast tissues and axillary lymph nodes in order to dissect the iron-profiles of epithelial cells, lymphocytes and macrophages. Furthermore, breast carcinoma core biopsies frozen in optimum cutting temperature (OCT) compound were subjected to imaging flow cytometry to confirm FPN1 expression in the cell types previously evaluated and determine its cellular localization.
RESULTS:
We confirm previous results by showing that breast cancer epithelial cells present an 'iron-utilization phenotype' with an increased expression of hepcidin and TFR1, and decreased expression of FT. On the other hand, lymphocytes and macrophages infiltrating primary tumors and from metastized lymph nodes display an 'iron-donor' phenotype, with increased expression of FPN1 and FT, concomitant with an activation profile reflected by a higher expression of TFR1 and hepcidin. A higher percentage of breast carcinomas, compared to control mastectomy samples, present iron accumulation in stromal inflammatory cells, suggesting that these cells may constitute an effective tissue iron reservoir. Additionally, not only the deregulated expression of iron-related proteins in epithelial cells, but also on lymphocytes and macrophages, are associated with clinicopathological markers of breast cancer poor prognosis, such as negative hormone receptor status and tumor size.
CONCLUSIONS:
The present results reinforce the importance of analyzing the tumor microenvironment in breast cancer, extending the contribution of immune cells to local iron homeostasis in the tumor microenvironment context.info:eu-repo/semantics/publishedVersio
Identification of carbon dioxide in an exoplanet atmosphere
Carbon dioxide (CO2) is a key chemical species that is found in a wide range of planetary atmospheres. In the context of exoplanets, CO2 is an indicator of the metal enrichment (that is, elements heavier than helium, also called ‘metallicity’)1–3, and thus the formation processes of the primary atmospheres of hot gas giants4–6. It is also one of the most promising species to detect in the secondary atmospheres of terrestrial exoplanets7–9. Previous photometric measurements of transiting planets with the Spitzer Space Telescope have given hints of the presence of CO2, but have not yielded definitive detections owing to the lack of unambiguous spectroscopic identification10–12. Here we present the detection of CO2 in the atmosphere of the gas giant exoplanet WASP-39b from transmission spectroscopy observations obtained with JWST as part of the Early Release Science programme13,14. The data used in this study span 3.0–5.5 micrometres in wavelength and show a prominent CO2 absorption feature at 4.3 micrometres (26-sigma significance). The overall spectrum is well matched by one-dimensional, ten-times solar metallicity models that assume radiative–convective–thermochemical equilibrium and have moderate cloud opacity. These models predict that the atmosphere should have water, carbon monoxide and hydrogen sulfide in addition to CO2, but little methane. Furthermore, we also tentatively detect a small absorption feature near 4.0 micrometres that is not reproduced by these models
Exoplanet mass estimation for a sample of targets for the <i>Ariel</i> mission
Ariel’s ambitious goal to survey a quarter of known exoplanets will transform our knowledge of planetary atmospheres. Masses measured directly with the radial velocity technique are essential for well determined planetary bulk properties. Radial velocity masses will provide important checks of masses derived from atmospheric fits or alternatively can be treated as a fixed input parameter to reduce possible degeneracies in atmospheric retrievals. We quantify the impact of stellar activity on planet mass recovery for the Ariel mission sample using Sun-like spot models scaled for active stars combined with other noise sources. Planets with necessarily well-determined ephemerides will be selected for characterisation with Ariel. With this prior requirement, we simulate the derived planet mass precision as a function of the number of observations for a prospective sample of Ariel targets. We find that quadrature sampling can significantly reduce the time commitment required for follow-up RVs, and is most effective when the planetary RV signature is larger than the RV noise. For a typical radial velocity instrument operating on a 4 m class telescope and achieving 1 m s−1 precision, between ~17% and ~ 37% of the time commitment is spent on the 7% of planets with mass Mp ⊕. In many low activity cases, the time required is limited by asteroseismic and photon noise. For low mass or faint systems, we can recover masses with the same precision up to ~3 times more quickly with an instrumental precision of ~10 cm s−1
