We provide here tables of stellar limb-darkening coefficients (LDCs) for the Ariel ESA M4 space mission. These tables include LDCs corresponding to different wavelength bins and white bands for the ...NIRSpec, AIRS-Ch0 and AIRS-Ch1 spectrographs, and those corresponding to the VISPhot, FGS1 and FGS2 photometers. The LDCs are calculated with the open-source software ExoTETHyS for three complete grids of stellar atmosphere models obtained with the ATLAS9 and PHOENIX codes. The three model grids are complementary, as the PHOENIX code adopts more modern input physics and spherical geometry, while the models calculated with ATLAS9 cover wider ranges of stellar parameters. The LDCs obtained from corresponding models in the ATLAS9 and PHOENIX grids are compared in the main text. All together the models cover the following ranges in effective temperature (1500
K
≤
T
eff
≤ 50000
K
), surface gravity (0.0 dex
≤
log
g
≤
6.0
dex), and metallicity (− 5.0 ≤
M
/
H
≤ 1.0).
The goal of the Ariel space mission is to observe a large and diversified population of transiting planets around a range of host star types to collect information on their atmospheric composition. ...The planetary bulk and atmospheric compositions bear the marks of the way the planets formed: Ariel’s observations will therefore provide an unprecedented wealth of data to advance our understanding of planet formation in our Galaxy. A number of environmental and evolutionary factors, however, can affect the final atmospheric composition. Here we provide a concise overview of which factors and effects of the star and planet formation processes can shape the atmospheric compositions that will be observed by Ariel, and highlight how Ariel’s characteristics make this mission optimally suited to address this very complex problem.
Ariel has been selected as the next ESA M4 science mission and it is expected to be launched in 2028. During its 4-year mission, Ariel will observe the atmospheres of a large and diversified ...population of transiting exoplanets. A key factor for the achievement of the scientific goal of Ariel is the selection strategy for the definition of the input target list. A meaningful choice of the targets requires an accurate knowledge of the planet hosting star properties and this is necessary to be obtained well before the launch. In this work, we present the results of a bench-marking analysis between three different spectroscopic techniques used to determine stellar parameters for a selected number of targets belonging to the Ariel reference sample. We aim to consolidate a method that will be used to homogeneously determine the stellar parameters of the complete Ariel reference sample. Homogeneous, accurate and precise derivation of stellar parameters is crucial for characterising exoplanet-host stars and in turn is a key factor for the accuracy of the planet properties.
The Ariel mission will characterise the chemical and thermal properties of the atmospheres of about a thousand exoplanets transiting their host star(s). The observation of such a large sample of ...planets will allow to deepen our understanding of planetary and atmospheric formation at the early stages, providing a truly representative picture of the chemical nature of exoplanets, and relating this directly to the type and chemical environment of the host star. Hence, the accurate and precise determination of the host star fundamental properties is essential to Ariel for drawing a comprehensive picture of the underlying essence of these planetary systems. We present here a structured approach for the characterisation of Ariel stars that accounts for the concepts of homogeneity and coherence among a large set of stellar parameters. We present here the studies and benchmark analyses we have been performing to determine robust stellar fundamental parameters, elemental abundances, activity indices, and stellar ages. In particular, we present results for the homogeneous estimation of the activity indices
S
and
log
(
R
HK
′
)
, and preliminary results for elemental abundances of Na, Al, Mg, Si, C, N. In addition, we analyse the variation of a planetary spectrum, obtained with Ariel, as a function of the uncertainty on the stellar effective temperature. Finally, we present our observational campaign for precisely and homogeneously characterising all Ariel stars in order to perform a meaningful choice of final targets before the mission launch.
The quest for Magrathea planets Ledda, Sebastiano; Danielski, Camilla; Turrini, Diego
Astronomy and astrophysics (Berlin),
07/2023, Letnik:
675
Journal Article
Recenzirano
Odprti dostop
Context.
The formation of planets around binary stars is the subject of ongoing investigations focusing on the early stages of stellar life. The evolution of binaries that become double white dwarfs ...(DWDs), however, can cause the ejection of high amounts of dust and gas. This material can give rise to circumbinary discs and become the cradle of new planets, yet no studies to date have focused on the formation of circumbinary planets around DWDs. These binaries will be the main sources of gravitational waves (GWs) detectable by the Laser Interferometer Space Antenna (LISA) mission from the European Space Agency (ESA), opening the possibility to detect circumbinary planets around short-period DWDs everywhere in the Milky Way and in the Large Magellanic Cloud via the modulation of their GW signal.
