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result(s) for
"Samland, Matthias"
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A wide-orbit giant planet in the high-mass b Centauri binary system
by
Bonnefoy, Mickaël
,
Henning, Thomas
,
Viswanath, Gayathri
in
639/33/34/862
,
639/33/34/867
,
Binary stars
2021
Planet formation occurs around a wide range of stellar masses and stellar system architectures
1
. An improved understanding of the formation process can be achieved by studying it across the full parameter space, particularly towards the extremes. Earlier studies of planets in close-in orbits around high-mass stars have revealed an increase in giant planet frequency with increasing stellar mass
2
until a turnover point at 1.9 solar masses (
M
⊙
), above which the frequency rapidly decreases
3
. This could potentially imply that planet formation is impeded around more massive stars, and that giant planets around stars exceeding 3
M
⊙
may be rare or non-existent. However, the methods used to detect planets in small orbits are insensitive to planets in wide orbits. Here we demonstrate the existence of a planet at 560 times the Sun–Earth distance from the 6- to 10-
M
⊙
binary b Centauri through direct imaging. The planet-to-star mass ratio of 0.10–0.17% is similar to the Jupiter–Sun ratio, but the separation of the detected planet is about 100 times wider than that of Jupiter. Our results show that planets can reside in much more massive stellar systems than what would be expected from extrapolation of previous results. The planet is unlikely to have formed in situ through the conventional core accretion mechanism
4
, but might have formed elsewhere and arrived to its present location through dynamical interactions, or might have formed via gravitational instability.
A direct imaging study demonstrates the existence of a giant planet in a wide orbit around the high-mass b Centauri binary system, and uses measurements of the orbital properties to discuss its formation mechanism.
Journal Article
Water in the terrestrial planet-forming zone of the PDS 70 disk
2023
Terrestrial and sub-Neptune planets are expected to form in the inner (less than 10
au
) regions of protoplanetary disks
1
. Water plays a key role in their formation
2
–
4
, although it is yet unclear whether water molecules are formed in situ or transported from the outer disk
5
,
6
. So far Spitzer Space Telescope observations have only provided water luminosity upper limits for dust-depleted inner disks
7
, similar to PDS 70, the first system with direct confirmation of protoplanet presence
8
,
9
. Here we report JWST observations of PDS 70, a benchmark target to search for water in a disk hosting a large (approximately 54
au
) planet-carved gap separating an inner and outer disk
10
,
11
. Our findings show water in the inner disk of PDS 70. This implies that potential terrestrial planets forming therein have access to a water reservoir. The column densities of water vapour suggest in-situ formation via a reaction sequence involving O, H
2
and/or OH, and survival through water self-shielding
5
. This is also supported by the presence of CO
2
emission, another molecule sensitive to ultraviolet photodissociation. Dust shielding, and replenishment of both gas and small dust from the outer disk, may also play a role in sustaining the water reservoir
12
. Our observations also reveal a strong variability of the mid-infrared spectral energy distribution, pointing to a change of inner disk geometry.
Observations with the sensitive mid-infrared spectrometer MIRI on board JWST reveal the presence of a water vapour reservoir in the terrestrial plant-forming zone of the young planetary system PDS 70.
Journal Article
A rich hydrocarbon chemistry and high C to O ratio in the inner disk around a very low-mass star
2023
Carbon is an essential element for life but how much can be delivered to young planets is still an open question. The chemical characterization of planet-forming disks is a crucial step in our understanding of the diversity and habitability of exoplanets. Very low-mass stars (less than 0.2 M⊙) are interesting targets because they host a rich population of terrestrial planets. Here we present the James Webb Space Telescope detection of abundant hydrocarbons in the disk of a very low-mass star obtained as part of the Mid-InfraRed Instrument mid-INfrared Disk Survey (MINDS). In addition to very strong and broad emission from C2H2 and its 13C12CH2 isotopologue, C4H2, benzene and possibly CH4 are identified, but water, polycyclic aromatic hydrocarbons and silicate features are weak or absent. The lack of small silicate grains indicates that we can look deep down into this disk. These detections testify to an active warm hydrocarbon chemistry with a high C/O ratio larger than unity in the inner 0.1 astronomical units (AU) of this disk, perhaps due to destruction of carbonaceous grains. The exceptionally high C2H2/CO2 and C2H2/H2O column density ratios indicate that oxygen is locked up in icy pebbles and planetesimals outside the water iceline. This, in turn, will have important consequences for the composition of forming exoplanets.Highly abundant hydrocarbons in a very low-mass star’s disk are detected using the JWST. This unique chemical composition is probably due to the destruction of carbon grains, and the resulting high gaseous C/O ratio may have a profound impact on the composition of growing exoplanets.