TESS Discovery of a Super-Earth and Three Sub-Neptunes Hosted by the Bright, Sun-like Star HD 108236
We report the discovery and validation of four extrasolar planets hosted by the nearby, bright, Sun-like (G3V) star HD 108236 using data from the Transiting Exoplanet Survey Satellite (TESS). We present transit photometry, reconnaissance, and precise Doppler spectroscopy, as well as high-resolution imaging, to validate the planetary nature of the objects transiting HD 108236, also known as the TESS Object of Interest (TOI) 1233. The innermost planet is a possibly rocky super-Earth with a period of days and has a radius of 1.586 ± 0.098 R⊕. The outer planets are sub-Neptunes, with potential gaseous envelopes, having radii of R⊕, 2.72 ± 0.11 R⊕, and R⊕ and periods of days, days, and days, respectively. With V and Ks magnitudes of 9.2 and 7.6, respectively, the bright host star makes the transiting planets favorable targets for mass measurements and, potentially, for atmospheric characterization via transmission spectroscopy. HD 108236 is the brightest Sun-like star in the visual (V) band known to host four or more transiting exoplanets. The discovered planets span a broad range of planetary radii and equilibrium temperatures and share a common history of insolation from a Sun-like star (R⋆ = 0.888 ± 0.017 R⊙, Teff = 5730 ± 50 K), making HD 108236 an exciting, opportune cosmic laboratory for testing models of planet formation and evolution
Combination of searches for heavy spin-1 resonances using 139 fb−1 of proton-proton collision data at s = 13 TeV with the ATLAS detector
A combination of searches for new heavy spin-1 resonances decaying into different pairings of W, Z, or Higgs bosons, as well as directly into leptons or quarks, is presented. The data sample used corresponds to 139 fb−1 of proton-proton collisions at
= 13 TeV collected during 2015–2018 with the ATLAS detector at the CERN Large Hadron Collider. Analyses selecting quark pairs (qq, bb,
, and tb) or third-generation leptons (τν and ττ) are included in this kind of combination for the first time. A simplified model predicting a spin-1 heavy vector-boson triplet is used. Cross-section limits are set at the 95% confidence level and are compared with predictions for the benchmark model. These limits are also expressed in terms of constraints on couplings of the heavy vector-boson triplet to quarks, leptons, and the Higgs boson. The complementarity of the various analyses increases the sensitivity to new physics, and the resulting constraints are stronger than those from any individual analysis considered. The data exclude a heavy vector-boson triplet with mass below 5.8 TeV in a weakly coupled scenario, below 4.4 TeV in a strongly coupled scenario, and up to 1.5 TeV in the case of production via vector-boson fusion
Early Release Science of the exoplanetWASP-39b with JWST NIRISS
This is the author accepted manuscript. The final version is available from Nature Research via the DOI in this recordData Availability:
The raw data from this study are publicly available via the Space Science Telescope Institute's
Mikulski Archive for Space Telescopes (https://archive.stsci.edu/). The data which was used to
create all of the figures in this manuscript are freely available on Zenodo and GitHub (Zenodo
Link;https://github.com/afeinstein20/wasp39b_niriss_paper). All additional data is available upon
request.Code Availability:
The following are open-source pipelines written in Python that are available either through the
Python Package Index (PyPI) or GitHub that were used throughout this work:
Eureka! (https://github.com/kevin218/Eureka); nirHiss (https://github.com/afeinstein20/nirhiss);
supreme-SPOON (https://github.com/radicamc/supreme-spoon); transitspectroscopy
(https://github.com/nespinoza/transitspectroscopy/tree/dev); iraclis (https://github.com/uclexoplanets/Iraclis); juliet (https://github.com/nespinoza/juliet); chromatic
(https://github.com/zkbt/chromatic); chromatic_fitting
(https://github.com/catrionamurray/chromatic_fitting); ExoTiC-LD54, 121
(https://github.com/Exo-TiC/ExoTiC-LD); ExoTETHyS122 (https://github.com/uclexoplanets/ExoTETHyS); PICASO88,89 (https://github.com/natashabatalha/picaso); Virga94, 95
(https://github.com/natashabatalha/virga); CHIMERA (https://github.com/mrline/CHIMERA);
PyMultiNest (https://github.com/JohannesBuchner/PyMultiNest); MultiNest
