SPICES (Spectro-Polarimetric Imaging and Characterization of Exoplanetary Systems) is a five-year M-class mission proposed to ESA Cosmic Vision. Its purpose is to image and characterize long-period ...extrasolar planets and circumstellar disks in the visible (450–900 nm) at a spectral resolution of about 40 using both spectroscopy and polarimetry. By 2020/2022, present and near-term instruments will have found several tens of planets that SPICES will be able to observe and study in detail. Equipped with a 1.5 m telescope, SPICES can preferentially access exoplanets located at several AUs (0.5–10 AU) from nearby stars (<25 pc) with masses ranging from a few Jupiter masses to Super Earths (∼2 Earth radii, ∼10 M
⊕
) as well as circumstellar disks as faint as a few times the zodiacal light in the Solar System.
We observed a full-orbit phase curve of the hot Jupiter WASP-43b with MIRI/LRS as part of the Transiting Exoplanet Community Early Release Science Program. Here we report preliminary findings for the ...instrument performance from the team's MIRI Working Group. Overall we find that MIRI's performance for phase curve observations is excellent, with a few minor caveats. The key takeaways for Cycle 2 planning with MIRI/LRS are: (1) long-duration observations (> 24 hours) have now been successfully executed; (2) for phase curves, we recommend including a one-hour burn-in period prior to taking science data to mitigate the effects of the ramp systematic; and (3) we do not yet recommend partial phase curve observations. In addition, we also find that: the position of the spectrum on the detector is stable to within 0.03 pixels over the full 26.5-hour observation; the light curves typically show a systematic downward ramp that is strongest for the first 30 minutes, but continues to decay for hours; from 10.6-11.8 microns, the ramp effect has remarkably different behavior, possibly due to a different illumination history for the affected region of the detector; after trimming the integrations most affected by the initial ramps and correcting the remaining systematics with analytic models, we obtain residuals to the light-curve fits that are typically within 25% of the photon noise limit for 0.5-micron spectroscopic bins; non-linearity correction is not a significant source of additional noise for WASP-43, though it may be an issue for brighter targets; the gain value of 5.5 electrons/DN currently on CRDS and JDox is known to be incorrect, and the current best estimate for the gain is approximately 3.1 electrons/DN; new reference files for the JWST calibration pipeline reflecting these findings are under development at STScI.
Abstract
We present the ultraviolet luminosity function and an estimate of the cosmic star formation rate density at 8 <
z
< 13 derived from deep NIRCam observations taken in parallel with the MIRI ...Deep Survey of the Hubble Ultra Deep Field (HUDF), NIRCam covering the parallel field 2. Our deep (40 hr) NIRCam observations reach an F277W magnitude of 30.8 (5
σ
), more than 2 mag deeper than JWST public data sets already analyzed to find high-redshift galaxies. We select a sample of 44
z
> 8 galaxy candidates based on their dropout nature in the F115W and/or F150W filters, a high probability for their photometric redshifts, estimated with three different codes, being at
z
> 8, good fits based on
χ
2
calculations, and predominant solutions compared to
z
< 8 alternatives. We find mild evolution in the luminosity function from
z
∼ 13 to
z
∼ 8, i.e., only a small increase in the average number density of ∼0.2 dex, while the faint-end slope and absolute magnitude of the knee remain approximately constant, with values
α
= − 2.2 ± 0.1, and
M
*
= − 20.8 ± 0.2 mag. Comparing our results with the predictions of state-of-the-art galaxy evolution models, we find two main results: (1) a slower increase with time in the cosmic star formation rate density compared to a steeper rise predicted by models; (2) nearly a factor of 10 higher star formation activity concentrated in scales around 2 kpc in galaxies with stellar masses ∼10
8
M
⊙
during the first 350 Myr of the universe,
z
∼ 12, with models matching better the luminosity density observational estimations ∼150 Myr later, by
z
∼ 9.
We investigate the properties of strong (Hb+OIII) emitters before and after the end of the Epoch of Reionization from z=8 to z=5.5. We make use of ultra-deep JWST/NIRCam imaging in the Parallel Field ...of the MIRI Deep Imaging Survey (MIDIS) in the Hubble eXtreme Deep Field (P2-XDF), in order to select prominent (Hb+OIII) emitters (with rest EW_0 > 100 Angstroms) at z=5.5-7, based on their flux density enhancement in the F356W band with respect to the spectral energy distribution continuum. We complement our selection with other (Hb+OIII) emitters from the literature at similar and higher (z=7-8) redshifts. We find (non-independent) anti-correlations between EW_0(Hb+OIII) and both galaxy stellar mass and age, in agreement with previous studies, and a positive correlation with specific star formation rate (sSFR). On the SFR-M* plane, the (Hb+OIII) emitters populate both the star-formation main sequence and the starburst region, which become indistinguishable at low stellar masses (log10(M*) < 7.5). We find tentative evidence for a non-monotonic relation between EW_0(Hb+OIII) and SFR, such that both parameters correlate with each other at SFR > 1 Msun/yr, while the correlation flattens out at lower SFRs. This suggests that low metallicities producing high EW_0(Hb+OIII) could be important at low SFR values. Interestingly, the properties of the strong emitters and other galaxies (33% and 67% of our z=5.5-7 sample, respectively) are similar, including, in many cases, high sSFR. Therefore, it is crucial to consider both emitters and non-emitters to obtain a complete picture of the cosmic star formation activity around the Epoch of Reionization.
