Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userOn the Age of the TRAPPIST-1 System
81
0
0.0
(
0
)
Authors
Adam J. Burgasser
Ask ChatGPT about the research
No Arabic abstract
The nearby (d = 12 pc) M8 dwarf star TRAPPIST-1 (2MASS J23062928-0502285) hosts a compact system of at least seven exoplanets with sizes similar to Earth. Given its importance for testing planet formation and evolution theories, and for assessing the prospects for habitability among Earth-size exoplanets orbiting the most common type of star in the Galaxy, we present a comprehensive assessment of the age of this system. We collate empirical age constraints based on the color-absolute magnitude diagram, average density, lithium absorption, surface gravity features, metallicity, kinematics, rotation, and magnetic activity; and conclude that TRAPPIST-1 is a transitional thin/thick disk star with an age of 7.6$pm$2.2 Gyr. The stars color-magnitude position is consistent with it being slightly metal-rich ([Fe/H] $simeq$ +0.06), in line with its previously reported near-infrared spectroscopic metallicity; and it has a radius (R = 0.121$pm$0.003 R$_{odot}$) that is larger by 8-14% compared to solar-metallicity evolutionary models. We discuss some implications of the old age of this system with regard to the stability and habitability of its planets.
rate research
Read More
The signatures of planets hosted by M dwarfs are more readily detected with transit photometry and radial velocity methods than those of planets around larger stars. Recently, transit photometry was used to discover seven planets orbiting the late-M dwarf TRAPPIST-1. Three of TRAPPIST-1s planets fall in the Habitable Zone, a region where liquid water could exist on the planetary surface given appropriate planetary conditions. We aim to investigate the habitability of the TRAPPIST-1 planets by studying the stars activity and its effect on the planets. We analyze previously-published space- and ground-based light curves and show the photometrically-determined rotation period of TRAPPIST-1 appears to vary over time due to complicated, evolving surface activity. The dramatic changes of the surface of TRAPPIST-1 suggest that rotation periods determined photometrically may not be reliable for this and similarly active stars. While the activity of the star is low, we use the premise of the cosmic shoreline to provide evidence that the TRAPPIST-1 environment has potentially led to the erosion of possible planetary atmospheres by extreme ultraviolet stellar emission.
Protoplanetary discs around brown dwarfs and very low mass stars offer some of the best prospects for forming Earth-sized planets in their habitable zones. To this end, we study the nature of the disc around the very low mass star V410 X-ray 1, whose SED is indicative of an optically thick and very truncated dust disc, with our modelling suggesting an outer radius of only 0.6 au. We investigate two scenarios that could lead to such a truncation, and find that the observed SED is compatible with both. The first scenario involves the truncation of both the dust and gas in the disc, perhaps due to a previous dynamical interaction or the presence of an undetected companion. The second scenario involves the fact that a radial location of 0.6 au is close to the expected location of the H$_2$O snowline in the disc. As such, a combination of efficient dust growth, radial migration, and subsequent fragmentation within the snowline leads to an optically thick inner dust disc and larger, optically thin outer dust disc. We find that a firm measurement of the CO $J=2$--1 line flux would enable us to distinguish between these two scenarios, by enabling a measurement of the radial extent of gas in the disc. Many models we consider contain at least several Earth-masses of dust interior to 0.6 au, suggesting that V410 X-ray 1 could be a precursor to a system with tightly-packed inner planets, such as TRAPPIST-1.
We present detailed characterization of the extremely dusty main sequence star TYC 8830 410 1. This system hosts inner planetary system dust (Tdust~300 K) with a fractional infrared luminosity of ~1%. Mid-infrared spectroscopy reveals a strong, mildy-crystalline solid-state emission feature. TYC 8830 410 1 (spectral type G9V) has a 49.5 separation M4-type companion co-moving and co-distant with it, and we estimate a system age of ~600 Myr. TYC 8830 410 1 also experiences dipper-like dimming events as detected by ASAS-SN, TESS, and characterized in more detail with the LCOGT. These recurring eclipses suggest at least one roughly star-sized cloud of dust orbits the star in addition to assorted smaller dust structures. The extreme properties of the material orbiting TYC 8830 410 1 point to dramatic dust-production mechanisms that likely included something similar to the giant-impact event thought to have formed the Earth-Moon system, although hundreds of millions of years after such processes are thought to have concluded in the solar system. TYC 8830 410 1 holds promise to deliver significant advances in our understanding of the origin, structure, and evolution of extremely dusty inner planetary systems.
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. Since the announcement of the discovery of TRAPPIST-1 planets in 2016, a growing number of techniques and approaches have been used and proposed to reveal 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, orbital architecture, transit observations, density measurements, stellar contamination, and numerical climate and escape models. Each of these topics adds a brick to our understanding of the likely atmospheres of the seven planets. We show that (i) HST transit observations, (ii) density measurements, (iii) atmospheric escape modelling, and (iv) gas accretion modelling altogether offer solid evidence against the presence of H2-dominated atmospheres around TRAPPIST-1 planets. This means they likely have either (i) a high molecular weight atmosphere or (ii) no atmosphere at all. There are several key challenges ahead to characterize the bulk compositions 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 very large telescopes will bring significant advances in the coming decade.
In an effort to measure the Rossiter-McLaughlin effect for the TRAPPIST-1 system, we performed high-resolution spectroscopy during transits of planets e, f, and b. The spectra were obtained with the InfraRed Doppler spectrograph on the Subaru 8.2-m telescope, and were supplemented with simultaneous photometry obtained with a 1-m telescope of the Las Cumbres Observatory Global Telescope. By analyzing the anomalous radial velocities, we found the projected stellar obliquity to be $lambda=1pm 28$ degrees under the assumption that the three planets have coplanar orbits, although we caution that the radial-velocity data show correlated noise of unknown origin. We also sought evidence for the expected deformations of the stellar absorption lines, and thereby detected the Doppler shadow of planet b with a false alarm probability of $1.7,%$. The joint analysis of the observed residual cross-correlation map including the three transits gave $lambda=19_{-15}^{+13}$ degrees. These results indicate that the the TRAPPIST-1 star is not strongly misaligned with the common orbital plane of the planets, although further observations are encouraged to verify this conclusion.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
