Characterising exo-ringsystems around fast-rotating stars using the Rossiter-McLaughlin effect

Abstract

Planetary rings produce a distinct shape distortion in transit lightcurves. However, to accurately model such lightcurves the observations need to cover the entire transit, especially ingress and egress, as well as an out-of-transit baseline. Such observations can be challenging for long period planets, where the transits may last for over a day. Planetary rings will also impact the shape of absorption lines in the stellar spectrum, as the planet and rings cover different parts of the rotating star (the Rossiter-McLaughlin effect). These line-profile distortions depend on the size, structure, opacity, obliquity and sky projected angle of the ring system. For slow rotating stars, this mainly impacts the amplitude of the induced velocity shift, however, for fast rotating stars the large velocity gradient across the star allows the line distortion to be resolved, enabling direct determination of the ring parameters. We demonstrate that by modeling these distortions we can recover ring system parameters (sky-projected angle, obliquity and size) using only a small part of the transit. Substructure in the rings, e.g. gaps, can be recovered if the width of the features ($\delta W$) relative to the size of the star is similar to the intrinsic velocity resolution (set by the width of the local stellar profile, $\gamma$) relative to the stellar rotation velocity ($v$ sin$i$, i.e. $\delta W/R_{\ast }\gtrsim v$sin$i$/$\gamma$). This opens up a new way to study the ring systems around planets with long orbital periods, where observations of the full transit, covering the ingress and egress, are not always feasible.

arXiv commentAccepted for publication in MNRAS

References in corpus (19)

• A ring system detected around the Centaur (10199) Chariklo
• Exoplanetary Spin-Orbit Alignment: Results from the Ensemble of Rossiter-McLaughlin Observations
• Orbital characterization of the βPictoris b giant planet
• The Rossiter-McLaughlin effect reloaded: Probing the 3D spin-orbit geometry, differential stellar rotation, and the spatially-resolved stellar spectrum of star-planet systems
• Photometric Amplitude Distribution of Stellar Rotation of Kepler KOIs-Indication for Spin-Orbit Alignment of Cool Stars and High Obliquity for Hot Stars
• Planetary Construction Zones in Occultation: Discovery of an Extrasolar Ring System Transiting a Young Sun-like Star and Future Prospects for Detecting Eclipses by Circumsecondary and Circumplanetary Disks
• $\beta$ Pictoris' inner disk in polarized light and new orbital parameters for $\beta$ Pictoris b
• Did Saturn's rings form during the Late Heavy Bombardment ?
• A Combined VLT and Gemini Study of the Atmosphere of the Directly-Imaged Planet, beta Pictoris b
• Modeling giant extrasolar ring systems in eclipse and the case of J1407b: sculpting by exomoons?
• The Orbit and Transit Prospects for $\beta$ Pictoris b constrained with One Milliarcsecond Astrometry
• Predicting Photometric and Spectroscopic Signatures of Rings around Transiting Extrasolar Planets
• A 5 Micron Image of beta Pictoris b at a Sub-Jupiter Projected Separation: Evidence for a Misalignment Between the Planet and the Inner, Warped Disk
• On the alignment of debris disks and their host stars' rotation axis -implications for spin-orbit misalignment in exoplanetary systems
• Alignment in star-debris disc systems seen by Herschel
• The B-ring's surface mass density from hidden density waves: Less than meets the eye?
• Physical collisions of moonlets and clumps with the Saturn's F-ring core
• The orbit of Beta Pic b as a transiting planet
• Is Beta Pic b the transiting planet of November 1981?

Cited by in corpus (13)

• Dynamical Constraints on the HR 8799 Planets with GPI
• Detection of Na, K, and H$\alpha$ absorption in the atmosphere of WASP-52b using ESPRESSO
• Detection of ionized calcium in the atmosphere of the ultra-hot Jupiter KELT-9b
• Transmission spectroscopy and Rossiter-McLaughlin measurements of the young Neptune orbiting AU Mic
• Can planetary rings explain the extremely low density of HIP 41378f?
• Activity induced variation in spin-orbit angles as derived from Rossiter-McLaughlin measurements
• A Framework for Characterizing Transmission Spectra of Exoplanets with Circumplanetary Rings
• A Circumplanetary Dust Ring May Explain the Extreme Spectral Slope of the 10 Myr Young Exoplanet K2-33b
• The PDS 110 observing campaign - photometric and spectroscopic observations reveal eclipses are aperiodic
• Spectroscopic Transit Search: a self-calibrating method for detecting planets around bright stars
• Mean Motion Resonances With Nearby Moons: An Unlikely Origin For The Gaps Observed In The Ring Around The Exoplanet J1407b
• Exploring Exoplanet Dynamics with JWST: Tides, Rotation, Rings, and Moons
• Search for Exoplanetary Ring Systems with TESS