Journal Article
The JWST Early Release Science Program for the Direct Imaging and Spectroscopy of Exoplanetary Systems
by
Mazoyer, Johan
,
Janson, Markus
,
Quanz, Sascha P.
in
Analogs
,
Astrophysics
,
Aérospatiale, astronomie & astrophysique
2022
The direct characterization of exoplanetary systems with high-contrast imaging is among the highest priorities for the broader exoplanet community. As large space missions will be necessary for detecting and characterizing exo-Earth twins, developing the techniques and technology for direct imaging of exoplanets is a driving focus for the community. For the first time, JWST will directly observe extrasolar planets at mid-infrared wavelengths beyond 5 μ m, deliver detailed spectroscopy revealing much more precise chemical abundances and atmospheric conditions, and provide sensitivity to analogs of our solar system ice-giant planets at wide orbital separations, an entirely new class of exoplanet. However, in order to maximize the scientific output over the lifetime of the mission, an exquisite understanding of the instrumental performance of JWST is needed as early in the mission as possible. In this paper, we describe our 55 hr Early Release Science Program that will utilize all four JWST instruments to extend the characterization of planetary-mass companions to ∼15 μ m as well as image a circumstellar disk in the mid-infrared with unprecedented sensitivity. Our program will also assess the performance of the observatory in the key modes expected to be commonly used for exoplanet direct imaging and spectroscopy, optimize data calibration and processing, and generate representative data sets that will enable a broad user base to effectively plan for general observing programs in future Cycles.
Journal Article
Estimation of Contaminants for Direct Imaging of Exoplanets: Constraint on the Stellar Distribution Model with both NIR and Deep Imaging Data
by
Fukagawa, Misato
,
Yamamoto, Kodai
,
Matsuo, Taro
in
Astronomy
,
Contributed Papers
,
Extrasolar planets
2013
There are faint contaminants near primary stars in the direct imaging of exoplanets. Our goal is to estimate statistically the ratio of exoplanets in the detected batch of point sources by calculating the fraction of contamination. In this study, we compared the detected number of stars with the number of contaminants predicted by our model. We found that the observed number of faint stars were fewer than the predicted results towards the Pleiades and GOODS-South field when the parameters of the conventional stellar distribution models were employed. We thus estimated new model parameters in correspondence to the results of the observations.
Journal Article
15 NH 3 in the atmosphere of a cool brown dwarf
by
Mollière, Paul
,
Henning, Thomas
,
Mueller, Michael
in
Atmosphere
,
Exobiology - methods
,
Extraterrestrial Environment
2023
Brown dwarfs serve as ideal laboratories for studying the atmospheres of giant exoplanets on wide orbits, as the governing physical and chemical processes within them are nearly identical
. Understanding the formation of gas-giant planets is challenging, often involving the endeavour to link atmospheric abundance ratios, such as the carbon-to-oxygen (C/O) ratio, to formation scenarios
. However, the complexity of planet formation requires further tracers, as the unambiguous interpretation of the measured C/O ratio is fraught with complexity
. Isotope ratios, such as deuterium to hydrogen and
N/
N, offer a promising avenue to gain further insight into this formation process, mirroring their use within the Solar System
. For exoplanets, only a handful of constraints on
C/
C exist, pointing to the accretion of
C-rich ice from beyond the CO iceline of the disks
. Here we report on the mid-infrared detection of the
NH
and
NH
isotopologues in the atmosphere of a cool brown dwarf with an effective temperature of 380 K in a spectrum taken with the Mid-Infrared Instrument (MIRI) of JWST. As expected, our results reveal a
N/
N value consistent with star-like formation by gravitational collapse, demonstrating that this ratio can be accurately constrained. Because young stars and their planets should be more strongly enriched in the
N isotope
, we expect that
NH
will be detectable in several cold, wide-separation exoplanets.
Journal Article
15NH3 in the atmosphere of a cool brown dwarf
by
Mollière, Paul
,
Henning, Thomas
,
Mueller, Michael
in
639/33/34/862
,
639/33/34/867
,
639/33/445/862
2023
Brown dwarfs serve as ideal laboratories for studying the atmospheres of giant exoplanets on wide orbits, as the governing physical and chemical processes within them are nearly identical
1
,
2
. Understanding the formation of gas-giant planets is challenging, often involving the endeavour to link atmospheric abundance ratios, such as the carbon-to-oxygen (C/O) ratio, to formation scenarios
3
. However, the complexity of planet formation requires further tracers, as the unambiguous interpretation of the measured C/O ratio is fraught with complexity
4
. Isotope ratios, such as deuterium to hydrogen and
14
N/
15
N, offer a promising avenue to gain further insight into this formation process, mirroring their use within the Solar System
5
–
7
. For exoplanets, only a handful of constraints on
12
C/
13
C exist, pointing to the accretion of
13
C-rich ice from beyond the CO iceline of the disks
8
,
9
. Here we report on the mid-infrared detection of the
14
NH
3
and
15
NH
3
isotopologues in the atmosphere of a cool brown dwarf with an effective temperature of 380 K in a spectrum taken with the Mid-Infrared Instrument (MIRI) of JWST. As expected, our results reveal a
14
N/
15
N value consistent with star-like formation by gravitational collapse, demonstrating that this ratio can be accurately constrained. Because young stars and their planets should be more strongly enriched in the
15
N isotope
10
, we expect that
15
NH
3
will be detectable in several cold, wide-separation exoplanets.