Interactions between exoplanetary atmospheres and internal properties have long been hypothesized to be drivers of the inflation mechanisms of gaseous planets and apparent atmospheric chemical ...disequilibrium conditions. However, transmission spectra of exoplanets has been limited in its ability to observational confirm these theories due to the limited wavelength coverage of HST and inferences of single molecules, mostly H\(_2\)O. In this work, we present the panchromatic transmission spectrum of the approximately 750 K, low-density, Neptune-sized exoplanet WASP-107b using a combination of HST WFC3, JWST NIRCam and MIRI. From this spectrum, we detect spectroscopic features due to H\(_2\)O (21\(\sigma\)), CH\(_4\) (5\(\sigma\)), CO (7\(\sigma\)), CO\(_2\) (29\(\sigma\)), SO\(_2\) (9\(\sigma\)), and NH\(_3\) (6\(\sigma\)). The presence of these molecules enable constraints on the atmospheric metal enrichment (M/H is 10--18\(\times\) Solar), vertical mixing strength (log\(_{10}\)K\(_{zz}\)=8.4--9.0 cm\(^2\)s\(^{-1}\)), and internal temperature (\(>\)345 K). The high internal temperature is suggestive of tidally-driven inflation acting upon a Neptune-like internal structure, which can naturally explain the planet's large radius and low density. These findings suggest that eccentricity driven tidal heating is a critical process governing atmospheric chemistry and interior structure inferences for a majority of the cool (\(<\)1,000K) super-Earth-to-Saturn mass exoplanet population.
Abstract
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.
Most stars form in multiple systems whose properties can significantly impact circumstellar disk evolution. We investigate the physical and chemical properties of the equal-mass, small separation ...(~66 mas, ~9 au) DF Tau binary system. Previous observations indicated that only DF Tau A has a circumstellar disk. We present JWST-MIRI MRS observations of DF Tau. The MIRI spectrum shows a forest of H2O lines and emission from CO, C2H2, HCN, CO2, and OH. LTE slab models are used to determine the properties of the gas, and we analyze high angular spatial and spectral resolution data from ALMA, VLTI-GRAVITY, and IRTF-iSHELL to aid in the interpretation of the JWST data. The 1.3 mm ALMA continuum data show two equal-brightness sources of compact (R<3 au) emission, with separations and movement consistent with astrometry from VLTI-GRAVITY and the known orbit. This is interpreted as a robust detection of a disk around DF Tau B, which we suggest may host a small (~1 au) cavity to reconcile all observations. The disk around DF Tau A is expected to be a full disk, and spatially and spectrally resolved dust and gas emission points to hot, close-in (<0.2 au) material. Hot (~500-1000 K) H2O, HCN, and C2H2 emission in the MIRI data likely originate in the DF Tau A disk, while a cold (<200 K) H2O component with an extended emitting area is consistent with an origin from both disks. Despite the very compact outer disks, the inner disk composition and conditions are similar to isolated systems, suggesting that the close binary nature is not a driving factor in setting the inner disk chemistry. However, constraining the geometry of the disks, for instance, via higher resolution ALMA observations, would provide additional insight into the mid-infrared gas emission. JWST observations of spatially resolved binaries will be important for understanding the impact of binarity on inner disk chemistry more generally.
We present eclipse maps of the two-dimensional thermal emission from the dayside of the hot Jupiter WASP-43b, derived from an observation of a phase curve with the JWST MIRI/LRS instrument. The ...observed eclipse shapes deviate significantly from those expected for a planet emitting uniformly over its surface. We fit a map to this deviation, constructed from spherical harmonics up to order \(\ell_{\rm max}=2\), alongside the planetary, orbital, stellar, and systematic parameters. This yields a map with a meridionally-averaged eastward hot-spot shift of \((7.75 \pm 0.36)^{\circ}\), with no significant degeneracy between the map and the additional parameters. We show the latitudinal and longitudinal contributions of the day-side emission structure to the eclipse shape, finding a latitudinal signal of \(\sim\)200 ppm and a longitudinal signal of \(\sim\)250 ppm. To investigate the sensitivity of the map to the method, we fix the non-mapping parameters and derive an "eigenmap" fitted with an optimised number of orthogonal phase curves, which yields a similar map to the \(\ell_{\rm max}=2\) map. We also fit a map up to \(\ell_{\rm max}=3\), which shows a smaller hot-spot shift, with a larger uncertainty. These maps are similar to those produced by atmospheric simulations. We conclude that there is a significant mapping signal which constrains the spherical harmonic components of our model up to \(\ell_{\rm max}=2\). Alternative mapping models may derive different structures with smaller-scale features; we suggest that further observations of WASP-43b and other planets will drive the development of more robust methods and more accurate maps.
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