Néstor Espinoza
A5054374420- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Calibration and Measurement Techniques
- Spectroscopy and Laser Applications
- Atmospheric Ozone and Climate
- Adaptive optics and wavefront sensing
- Space Exploration and Technology
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- High-pressure geophysics and materials
- Astrophysical Phenomena and Observations
- Scientific Research and Discoveries
- Spacecraft and Cryogenic Technologies
- Geochemistry and Geologic Mapping
- Pulsars and Gravitational Waves Research
- Spacecraft Design and Technology
- Spectroscopy Techniques in Biomedical and Chemical Research
- Meteorological Phenomena and Simulations
- Distributed and Parallel Computing Systems
- Markov Chains and Monte Carlo Methods
- Semiconductor Lasers and Optical Devices
Space Telescope Science Institute
2019-2025
Johns Hopkins University
2022-2024
Lawrence Livermore National Laboratory
2024
Goddard Space Flight Center
2024
Schnörringen Telescope Science Institute
2023
Vattenfall (Sweden)
2023
Max Planck Institute for Astronomy
2018-2022
Cornell University
2022
Bishop's University
2022
Millennium Institute of Astrophysics
2014-2019
Here we present juliet, a versatile tool for the analysis of transits, radial-velocities, or both. juliet is built over many available tools modelling radial-velocities and stochastic processes (here modelled as Gaussian Processes; GPs) in order to deliver tool/wrapper which can be used transit photometry radial-velocity measurements from multiple instruments at same time, using nested sampling algorithms allows it not only perform thorough parameter space, but also model comparison via...
Limb-darkening is fundamental in determining transit lightcurve shapes, and typically modeled by a variety of laws that parametrize the intensity profile star being transited. Confronted with lightcurve, some authors fix parameters these laws, so-called limb-darkening coefficients (LDCs), while others prefer to let them float fitting procedure. Which best strategy, however, still unclear, as well how much each can bias retrieved parameters. In this work we attempt clarify those points first...
Abstract The James Webb Space Telescope (JWST) Early Release Observations (EROs) is a set of public outreach products created to mark the end commissioning and beginning science operations for JWST. Colloquially known as “Webb First Images Spectra,” these were intended demonstrate worldwide that JWST ready science, capable producing spectacular results. package was released on 2022 July 12 included images spectra galaxy cluster SMACS J0723.3-7327 distant lensed galaxies, interacting group...
Measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking formation evolution exoplanetary systems. Access to an exoplanet's chemical inventory requires high-precision observations, often inferred from individual molecular detections with low-resolution space-based high-resolution ground-based facilities. Here we report medium-resolution (R$\sim$600) transmission spectrum atmosphere between 3-5 $\mu$m covering multiple absorption...
Transmission spectroscopy provides insight into the atmospheric properties and consequently formation history, physics, chemistry of transiting exoplanets. However, obtaining precise inferences from transmission spectra requires simultaneously measuring strength shape multiple spectral absorption features a wide range chemical species. This has been challenging given precision wavelength coverage previous observatories. Here, we present spectrum Saturn-mass exoplanet WASP-39b obtained using...
Abstract Carbon dioxide (CO 2 ) is a key chemical species that found in wide range of planetary atmospheres. In the context exoplanets, CO an indicator metal enrichment (that is, elements heavier than helium, also called ‘metallicity’) 1–3 , and thus formation processes primary atmospheres hot gas giants 4–6 . It one most promising to detect secondary terrestrial exoplanets 7–9 Previous photometric measurements transiting planets with Spitzer Space Telescope have given hints presence but not...
Abstract Measuring the metallicity and carbon-to-oxygen (C/O) ratio in exoplanet atmospheres is a fundamental step towards constraining dominant chemical processes at work and, if equilibrium, revealing planet formation histories. Transmission spectroscopy (for example, refs. 1,2 ) provides necessary means by abundances of oxygen- carbon-bearing species; however, this requires broad wavelength coverage, moderate spectral resolution high precision, which, together, are not achievable with...
Abstract The Near-Infrared Spectrograph (NIRSpec) is one of the four focal plane instruments on James Webb Space Telescope. In this paper, we summarize in-orbit performance NIRSpec, as derived from data collected during its commissioning campaign and first few months nominal science operations. More specifically, discuss some critical hardware components such two NIRSpec Hawaii-2RG detectors, wheel mechanisms, microshutter array. We also accuracy target acquisition procedures used to...
Abstract Close-in giant exoplanets with temperatures greater than 2,000 K (‘ultra-hot Jupiters’) have been the subject of extensive efforts to determine their atmospheric properties using thermal emission measurements from Hubble Space Telescope (HST) and Spitzer 1–3 . However, previous studies yielded inconsistent results because small sizes spectral features limited information content data resulted in high sensitivity varying assumptions made treatment instrument systematics retrieval...
Abstract TRAPPIST-1 is a nearby system of seven Earth-sized, temperate, rocky exoplanets transiting Jupiter-sized M8.5V star, ideally suited for in-depth atmospheric studies. Each planet has been observed in transmission both from space and the ground, confidently rejecting cloud-free, hydrogen-rich atmospheres. Secondary eclipse observations b with JWST/MIRI are consistent little to no atmosphere given lack heat redistribution. Here we present first spectra obtained JWST/NIRISS over two...
Abstract Study Analysis Group 21 (SAG21) of NASA’s Exoplanet Exploration Program was organized to study the effect stellar contamination on space-based transmission spectroscopy, a method for studying exoplanetary atmospheres by measuring wavelength-dependent radius planet as it transits its star. Transmission spectroscopy relies precise understanding spectrum star being occulted. However, stars are not homogeneous, constant light sources but have temporally evolving photospheres and...
