Observing Earth-like exoplanets orbiting within the habitable zone of Sun-like stars and studying their atmospheres in reflected starlight requires contrasts of \(\sim1\mathrm{e}{-10}\) in the ...visible. At such high contrast, starlight reflected by exozodiacal dust is expected to be a significant source of contamination. Here, we present high-fidelity simulations of coronagraphic observations of a synthetic Solar System located at a distance of 10 pc and observed with a 12 m and an 8 m circumscribed aperture diameter space telescope operating at 500 nm wavelength. We explore different techniques to subtract the exozodi and stellar speckles from the simulated images in the face-on, the 30 deg inclined, and the 60 deg inclined case and quantify the remaining systematic noise as a function of the exozodiacal dust level of the system. We find that in the face-on case, the exozodi can be subtracted down to the photon noise limit for exozodi levels up to \(\sim1000\) zodi using a simple toy model for the exozodiacal disk, whereas in the 60 deg inclined case this only works up to \(\sim50\) zodi. We also investigate the impact of larger wavefront errors and larger system distance, finding that while the former have no significant impact, the latter has a strong (negative) impact. Ultimately, we derive a penalty factor as a function of the exozodi level and system inclination that should be considered in exoplanet yield studies as a realistic estimate for the excess systematic noise from the exozodi.
Interferometric observables are strongly correlated, yet it is common practice to ignore these correlations in the data analysis process. We develop an empirical model for the correlations present in ...Very Large Telescope Interferometer GRAVITY data and show that properly accounting for them yields fainter detection limits and increases the reliability of potential detections. We extracted the correlations of the (squared) visibility amplitudes and the closure phases directly from intermediate products of the GRAVITY data reduction pipeline and fitted our empirical models to them. Then, we performed model fitting and companion injection and recovery tests with both simulated and real GRAVITY data, which are affected by correlated noise, and compared the results when ignoring the correlations and when properly accounting for them with our empirical models. When accounting for the correlations, the faint source detection limits improve by a factor of up to \(\sim 2\) at angular separations \(> 20~\rm{mas}\). For commonly used detection criteria based on \(\chi^2\) statistics, this mostly results in claimed detections being more reliable. Ignoring the correlations present in interferometric data is a dangerous assumption which might lead to a large number of false detections. The commonly used detection criteria (e.g. in the model fitting pipeline CANDID) are only reliable when properly accounting for the correlations; furthermore, instrument teams should work on providing full covariance matrices instead of statistically independent error bars as part of the official data reduction pipelines.
Transition disks have large central cavities that have been spatially resolved during recent years. Cavities and other substructures in circumstellar disks are often interpreted as signposts to ...massive companions. We aim to search for stellar and substellar companions in the central regions of transition disks. We want to determine if these disks might be circumbinary in their nature, similar to the HD 142527 system. We observed four systems, HD 100453, HD 100546, HD 135344 B, and PDS 70, with the sparse aperture masking mode of VLT/SPHERE. We extracted the complex visibilities and bispectra from the H2 and H3 imaging data. A binary model was fit to the closure phases to search for companions and estimate detection limits. For validation, we also analyzed four archival datasets of HD 142527 and inferred the orbital elements and atmospheric parameters of its low-mass stellar companion. We have not detected any significant point sources in the four observed systems. With a contrast sensitivity of \(\approx\)0.004, we can rule out stellar companions down to \(\approx\)2 au and partially explore the substellar regime at separations \(\gtrsim\)3-5 au. The analysis of HD 142527 B revealed that its projected orbit is aligned with dust features in the extended inner disk and that the orbit could be close to coplanar with the outer disk. Atmospheric modeling confirms the low-gravity and slightly reddened spectral appearance. The bulk parameters are in agreement with dynamical constraints and evolutionary tracks. In contrast to HD 142527, we find no evidence that a close-in stellar companion is responsible for the resolved disk features of HD 100453, HD 100546, HD 135344 B, and PDS 70. Instead, the formation of giant planets or even low-mass brown dwarfs could be shaping the innermost environment (\(\lesssim\)20 au) of these circumstellar disks, as is the case with the planetary system of PDS 70.