(https://github.com/JohannesBuchner/MultiNest)The Saturn-mass exoplanet WASP-39b has been the subject of extensive efforts to determine its atmospheric properties using transmission spectroscopy. However, these efforts have been hampered by modelling degeneracies between composition and cloud properties that are caused by limited data quality. Here, we present the transmission spectrum of WASP-39 b obtained using the SOSS mode of the NIRISS instrument on JWST. This spectrum spans 0.6–2.8m in wavelength and reveals multiple water absorption bands, the potassium resonance doublet, and signatures of clouds. The precision and broad wavelength coverage of NIRISS-SOSS allows us to break model degeneracies between cloud properties and the atmospheric composition of WASP-39b, favouring a heavy element enhancement (“metallicity”) of ~10–30x the solar value, a sub-solar carbon-to-oxygen (C/O) ratio, and a solar-to-super-solar potassium-to-oxygen (K/O) ratio. The observations are also best explained by wavelength-dependent, non-gray clouds with inhomogeneous coverage of the planet’s terminator.Leverhulme TrustUK Research and Innovatio
Early Release Science of the exoplanet WASP-39b with JWST NIRSpec G395H
This is the author accepted manuscript. The final version is available from Nature Research via the DOI in this recordData Availability:
The data used in this paper are associated with JWST program ERS 1366 (observation #4) and
are available from the Mikulski Archive for Space Telescopes (https://mast.stsci.edu). Science
data processing version (SDP_VER) 2022_2a generated the uncalibrated data that we
downloaded from MAST. We used JWST Calibration Pipeline software version (CAL_VER)
1.5.3 with modifications described in the text. We used calibration reference data from context
(CRDS_CTX) 0916, except as noted in the text. All the data and models presented in this
publication can be found at 10.5281/zenodo.7185300.Code Availability:
The codes used in this publication to extract, reduce and analyze the data are as follows;
STScI JWST Calibration pipeline45 (https://github.com/spacetelescope/jwst), Eureka!53
(https://eurekadocs.readthedocs.io/en/latest/), ExoTiC-JEDI47 (https://github.com/ExoTiC/ExoTiC-JEDI), juliet71 (https://juliet.readthedocs.io/en/latest/), Tiberius15,49,50,
transitspectroscopy51 (https://github.com/nespinoza/transitspectroscopy). In addition, these
made use of batman65 (http://lkreidberg.github.io/batman/docs/html/index.html), celerite86
(https://celerite.readthedocs.io/en/stable/), chromatic (https://zkbt.github.io/chromatic/),
Dynesty72 (https://dynesty.readthedocs.io/en/stable/index.html), emcee69
(https://emcee.readthedocs.io/en/stable/), exoplanet83 (https://docs.exoplanet.codes/en/latest/),
ExoTEP75–77, ExoTHETyS79 (https://github.com/ucl-exoplanets/ExoTETHyS), ExoTiCISM57 (https://github.com/Exo-TiC/ExoTiC-ISM), ExoTiC-LD58 (https://exoticld.readthedocs.io/en/latest/), george68 (https://george.readthedocs.io/en/latest/) JAX82
(https://jax.readthedocs.io/en/latest/), LMFIT70 (https://lmfit.github.io/lmfit-py/),
Pylightcurve78 (https://github.com/ucl-exoplanets/pylightcurve), Pymc3138
(https://docs.pymc.io/en/v3/index.html) and Starry84 (https://starry.readthedocs.io/en/latest/),
each of which use the standard python libraries astropy139,140, matplotlib141, numpy142,
pandas143, scipy64 and xarray144. The atmospheric models used to fit the data can be found at
ATMO[Tremblin2015,Drummond2016,Goyal2018,Goyal2020]88–91, PHOENIX92–94,
PICASO98,99 (https://natashabatalha.github.io/picaso/), Virga98,107
(https://natashabatalha.github.io/virga/), and gCMCRT115
(https://github.com/ELeeAstro/gCMCRT).Measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking the formation and evolution of exoplanetary systems. Access to an exoplanet’s chemical inventory requires high precision observations, often inferred from individual molecular detections with low-resolution space-based and high-resolution ground-based facilities. Here we report the medium-resolution (R≈600) transmission spectrum of an exoplanet atmosphere between 3–5 μm covering multiple absorption features for the Saturn-mass exoplanet WASP-39b, obtained with JWST NIRSpec G395H. Our observations achieve 1.46×
photon precision, providing an average transit depth uncertainty of 221 ppm per spectroscopic bin, and present minimal impacts from systematic effects. We detect significant absorption from CO2 (28.5σ
) and H2O (21.5σ
), and identify SO2 as the source of absorption at 4.1 μ
m (4.8σ
). Best-fit atmospheric models range between 3×
and 10×
solar metallicity, with sub-solar to solar C/O ratios. These results, including the detection of SO2, underscore the importance of characterising the chemistry in exoplanet atmospheres, and showcase NIRSpec G395H as an excellent mode for time series observations over this critical wavelength range.Science and Technology Facilities Council (STFC)UKR
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