Possible Bright Starspots on TRAPPIST-1.

  title={Possible Bright Starspots on TRAPPIST-1.},
  author={Brett M. Morris and Eric Agol and James. R. A. Davenport and Suzanne L. Hawley},
  journal={arXiv: Solar and Stellar Astrophysics},
The M8V star TRAPPIST-1 hosts seven roughly Earth-sized planets and is a promising target for exoplanet characterization. Kepler/K2 Campaign 12 observations of TRAPPIST-1 in the optical show an apparent rotational modulation with a 3.3 day period, though that rotational signal is not readily detected in the Spitzer light curve at 4.5 $\mu$m. If the rotational modulation is due to starspots, persistent dark spots can be excluded from the lack of photometric variability in the Spitzer light curve… 
Time-resolved image polarimetry of TRAPPIST-1 during planetary transits
We obtained linear polarization photometry ($J$-band) and low-resolution spectroscopy ($ZJ$-bands) of Trappist-1, which is a planetary system formed by an M8-type low-mass star and seven temperate,
Constraining the Radio Emission of TRAPPIST-1
TRAPPIST-1 is an ultracool dwarf (UCD) with a system of 7 terrestrial planets, at least three of which orbit in the habitable zone. The radio emission of such low-mass stars is poorly understood; few
Disentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1g
The atmospheres of late M stars represent a significant challenge in the characterization of any transiting exoplanets due to the presence of strong molecular features in the stellar atmosphere.
Simulating radial velocity observations of trappist-1 with SPIRou
  • B. Klein, J. Donati
  • Geology, Physics
    Monthly Notices of the Royal Astronomical Society
  • 2019
We simulate a radial velocity (RV) follow-up of the TRAPPIST-1 system, a faithful representative of M dwarfs hosting transiting Earth-sized exoplanets to be observed with SPIRou in the months to
Multifilter Observations of the Complex Periodic Variations in the M-dwarf Star RIK 90
  • C. Koen
  • Physics
    The Astronomical Journal
  • 2021
The star RIK 90 is a member of a group of recently discovered young T Tauri stars showing complex periodic modulations of their light output, which have been difficult to explain. As one of the
Magnetic Fields on the Flare Star Trappist-1: Consequences for Radius Inflation and Planetary Habitability
We construct evolutionary models of Trappist-1 in which magnetic fields impede the onset of convection according to a physics-based criterion. In the models that best fit all observational
Exoplanet transits with next-generation radio telescopes
Nearly everything we know about extrasolar planets to date comes from optical astronomy. While exoplanetary aurorae are predicted to be bright at low radio frequencies (< 1 GHz), we consider the
A Deep Radio Limit for the TRAPPIST-1 System
The first nearby very-low-mass star–planet-host discovered, TRAPPIST-1, presents not only a unique opportunity for studying a system of multiple terrestrial planets, but a means to probe
Ground-based follow-up observations of TRAPPIST-1 transits in the near-infrared
The TRAPPIST-1 planetary system is a favourable target for the atmospheric characterization of temperate earth-sized exoplanets by means of transmission spectroscopy with the forthcoming James Webb
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We report the discovery and characterisation of a super-Earth and a sub-Neptune transiting the bright (K = 8.8), quiet, and nearby (37 pc) M3V dwarf TOI-1266. We validate the planetary nature of


We present an analysis of the starspots on the active M4 dwarf GJ 1243, using 4 years of time series photometry from Kepler. A rapid P = 0.592596 ? 0.00021 days rotation period is measured due to the
The Starspots of HAT-P-11: Evidence for a Solar-like Dynamo
We measure the starspot radii and latitude distribution on the K4 dwarf HAT-P-11 from Kepler short-cadence photometry. We take advantage of starspot occultations by its highly-misaligned planet to
Starspots: The zebra effect
Recent observations of brightness variations on the Sun during the solar cycle have motivated us to re-examine the widely held view that cool, dark starspots, covering a significant fraction of the
The Stellar Activity of TRAPPIST-1 and Consequences for the Planetary Atmospheres
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
Placing the spotted T Tauri star LkCa 4 on an HR diagram
Ages and masses of young stars are often estimated by comparing their luminosities and effective temperatures to pre-main sequence stellar evolution tracks, but magnetic fields and starspots
Kepler Flares I. Active and Inactive M dwarfs
We analyzed Kepler short-cadence M dwarf observations. Spectra from the ARC 3.5m telescope identify magnetically active (H$\alpha$ in emission) stars. The active stars are of mid-M spectral type,
A seven-planet resonant chain in TRAPPIST-1
The TRAPPIST-1 system is the first transiting planet system found orbiting an ultra-cool dwarf star. At least seven planets similar to Earth in radius and in mass were previously found to transit
Early 2017 observations of TRAPPIST-1 with Spitzer
The recently detected TRAPPIST-1 planetary system, with its seven planets transiting a nearby ultracool dwarf star, offers the first opportunity to perform comparative exoplanetology of temperate
Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
The observations reveal that at least seven planets with sizes and masses similar to those of Earth revolve around TRAPPIST-1, and the six inner planets form a near-resonant chain, such that their orbital periods are near-ratios of small integers.
Dynamo processes and activity cycles of the active stars AB Doradus, LQ Hydrae and HR 1099
In this paper, we present new brightness and magnetic surface images of the young K0 dwarfs AB Doradus and LQ Hydrae, and of the K1 subgiant of the RS CVn system HR 1099 (=V711 Tauri), reconstructed