Observations from the JWST MIRI showed the detection of
14
NH
3
and
15
NH
3
isotopologues in the atmosphere of a cool brown dwarf, along with a
14
N/
15
N value consistent with star-like formation by gravitational collapse.
Journal Article
The JWST Early Release Science Program for the Direct Imaging and Spectroscopy of Exoplanetary Systems
by
De Furio, Matthew
,
Mazoyer, Johan
,
Janson, Markus
in
Astronomical Instrumentation, Telescopes, Observatories, and Site Characterization
2022
The direct characterization of exoplanetary systems with high-contrast imaging is among the highest priorities for the broader exoplanet community. As large space missions will be necessary for detecting and characterizing exo-Earth twins, developing the techniques and technology for direct imaging of exoplanets is a driving focus for the community. For the first time, JWST will directly observe extrasolar planets at mid-infrared wavelengths beyond 5 μm, deliver detailed spectroscopy revealing much more precise chemical abundances and atmospheric conditions, and provide sensitivity to analogs of our solar system ice-giant planets at wide orbital separations, an entirely new class of exoplanet. However, in order to maximize the scientific output over the lifetime of the mission, an exquisite understanding of the instrumental performance of JWST is needed as early in the mission as possible. In this paper, we describe our 55 hr Early Release Science Program that will utilize all four JWST instruments to extend the characterization of planetary-mass companions to ∼15 μm as well as image a circumstellar disk in the mid-infrared with unprecedented sensitivity. Our program will also assess the performance of the observatory in the key modes expected to be commonly used for exoplanet direct imaging and spectroscopy, optimize data calibration and processing, and generate representative data sets that will enable a broad user base to effectively plan for general observing programs in future Cycles.
Journal Article
spherical: A Comprehensive Database and Automated Pipeline for VLT/SPHERE High-Contrast Imaging
2025
I present spherical (https://github.com/m-samland/spherical), a software package and database designed for the ESO VLT/SPHERE high-contrast imager. SPHERE has produced the world's largest archive of direct imaging observations of exoplanets and circumstellar disks, but its heterogeneous metadata and fragmented reduction tools make end-to-end analysis labor-intensive. spherical addresses this by combining (1) a curated, regularly updated, and searchable database of all SPHERE observations, cross-matched with stellar properties and observing conditions, and (2) a Python-based, script-driven pipeline for the Integral Field Spectrograph (IFS). The database, archived on Zenodo (https://doi.org/10.5281/zenodo.15147730) and reproducible from the ESO archive, currently includes about 6000 IRDIS dual-band imaging, about 1000 IRDIS polarimetric, and about 4500 IFS sequences, with additional modes (ZIMPOL, IRDIS-LSS, SAM) planned. The pipeline automates raw data retrieval, calibration, and IFS reduction with the adapted open-source CHARIS instrument pipeline, followed by astrometric and photometric calibration and post-processing with TRAP for companion detection and spectral extraction. spherical lowers the barrier from raw files to science-ready products, enabling homogeneous population studies, atmospheric characterization of companions, and efficient survey follow-up, while remaining interoperable with community tools such as VIP, pyKLIP, and IRDAP.
Spectral cube extraction for the VLT/SPHERE IFS: Open-source pipeline with full forward modeling and improved sensitivity
2022
We present a new open-source data-reduction pipeline to reconstruct spectral data cubes from raw SPHERE integral-field spectrograph (IFS) data. The pipeline is written in Python and based on the pipeline that was developed for the CHARIS IFS. It introduces several improvements to SPHERE data analysis that ultimately produce significant improvements in postprocessing sensitivity. We first used new data to measure SPHERE lenslet point spread functions (PSFs) at the four laser calibration wavelengths. These lenslet PSFs enabled us to forward-model SPHERE data, to extract spectra using a least-squares fit, and to remove spectral crosstalk using the measured lenslet PSFs. Our approach also reduces the number of required interpolations, both spectral and spatial, and can preserve the original hexagonal lenslet geometry in the SPHERE IFS. In the case of least-squares extraction, no interpolation of the data is performed. We demonstrate this new pipeline on the directly imaged exoplanet 51 Eri b and on observations of the hot white dwarf companion to HD 2133. The extracted spectrum of HD 2133B matches theoretical models, demonstrating spectrophotometric calibration that is good to a few percent. Postprocessing on two 51 Eri b data sets demonstrates a median improvement in sensitivity of 80% and 30% for the 2015 and 2017 data, respectively, compared to the use of cubes reconstructed by the SPHERE Data Center. The largest improvements are seen for poorer observing conditions. The new SPHERE pipeline takes less than three minutes to produce a data cube on a modern laptop, making it practical to reprocess all SPHERE IFS data.