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Register a new userAncillary science with Ariel: Feasibility and scientific potential of young stellar object observations
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To investigate the feasibility of ancillary target observations with ESAs Ariel mission, we compiled a list of potentially interesting young stars: FUors, systems harbouring extreme debris discs and a larger sample of young stellar objects showing strong near/mid-infrared excess. These objects can be observed as additional targets in the waiting times between the scheduled exoplanet transit and occultation observations. After analyzing the schedule for Ariel an algorithm was constructed to find the optimal target to be observed in each gap. The selection was mainly based on the slew and stabilization time needed to observe the selected YSO, but it also incorporated the scientific importance of the targets and whether they have already been sufficiently measured. After acquiring an adequately large sample of simulation data, it was concluded that approximately 99.2% of the available -- at least one hour long -- gaps could be used effectively. With an average slewing and stabilization time of about 16.7 minutes between scheduled exoplanet transits and ancillary targets, this corresponds to an additional $2881 pm 56$ hours of active data gathering. When this additional time is used to observe our selected 200 ancillary targets, a typical signal-to-noise ratio of $sim$10$^4$ can be achieved along the whole spectral window covered by Ariel.
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Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESAs Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution.
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 ($1,500 , K le T_{mbox{eff}} le 50,000 , K$), surface gravity (0.0 dex $le log{g} le 6.0$ dex), and metallicity ($-5.0 le [M/H] le 1.0$).
Context. Studying gas chemistry in protoplanetary disks is key to understanding the process of planet formation. Sulfur chemistry in particular is poorly understood in interstellar environments, and the location of the main reservoirs remains unknown. Protoplanetary disks in Taurus are ideal targets for studying the evolution of the composition of planet forming systems. Aims. We aim to elucidate the chemical origin of sulfur-bearing molecular emission in protoplanetary disks, with a special focus on H$_2$S emission, and to identify candidate species that could become the main molecular sulfur reservoirs in protoplanetary systems. Methods. We used IRAM 30m observations of nine gas-rich young stellar objects (YSOs) in Taurus to perform a survey of sulfur-bearing and oxygen-bearing molecular species. In this paper we present our results for the CS 3-2 ($ u_0$ = 146.969 GHz), H$_2$CO 2$_{11}$-1$_{10}$ ($ u_0$ = 150.498 GHz), and H$_2$S 1$_{10}$-1$_{01}$ ($ u_0$ = 168,763 GHz) emission lines. Results. We detected H$_2$S emission in four sources out of the nine observed, significantly increasing the number of detections toward YSOs. We also detected H$_2$CO and CS in six out of the nine. We identify a tentative correlation between H$_2$S 1$_{10}$-1$_{01}$ and H$_2$CO 2$_{11}$-1$_{10}$ as well as a tentative correlation between H$_2$S 1$_{10}$-1$_{01}$ and H$_2$O 8$_{18}$-7$_{07}$. By assuming local thermodynamical equilibrium, we computed column densities for the sources in the sample, with N(o-H$_2$S) values ranging between $2.6times10^{12}$ cm$^{-2}$ and $1.5times10^{13}$ cm$^{-2}$.
The Maunakea Spectroscopic Explorer (MSE) is a planned 11.25-m aperture facility with a 1.5 square degree field of view that will be fully dedicated to multi-object spectroscopy. A rebirth of the 3.6m Canada-France-Hawaii Telescope on Maunakea, MSE will use 4332 fibers operating at three different resolving powers (R ~ 2500, 6000, 40000) across a wavelength range of 0.36-1.8mum, with dynamical fiber positioning that allows fibers to match the exposure times of individual objects. MSE will enable spectroscopic surveys with unprecedented scale and sensitivity by collecting millions of spectra per year down to limiting magnitudes of g ~ 20-24 mag, with a nominal velocity precision of ~100 m/s in high-resolution mode. This white paper describes science cases for stellar astrophysics and exoplanet science using MSE, including the discovery and atmospheric characterization of exoplanets and substellar objects, stellar physics with star clusters, asteroseismology of solar-like oscillators and opacity-driven pulsators, studies of stellar rotation, activity, and multiplicity, as well as the chemical characterization of AGB and extremely metal-poor stars.
We present 2MASS J11151597+1937266, a recently identified low-surface gravity L dwarf, classified as an L2$gamma$ based on Sloan Digital Sky Survey optical spectroscopy. We confirm this spectral type with near-infrared spectroscopy, which provides further evidence that 2MASS J11151597+1937266 is a low-surface gravity L dwarf. This object also shows significant excess mid-infrared flux, indicative of circumstellar material; and its strong H$alpha$ emission (EW$_{mathrm{H}alpha}=560pm82$ AA) is an indicator of enhanced magnetic activity or weak accretion. Comparison of its spectral energy distribution to model photospheres yields an effective temperature of $1724^{+184}_{-38}$ K. We also provide a revised distance estimate of $37pm6$ pc using a spectral type-luminosity relationship for low-surface gravity objects. The 3-dimensional galactic velocities and positions of 2MASS J11151597+1937266 do not match any known young association or moving group. Assuming a probable age in the range of 5-45 Myr, the model-dependent estimated mass of this object is between 7-21 $M_mathrm{Jup}$, making it a potentially isolated planetary-mass object. We also identify a candidate co-moving, young stellar companion, 2MASS J11131089+2110086.
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