A combined spectroscopic and photometric stellar activity study of Epsilon Eridani

Abstract

We present simultaneous ground-based radial velocity (RV) measurements and space-based photometric measurements of the young and active K dwarf Epsilon Eridani. These measurements provide a data set for exploring methods of identifying and ultimately distinguishing stellar photospheric velocities from Keplerian motion. We compare three methods we have used in exploring this data set: Dalmatian, an MCMC spot modeling code that fits photometric and RV measurements simultaneously; the FF${}^{\prime }$ method, which uses photometric measurements to predict the stellar activity signal in simultaneous RV measurements; and H$\alpha$ analysis. We show that our H$\alpha$ measurements are strongly correlated with photometry from the Microvariability and Oscillations of STars (MOST) instrument, which led to a promising new method based solely on the spectroscopic observations. This new method, which we refer to as the HH${}^{\prime }$ method, uses H$\alpha$ measurements as input into the FF${}^{\prime }$ model. While the Dalmatian spot modeling analysis and the FF${}^{\prime }$ method with MOST space-based photometry are currently more robust, the HH${}^{\prime }$ method only makes use of one of the thousands of stellar lines in the visible spectrum. By leveraging additional spectral activity indicators, we believe the HH${}^{\prime }$ method may prove quite useful in disentangling stellar signals.

References in corpus (12)

• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• Stellar Activity Masquerading as Planets in the Habitable Zone of the M dwarf Gliese 581
• The HARPS search for southern extra-solar planets. X. A m sin i = 11 Mearth planet around the nearby spotted M dwarf GJ 674
• Stellar activity of planetary host star HD 189733
• Barycentric Corrections at 1 cm/s for precise Doppler velocities
• Magnetic Activity Cycles in the Exoplanet Host Star epsilon Eridani
• Accurate Gravities of F, G, and K stars from High Resolution Spectra Without External Constraints
• Newly-Discovered Planets Orbiting HD~5319, HD~11506, HD~75784 and HD~10442 from the N2K Consortium
• High-contrast Imaging with Spitzer: Deep Observations of Vega, Fomalhaut, and epsilon Eridani
• The differential rotation of epsilon Eri from MOST data
• Photospheric and chromospheric activity in four young solar-type stars
• Modeling sunspot and starspot decay by turbulent erosion

Cited by in corpus (18)

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• Insights on the Spectral Signatures of Stellar Activity and Planets from PCA
• The EXPRES Stellar Signals Project II. State of the Field in Disentangling Photospheric Velocities
• The Northern Arc of $\epsilon$ Eridani's Debris Ring as Seen by ALMA
• Multi-instrumental view of magnetic fields and activity of $\epsilon$ Eridani with SPIRou, NARVAL, and TESS
• The crucial role of surface magnetic fields for stellar dynamos: Epsilon Eridani, 61 Cygni A, and the Sun
• EXPRES. III. Revealing the Stellar Activity Radial Velocity Signature of $\epsilon$ Eridani with Photometry and Interferometry
• The death of Vulcan: NEID reveals the planet candidate orbiting HD 26965 is stellar activity
• EXPRES. II. Searching for Planets Around Active Stars: A Case Study of HD 101501
• Into the Depths: a new activity metric for high-precision radial velocity measurements based on line depth variations
• Solar Photospheric Spectrum Microvariability I. Theoretical searches for proxies of radial-velocity jittering
• A Stellar Activity F-statistic for Exoplanet Surveys (SAFE)
• The impact of unresolved magnetic spots on high precision radial velocity measurements
• Quiet Please: Detrending Radial Velocity Variations from Stellar Activity with a Physically Motivated Spot Model
• The Effects of Sunspots on Spectral Line Shapes in the Visible
• Minimal Data Fidelity for Detection of Stellar Features or Companions
• Direct Imaging for the Debris Disk around $\epsilon$ Eridani with the Cool-Planet Imaging Coronagraph
• Sunspot and starspot lifetimes in a turbulent erosion model