A Reanalysis of the Fundamental Parameters and Age of TRAPPIST-1*

Gonzales, Eileen C.; Faherty, Jacqueline K.; Gagné, Jonathan; Teske, Johanna; McWilliams, Andrew; Cruz, Kelle L.

doi:10.3847/1538-4357/ab48fc

Cited by 32 publications

(50 citation statements)

References 127 publications

(157 reference statements)

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“…The differences between the two classifications is thought to be around 0.5 dex in log(g) (see Figure 9 of Burrows et al 1997), so a simple calculation shows that a radius increase of 10× would be needed to achieve the effect. Gonzales et al (2019) has further noted that the late-M dwarf TRAPPIST-1, though presumably of field age, nonetheless has near-infrared spectral indices indicating an intermediate gravity. If this star's radius is truly inflated, it could be due to magnetic activity or to tidal interactions by the numerous planets in its solar system.…”

Section: Low-gravity (Young) Objectsmentioning

confidence: 99%

The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs

Kirkpatrick

Gelino

Faherty

et al. 2021

ApJS

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We present final Spitzer trigonometric parallaxes for 361 L, T, and Y dwarfs. We combine these with prior studies to build a list of 525 known L, T, and Y dwarfs within 20 pc of the Sun, 38 of which are presented here for the first time. Using published photometry and spectroscopy as well as our own follow-up, we present an array of colormagnitude and color-color diagrams to further characterize census members, and we provide polynomial fits to the bulk trends. Using these characterizations, we assign each object a T eff value and judge sample completeness over bins of T eff and spectral type. Except for types T8 and T eff < 600 K, our census is statistically complete to the 20 pc limit. We compare our measured space densities to simulated density distributions and find that the best fit is a power law ( µ a -dN dM M ) with α = 0.6 ± 0.1. We find that the evolutionary models of Saumon & Marley correctly predict the observed magnitude of the space density spike seen at 1200 K < T eff < 1350 K, believed to be caused by an increase in the cooling timescale across the L/T transition. Defining the low-mass terminus using this sample requires a more statistically robust and complete sample of dwarfs Y0.5 and with T eff < 400 K. We

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Section: Low-gravity (Young) Objectsmentioning

confidence: 99%

The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs

Kirkpatrick

Gelino

Faherty

et al. 2021

ApJS

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125

200

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“…We note that prior to this paper different stellar parameters for TRAPPIST-1 were published. In 2019, Gonzales et al (2019) presented a distance-calibrated SED of TRAPPIST-1 using a new NIR FIRE spectrum and parallax from the Gaia DR2 data release from which they derived updated fundamental parameters for the star. Back in 2018, Van Grootel et al (2018) derived stellar parameters from two distinct approaches to compute the mass of the star, first via stellar evolution modeling, and second through an empirical derivation from dynamical masses of equivalently classified ultracool dwarfs in astrometric binaries.…”

Section: Global Analysesmentioning

confidence: 99%

“…(1) Derived for age range 0.5 to 10 Gyr, the field age constraint from Filippazzo et al (2015), see Gonzales et al (2019). Table 7.…”

Section: Global Analysesmentioning

confidence: 99%

“…First, the host star is an old M8V type star (7.6 ± 2.2 Gyr, Burgasser & Mamajek 2017) with a moderate flaring activity (about 1 or 2 flares per week, Gillon et al 2017a) and its (putative) stellar rotation period derived from K2 observations by Luger et al (2017a) is 3.30 ± 0.14 days. Recent study by Gonzales et al (2019) presented a distance-calibrated SED for the star and found, from band-by-band comparisons, that TRAPPIST-1 exhibits a blend of field star and young star spectral features. Its XUV luminosity is similar to the Sun's, which, when considering its past evolution -notably its ∼2 Gyr-long premain sequence phase (Van Grootel et al 2018) and the small orbital distances of the planets (between 0.01 and 0.06 au) -potentially drove extreme atmospheric erosion and water loss (Wheatley et al 2016;Bolmont et al 2016;Bourrier et al 2017;Fleming et al 2020).…”

Section: Introductionmentioning

confidence: 99%

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TRAPPIST-1: Global results of theSpitzerExploration Science Program Red Worlds