The next generation of space-based observatories will characterize the atmospheres of low-mass, temperate exoplanets with the direct-imaging technique. This will be a major step forward in our ...understanding of exoplanet diversity and the prevalence of potentially habitable conditions beyond the Earth. We compute a list of currently known exoplanets detectable with the mid-infrared Large Interferometer For Exoplanets (LIFE) in thermal emission. We also compute the list of known exoplanets accessible to a notional design of the Habitable Worlds Observatory (HWO), observing in reflected starlight. With a pre-existing method, we processed the NASA Exoplanet Archive and computed orbital realizations for each known exoplanet. We derived their mass, radius, equilibrium temperature, and planet-star angular separation. We used the LIFEsim simulator to compute the integration time (\(t_{int}\)) required to detect each planet with LIFE. A planet is considered detectable if a broadband signal-to-noise ratio \(S/N\)=7 is achieved over the spectral range \(4-18.5\mu\)m in \(t_{int}\leq\)100 hours. We tested whether the planet is accessible to HWO in reflected starlight based on its notional inner and outer working angles, and minimum planet-to-star contrast. LIFE's reference configuration (four 2-m telescopes with 5% throughput and a nulling baseline between 10-100 m) can detect 212 known planets within 20 pc. Of these, 55 are also accessible to HWO in reflected starlight, offering a unique opportunity for synergies in atmospheric characterization. LIFE can also detect 32 known transiting exoplanets. Furthermore, 38 LIFE-detectable planets orbit in the habitable zone, of which 13 with \(M_p<5M_\oplus\) and 8 with \(5M_\oplus<M_p<10M_\oplus\). LIFE already has enough targets to perform ground-breaking analyses of low-mass, habitable-zone exoplanets, a fraction of which will also be accessible to other instruments.
Modeling observations of the archetypal debris disk around \(\beta\) Pic, obtained in 2023 January with the MIRI MRS on board JWST, reveals significant differences compared with that obtained with ...the IRS on board Spitzer. The bright 5 - 15 \(\mu\)m continuum excess modeled using a \(\sim\)600 K black body has disappeared. The previously prominent 18 and 23 \(\mu\)m crystalline forsterite emission features, arising from cold dust (\(\sim\)100 K) in the Rayleigh limit, have disappeared and been replaced by very weak features arising from the hotter 500 K dust population. Finally, the shape of the 10 \(\mu\)m silicate feature has changed, consistent with a shift in the temperature of the warm dust population from \(\sim\)300 K to \(\sim\)500 K and an increase in the crystalline fraction of the warm, silicate dust. Stellar radiation pressure may have blown both the hot and the cold crystalline dust particles observed in the Spitzer spectra out of the planetary system during the intervening 20 years between the Spitzer and JWST observations. These results indicate that the \(\beta\) Pic system has a dynamic circumstellar environment, and that periods of enhanced collisions can create large clouds of dust that sweep through the planetary system.
We present the first JWST/NIRCam observations of the directly-imaged gas
giant exoplanet $\beta$ Pic b. Observations in six filters using NIRCam's round
coronagraphic masks provide a high ...signal-to-noise detection of $\beta$ Pic b
and the archetypal debris disk around $\beta$ Pic over a wavelength range of
$\sim$1.7-5 $\mu$m. This paper focuses on the detection of $\beta$ Pic b and
other potential point sources in the NIRCam data, following a paper by
Rebollido et al. which presented the NIRCam and MIRI view of the debris disk
around $\beta$ Pic. We develop and validate approaches for obtaining accurate
photometry of planets in the presence of bright, complex circumstellar
backgrounds. By simultaneously fitting the planet's PSF and a geometric model
for the disk, we obtain planet photometry that is in good agreement with
previous measurements from the ground. The NIRCam data supports the cloudy
nature of $\beta$ Pic b's atmosphere and the discrepancy between its mass as
inferred from evolutionary models and the dynamical mass reported in the
literature. We further identify five additional localized sources in the data,
but all of them are found to be background stars or galaxies based on their
color or spatial extent. We can rule out additional planets in the disk
midplane above 1 Jupiter mass outward of 2 arcsec ($\sim$40 au) and away from
the disk midplane above 0.05 Jupiter masses outward of 4 arcsec ($\sim$80 au).
The inner giant planet $\beta$ Pic c remains undetected behind the
coronagraphic masks of NIRCam in our observations.
Observations of debris disks offer important insights into the formation and evolution of planetary systems. Though M dwarfs make up approximately 80% of nearby stars, very few M-dwarf debris disks ...have been studied in detail -- making it unclear how or if the information gleaned from studying debris disks around more massive stars extends to the more abundant M dwarf systems. We report the first scattered-light detection of the debris disk around the M4 star Fomalhaut C using JWST's Near Infrared Camera (NIRCam; 3.6\(~\mu\)m and 4.4\(~\mu\)m). This result adds to the prior sample of only four M-dwarf debris disks with detections in scattered light, and marks the latest spectral type and oldest star among them. The size and orientation of the disk in these data are generally consistent with the prior ALMA sub-mm detection. Though no companions are identified, these data provide strong constraints on their presence -- with sensitivity sufficient to recover sub-Saturn mass objects in the vicinity of the disk. This result illustrates the unique capability of JWST for uncovering elusive M-dwarf debris disks in scattered light, and lays the groundwork for deeper studies of such objects in the 2--5\(~\mu\)m regime.