Abstract Clouds are prevalent in many of the exoplanet atmospheres that have been observed to date. For transiting exoplanets, we know if clouds present because they mute spectral features and cause wavelength-dependent scattering. While exact composition these is largely unknown, this information vital understanding chemistry energy budget planetary atmospheres. In work, observe one transit hot Jupiter WASP-17b with JWST’s Mid-Infrared Instrument Low Resolution Spectrometer generate a...
Abstract Hot Jupiters are among the best-studied exoplanets, but it is still poorly understood how their chemical composition and cloud properties vary with longitude. Theoretical models predict that clouds may condense on nightside molecular abundances can be driven out of equilibrium by zonal winds. Here we report a phase-resolved emission spectrum hot Jupiter WASP-43b measured from 5 μm to 12 JWST’s Mid-Infrared Instrument. The spectra reveal large day–night temperature contrast (with...
Observations of transiting gas giant exoplanets have revealed a pervasive depletion methane, which has only recently been identified atmospherically. The is thought to be maintained by disequilibrium processes such as photochemistry or mixing from hotter interior. However, the interiors are largely unconstrained along with vertical strength and upper limits on CH$_4$ available. warm Neptune WASP-107 b stands out among an unusually low density, reported core mass, temperatures amenable though...
ABSTRACT GJ 1214b is the most studied sub-Neptune exoplanet to date. Recent measurements have shown its near-infrared transmission spectrum be flat, pointing a high-altitude opacity source in exoplanet's atmosphere, either equilibrium condensate clouds or photochemical hazes. Many photometric observations been reported optical by different groups, though simultaneous spanning entire regime are lacking. We present an (4500–9260 Å) of 14 bins, measured with Magellan /IMACS repeatedly over...
We report the detection of a transiting Earth-size planet around GJ 357, nearby M2.5 V star, using data from Transiting Exoplanet Survey Satellite (TESS). 357 b (TOI-562.01) is transiting, hot, Earth-sized ( T eq = 525 ± 11 K) with radius R 1.217 0.084 ⊕ and an orbital period P 3.93 d. Precise stellar radial velocities CARMENES PFS, as well archival HIRES, UVES, HARPS also display 3.93-day periodicity, confirming planetary nature leading to mass M 1.84 0.31 . In addition velocity signal for...
The short period ($0.94$-day) transiting exoplanet WASP-19b is an exceptional target for transmission spectroscopy studies, due to its relatively large atmospheric scale-height ($\sim 500$ km) and equilibrium temperature 2100$ K). Here we report on six precise spectroscopic Magellan/IMACS observations, five of which the full optical window from $0.45-0.9μ$m one targeting $0.4-0.55μ$m blue-optical range. Five these datasets are consistent with a spectrum without any significant spectral...
The James Webb Space Telescope (JWST) presents the opportunity to transform our understanding of planets and origins life by revealing atmospheric compositions, structures, dynamics transiting exoplanets in unprecedented detail. However, high-precision, timeseries observations required for such investigations have unique technical challenges, prior experience with Hubble, Spitzer, other facilities indicates that there will be a steep learning curve when JWST becomes operational. In this...
Very precise measurements of exoplanet transit light curves both from ground- and space-based observatories make it now possible to fit the limb-darkening coefficients in transit-fitting procedure rather than fix them theoretical values. This strategy has been shown give better results, as fixing values can rise important systematic errors which directly impact physical properties system derived such planetary radius. However, studies effect assumptions on retrieved parameters have mostly...
Wide field surveys for transiting planets are well suited to searching diverse stellar populations, enabling a better understanding of the link between properties and their parent stars. We report discovery HAT-P-69b (TOI 625.01) HAT-P-70b 624.01), two new hot Jupiters around A stars from HATNet survey which have also been observed by Transiting Exoplanet Survey Satellite (TESS). has mass 3.58 +0.58/-0.58 MJup radius 1.676 +0.051/-0.033 RJup, residing in prograde 4.79-day orbit. 1.87...
We present the discovery of TOI-197.01, first transiting planet identified by Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology host star is possible. TOI-197 (HIP116158) a bright (V=8.2 mag), spectroscopically classified subgiant oscillates with an average frequency about 430 muHz and displays clear signature mixed modes. The oscillation amplitude confirms that redder TESS bandpass compared to Kepler has small effect on oscillations, supporting expected yield thousands...
We present the Collection of Elemental Routines for Echelle Spectra (CERES). These routines were developed construction automated pipelines reduction, extraction and analysis spectra acquired with different instruments, allowing obtention homogeneous standardised results. This modular code includes tools handling steps processing: CCD image reductions, identification tracing echelle orders, optimal rectangular extraction, computation wavelength solution, estimation radial velocities, rough...
Abstract Although the main goal of Transiting Exoplanet Survey Satellite (TESS) is to search for new transiting exoplanets, its data can also be used study already-known systems in further detail. The TESS bandpass particularly interesting limb-darkening effect stellar host that imprinted transit light curves, as widely phoenix and atlas models predict different profiles. Here we this by fitting curves 176 known exoplanetary observed TESS, which allows us extract empirical coefficients...
The CARMENES instrument was conceived to deliver high-accuracy radial velocity (RV) measurements with long-term stability search for temperate rocky planets around a sample of nearby cool stars. broad wavelength coverage designed provide range stellar activity indicators assess the nature potential RV signals and valuable spectral information help characterise targets. Data Release 1 (DR1) makes public all observations obtained during guaranteed time observations, which ran from 2016 2020...