Aims.
We investigated the formation process and characteristics (e.g. formation times, masses, and final locations) of Magrathea planets within circumbinary discs around detached DWDs, paying particular attention to the formation of gas giant (GG) planets.
Methods.
We simulated multiple planet formation tracks to explore how the planetary formation processes typical of pre-main sequence (pre-MS) discs are affected by the disc environments surrounding DWDs. We investigate the mass and orbital evolution of planetary seeds growing first through pebble accretion, then by gas accretion. Our growth tracks account for both the disc accretion rate onto the central binary and the disc photoevaporation rate caused by stellar irradiation.
Results.
We present both planetary formation tracks taking place in steady-state discs, and formation tracks taking place in discs evolving as a function of time. Our simulations show that planetary formation should be common in circumbinary discs around DWDs, but the formation of GG planets can be hindered by the temperatures of the disc and the rapid disc depletion.
Conclusions.
Our results show that planetary formation in circumbinary discs around DWDs can be possible. In particular, the extreme planetary formation environment implies three significant results: (i) the accretion rate and the metallicity of the disc should be high in order to form sub-stellar objects with masses up to ~31
M
J
, this is achieved only if planet formation starts soon after the onset of the disc and if first-generation seeds are present in the disc; (ii) seeds formed within 0.1 Myr, or within 1 Myr, of the onset of the disc can only produce sub-Neptunian (SN) planets and Neptunian (N) planets, unless the disc accommodates first-generation seeds with mass 10
M
⊕
; (iii) most of the planets are finally located within 1 au of the disc centre, while they are still undergoing the gas accretion phase.
We present here a reanalysis of the Spitzer Space Telescope phase curves of the hot Jupiter WASP43 b, using the wavelet pixel-independent component analysis, a blind signal-source separation method. ...The data analyzed were recorded with the Infrared Array Camera and consisted of two visits at 3.6 m, and one visit at 4.5 m, each visit covering one transit and two eclipse events. To test the robustness of our technique we repeated the analysis on smaller portions of the phase curves, and by employing different instrument ramp models. Our reanalysis presents significant updates of the planetary parameters compared to those reported in the original phase curve study of WASP43 b. In particular, we found (1) higher nightside temperatures, (2) smaller hotspot offsets, (3) a greater consistency (∼1 ) between the two 3.6 m visits, and (4) a greater similarity with the predictions of the atmospheric circulation models. Our parameter results are consistent within 1 with those reported by a recent reanalysis of the same data sets. For each visit we studied the variation of the retrieved transit parameters as a function of various sets of stellar limb-darkening coefficients, finding significant degeneracy between the limb-darkening models and the analysis output. Furthermore, we performed the analysis of the single transit and eclipse events, and we examined the differences between these results with the ones obtained with the whole phase curve. Finally we provide a formula useful to optimize the trade-off between precision and duration of observations of transiting exoplanets.
To report and evaluate the risk factors for complications following bi-oblique proximal ulnar osteotomy (PUO) in dogs.
82 client-owned dogs (93 limbs).
Clinical records of dogs treated with ...bi-oblique PUO over a 5-year period were reviewed. Postoperative radiographs were analyzed, and osteotomy location and angles were recorded; follow-up radiographs were reviewed to assess the degree of osteotomy healing. Complications were classified as minor, major, and catastrophic. Logistic regression analysis was performed to investigate possible associations between the predictor variables and occurrence of complications.
82 dogs (93 limbs) were included. Postoperative complications were documented in 39 limbs (13 major and 26 minor). The most common major complication was osteotomy nonunion (8 limbs), while the most common minor complication was delayed union (21 limbs). Statistical analysis revealed that lower body weight (P = .01) and older age (P = .04) were significantly associated with the development of postoperative complications.
In this study, lighter and older dogs were more likely to develop complications following bi-oblique proximal ulnar osteotomy. We did not identify an association between osteotomy angle and location on complication rate. Careful patient selection is therefore required to reduce the incidence of postoperative complications after bi-oblique PUO.