We present JWST MIRI Medium Resolution Spectrograph (MRS) observations of the \(\beta\) Pictoris system. We detect an infrared excess from the central unresolved point source from 5 to 7.5 \(\mu\)m ...which is indicative of dust within the inner \(\sim\)7 au of the system. We perform PSF subtraction on the MRS data cubes and detect a spatially resolved dust population emitting at 5 \(\mu\)m. This spatially resolved hot dust population is best explained if the dust grains are in the small grain limit (2\(\pi\)a$\ll$$\lambda\(). The combination of unresolved and resolved dust at 5 \)\mu\(m could suggest that dust grains are being produced in the inner few au of the system and are then radiatively driven outwards, where the particles could accrete onto the known planets in the system \)\beta\( Pic b and c. We also report the detection of an emission line at 6.986 \)\mu\(m that we attribute to be Ar II. We find that the Ar II emission is spatially resolved with JWST and appears to be aligned with the dust disk. Through PSF subtraction techniques, we detect \)\beta\( Pic b at the 5\)\sigma\( level in our MRS data cubes and present the first mid-IR spectrum of the planet from 5 to 7 \)\mu\(m. The planet's spectrum is consistent with having absorption from water vapor between 5 and 6.5 \)\mu\(m. We perform atmosphere model grid fitting on spectra and photometry of \)\beta$ Pic b and find that the planet's atmosphere likely has a sub-stellar C/O ratio.
We present the first JWST MIRI and NIRCam observations of the prominent
debris disk around Beta Pictoris. Coronagraphic observations in 8 filters
spanning from 1.8 to 23~$\mu$m provide an ...unprecedentedly clear view of the
disk at these wavelengths. The objectives of the observing program were to
investigate the dust composition and distribution, and to investigate the
presence of planets in the system. In this paper, we focus on the disk
components, providing surface brightness measurements for all images and a
detailed investigation of the asymmetries observed. A companion paper by
Kammerer et al. will focus on the planets in this system using the same data.
We report for the first time the presence of an extended secondary disk in
thermal emission, with a curved extension bent away from the plane of the disk.
This feature, which we refer to as the ``cat's tail", seems to be connected
with the previously reported CO clump, mid-infrared asymmetry detected in the
southwest side, and the warp observed in scattered light. We present a model of
this secondary disk sporadically producing dust that broadly reproduces the
morphology, flux, and color of the cat's tail, as well as other features
observed in the disk, and suggests the secondary disk is composed largely of
porous, organic refractory dust grains.
The James Webb Space Telescope (JWST) will revolutionize the field of high-contrast imaging and enable both the direct detection of Saturn-mass planets and the characterization of substellar ...companions in the mid-infrared. While JWST will feature unprecedented sensitivity, angular resolution will be the key factor when competing with ground-based telescopes. Here, we aim to characterize the performance of several extreme angular resolution imaging techniques available with JWST in the 3-5 micron regime based on data taken during commissioning. Firstly, we introduce custom tools to simulate, reduce, and analyze NIRCam and MIRI coronagraphy data and use these tools to extract companion detection limits from on-sky NIRCam round and bar mask coronagraphy observations. Secondly, we present on-sky NIRISS aperture masking interferometry (AMI) and kernel phase imaging (KPI) observations from which we extract companion detection limits using the publicly available fouriever tool. Scaled to a total integration time of one hour and a target of the brightness of AB Dor, we find that NIRISS AMI and KPI reach contrasts of \(\sim\)7-8 mag at \(\sim\)70 mas and \(\sim\)9 mag at \(\sim\)200 mas. Beyond \(\sim\)250 mas, NIRCam coronagraphy reaches deeper contrasts of \(\sim\)13 mag at \(\sim\)500 mas and \(\sim\)15 mag at \(\sim\)2 arcsec. While the bar mask performs \(\sim\)1 mag better than the round mask at small angular separations \(\lesssim\)0.75 arcsec, it is the other way around at large angular separations \(\gtrsim\)1.5 arcsec. Moreover, the round mask gives access to the full 360 deg field-of-view which is beneficial for the search of new companions. We conclude that already during the instrument commissioning, JWST high-contrast imaging in the L- and M-bands performs close to its predicted limits.