Ducrot

Gillon

Delrez

et al. 2020

A&A

113

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Context. With more than 1000 h of observation from Feb. 2016 to Oct. 2019, the Spitzer Exploration Program Red Worlds (ID: 13067, 13175 and 14223) exclusively targeted TRAPPIST-1, a nearby (12 pc) ultracool dwarf star, finding that it is orbited by seven transiting Earth-sized planets. At least three of these planets orbit within the classical habitable zone of the star, and all of them are well-suited for a detailed atmospheric characterization with the upcoming JWST. Aims. The main goals of the Spitzer Red Worlds program were (1) to explore the system for new transiting planets, (2) to intensively monitor the planets’ transits to yield the strongest possible constraints on their masses, sizes, compositions, and dynamics, and (3) to assess the infrared variability of the host star. In this paper, we present the global results of the project. Methods. We analyzed 88 new transits and combined them with 100 previously analyzed transits, for a total of 188 transits observed at 3.6 or 4.5 μm. For a comprehensive study, we analyzed all light curves both individually and globally. We also analyzed 29 occultations (secondary eclipses) of planet b and eight occultations of planet c observed at 4.5 μm to constrain the brightness temperatures of their daysides. Results. We identify several orphan transit-like structures in our Spitzer photometry, but all of them are of low significance. We do not confirm any new transiting planets. We do not detect any significant variation of the transit depths of the planets throughout the different campaigns. Comparing our individual and global analyses of the transits, we estimate for TRAPPIST-1 transit depth measurements mean noise floors of ~35 and 25 ppm in channels 1 and 2 of Spitzer/IRAC, respectively. We estimate that most of this noise floor is of instrumental origins and due to the large inter-pixel inhomogeneity of IRAC InSb arrays, and that the much better interpixel homogeneity of JWST instruments should result in noise floors as low as 10 ppm, which is low enough to enable the atmospheric characterization of the planets by transit transmission spectroscopy. Our analysis reveals a few outlier transits, but we cannot conclude whether or not they correspond to spot or faculae crossing events. We construct updated broadband transmission spectra for all seven planets which show consistent transit depths between the two Spitzer channels. Although we are limited by instrumental precision, the combined transmission spectrum of planet b to g tells us that their atmospheres seem unlikely to be CH4-dominated. We identify and model five distinct high energy flares in the whole dataset, and discuss our results in the context of habitability. Finally, we fail to detect occultation signals of planets b and c at 4.5 μm, and can only set 3-σ upper limits on their dayside brightness temperatures (611 K for b 586 K for c).

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“…However, we acknowledge that the density should be better constrained than either the mass or radius, because it can be computed without the stellar uncertainty . Note that the stellar radius estimate may also be biased by (i) magnetic activity effects and/or (ii) tidal interactions of the planets with the star (Burgasser and Mamajek 2017;Gonzales et al 2019) which are not included in existing stellar evolution models. Secondly, stellar contamination of the photosphere of TRAPPIST-1 by spots need to be further investigated, as it was shown to be a potential source of bias-up to ∼2.5% for TRAPPIST-1 in the infrared Spitzer IRAC bands-for the radius estimates .…”

Section: Future Prospectsmentioning

confidence: 99%

A Review of Possible Planetary Atmospheres in the TRAPPIST-1 System

et al. 2020

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TRAPPIST-1 is a fantastic nearby (∼39.14 light years) planetary system made of at least seven transiting terrestrial-size, terrestrial-mass planets all receiving a moderate amount of irradiation. To date, this is the most observationally favourable system of potentially habitable planets known to exist. Since the announcement of the discovery of the TRAPPIST-1 planetary system in 2016, a growing number of techniques and approaches have been used and proposed to characterize its true nature. Here we have compiled a state-of-the-art overview of all the observational and theoretical constraints that have been obtained so far using these techniques and approaches. The goal is to get a better understanding of whether or not TRAPPIST-1 planets can have atmospheres, and if so, what they are made of. For this, we surveyed the literature on TRAPPIST-1 about topics as broad as irradiation environment, planet formation and migration, orbital stability, effects of tides and Transit Timing Variations, transit observations, stellar contamination, density measurements, and numerical climate and escape models. Each of these topics adds a brick to our understanding of the likely—or on the contrary unlikely—atmospheres of the seven known planets of the system. We show that (i) Hubble Space Telescope transit observations, (ii) bulk density measurements comparison with H 2 -rich planets mass-radius relationships, (iii) atmospheric escape modelling, and (iv) gas accretion modelling altogether offer solid evidence against the presence of hydrogen-dominated—cloud-free and cloudy—atmospheres around TRAPPIST-1 planets. This means that the planets are likely to have either (i) a high molecular weight atmosphere or (ii) no atmosphere at all. There are several key challenges ahead to characterize the bulk composition(s) of the atmospheres (if present) of TRAPPIST-1 planets. The main one so far is characterizing and correcting for the effects of stellar contamination. Fortunately, a new wave of observations with the James Webb Space Telescope and near-infrared high-resolution ground-based spectrographs on existing very large and forthcoming extremely large telescopes will bring significant advances in the coming decade.

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A Reanalysis of the Fundamental Parameters and Age of TRAPPIST-1*

Cited by 32 publications

References 127 publications

The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs

The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs

TRAPPIST-1: Global results of theSpitzerExploration Science Program Red Worlds

A Review of Possible Planetary Atmospheres in the TRAPPIST-1 System

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