ABSTRACT
The Laser Interferometer Space Antenna (LISA) will detect and characterize ∼104 Galactic Binaries, consisting predominantly of two white dwarfs (WDs). An interesting prospect within this ...population is a third object – another WD star, a circumbinary exoplanet (CBP), or a brown dwarf (BD) – in orbit about the inner WD pair. We present the first fully Bayesian detection and posterior analysis of substellar objects with LISA, focusing on the characterization of CBPs. We used an optimistic astrophysically motivated catalogue of these CBP third-body sources, including their orbital eccentricity around the inner binary for the first time. We examined Bayesian evidence computations for detectability, as well as the effects on the posterior distributions for both the inner binary parameters and the third-body parameters. We find that the posterior behaviour bifurcates based on whether the third-body period is above or below half the observation time. Additionally, we find that undetectable third-body sources can bias the inner binary parameters whether or not the correct template is used. We used the information retrieved from the study of the CBP population to make an initial conservative prediction for the number of detectable BD systems in the original catalogue. We end with commentary on the predicted qualitative effects on LISA global fitting and Galactic Binary population analysis. The procedure used in this work is generic and can be directly applied to other astrophysical effects expected within the Galactic Binary population.
The Mid-Infrared instrument (MIRI) on board the James Webb Space Telescope will perform the first ever characterization of young giant exoplanets observed by direct imaging in the 5-28 m spectral ...range. This wavelength range is key for both determining the bolometric luminosity of the cool known exoplanets and for accessing the strongest ammonia bands. In conjunction with shorter wavelength observations, MIRI will enable a more accurate characterization of the exoplanetary atmospheric properties. Here we consider a subsample of the currently known exoplanets detected by direct imaging, and we discuss their detectability with MIRI, either using the coronagraphic or the spectroscopic modes. By using the Exo-REM atmosphere model, we calculate the mid-infrared emission spectra of 14 exoplanets, and we simulate MIRI coronagraphic or spectroscopic observations. Specifically, we analyze four coronagraphic observational setups, which depend on (i) the target-star and reference-star offset (0, 3, 14 mas), (ii) the wavefront-error (130, 204 nm root mean square), and (iii) the telescope jitter amplitude (1.6, 7 mas). We then determine the signal-to-noise and integration time values for the coronagraphic targets whose planet-to-star contrasts range from 3.9 to 10.1 mag. We conclude that all the MIRI targets should be observable with different degrees of difficulty, which depends on the final in-flight instrument performances. Furthermore, we test for detection of ammonia in the atmosphere of the coolest targets. Finally, we present the case of HR 8799 b to discuss what MIRI observations can bring to the knowledge of a planetary atmosphere, either alone or in combination with shorter wavelength observations.
Context. β
Pictoris is a young nearby system hosting a well-resolved edge-on debris disk, along with at least two exoplanets. It offers key opportunities for carrying out detailed studies of the ...evolution of young planetary systems and their shaping soon after the end of the planetary formation phase.
Aims.
We analyzed high-contrast coronagraphic images of this system, obtained in the mid-infrared, taking advantage of the NEAR experiment using the VLT/VISIR instrument, which provides access to adaptive optics, as well as phase coronagraphy. The goal of our analysis is to investigate both the detection of the planet
β
Pictoris b and of the disk features at mid-IR wavelengths. In addition, by combining several epochs of observation, we expect to constrain the position of the known clumps and improve our knowledge on the dynamics of the disk.
Methods.
We observed the
β
Pictoris system over two nights in December 2019 in the 10–12.5 µm coronagraphic filter. To evaluate the planet b flux contribution, we extracted the photometry at the expected position of the planet and compared it to the flux published in the literature. In addition, we used previous data from T-ReCS and VISIR in the mid-IR, updating the star's distance, to study the evolution of the position of the southwest clump that was initially observed in the planetary disk back in 2003.
Results.
While we did not detect the planet b, we were able to put constraints on the presence of circumplanetary material, ruling out the equivalent of a Saturn-like planetary ring around the planet. The disk presents several noticeable structures, including the known southwest clump. Using a 16-yr baseline, sampled with five epochs of observations, we were able to examine the evolution of the clump. We found that the clump orbits in a Keplerian motion with a semi-major axis of 56.1
−0.3
+0.4
au. In addition to the known clump, the images clearly show the presence of a second clump on the northeast side of the disk as well as possibly fainter and closer structures that are yet to be confirmed. Furthermore, we found correlations between the CO clumps detected with ALMA and the northeastern and southwestern clumps in the mid-IR images.
Conclusions.
If the circumplanetary material were located at the Roche radius, the maximum amount of dust determined from the flux upper limit around
β
Pictoris b would correspond to the mass of an asteroid of 5 km in diameter. Finally, the Keplerian motion of the southwestern clump is possibly indicative of a yet-to-be detected planet or signals the presence of a vortex.
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