X-ray Activity Variations and Coronal Abundances of the Star-Planet Interaction candidate HD 179949

Abstract

We carry out detailed spectral and timing analyses of the $Chandra$ X-ray data of HD 179949, a prototypical example of a star with a close-in giant planet with possible star-planet interaction (SPI) effects. We find a low coronal abundance $A(\mathrm{Fe})/A(\mathrm{H})\approx 0.2$ relative to the solar photospheric baseline of Anders & Grevesse (1989), and significantly lower than the stellar photosphere as well. We further find low abundances of high First Ionization Potential (FIP) elements $A(\mathrm{O})/A(\mathrm{Fe})\lesssim 1$, $A(\mathrm{Ne})/A(\mathrm{Fe})\lesssim 0.1$, but with indications of higher abundances of $A(\mathrm{N})/A(\mathrm{Fe})\gg 1,A(\mathrm{Al})/A(\mathrm{Fe})\lesssim 10$. We estimate a FIP bias for this star in the range $\approx -0.3$ to $-0.1$, larger than the $\lesssim -$0.5 expected for stars of this type, but similar to stars hosting close-in hot Jupiters. We detect significant intensity variability over time scales ranging from 100 s - 10 ks, and also evidence for spectral variability over time scales of 1-10 ks. We combine the $Chandra$ flux measurements with $Swift$ and XMM-$Newton$ measurements to detect periodicities and determine that the dominant signal is tied to the stellar polar rotational period, consistent with expectations that the corona is rotational-pole dominated. We also find evidence for periodicity at both the planetary orbital frequency and at its beat frequency with the stellar polar rotational period, suggesting the presence of a magnetic connection between the planet and the stellar pole. If these periodicities represent an SPI signal, it is likely driven by a quasi-continuous form of heating (e.g., magnetic field stretching) rather than sporadic, hot, impulsive flare-like reconnections.

arXiv comment26 pages, 12 figures, 11 tables. Accepted for publication in the Astrophysical Journal

References in corpus (56)

• The chemical composition of the Sun
• Gaia Data Release 2. Summary of the contents and survey properties
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• On the Absorption of X-rays in the Interstellar Medium
• Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions
• The VizieR database of Astronomical Catalogues
• Understanding the Lomb-Scargle Periodogram
• The Revised TESS Input Catalog and Candidate Target List
• Spectroscopic [Fe/H] for 98 extra-solar planet-host stars: Exploring the probability of planet formation
• Catalog of Nearby Exoplanets
• The stellar activity-rotation relationship and the evolution of stellar dynamos
• Statistics: Handle with Care, Detecting Multiple Model Components with the Likelihood Ratio Test
• Studies in Astronomical Time Series Analysis. VI. Bayesian Block Representations
• Spectral Properties of Cool Stars: Extended Abundance Analysis of 1617 Planet Search Stars
• Bayesian Estimation of Hardness Ratios: Modeling and Computations
• A Planetary Companion to gamma Cephei A
• The FIP and Inverse FIP Effects in Solar and Stellar Coronae
• The On/Off Nature of Star-Planet Interactions
• The elemental composition of the Sun II. The iron group elements Sc to Ni
• The photospheric solar oxygen project: I. Abundance analysis of atomic lines and influence of atmospheric models
• Chromospheric activity catalogue of 4454 cool stars. Questioning the active branch of stellar activity cycles
• NEXXUS: A comprehensive ROSAT survey of coronal X-ray emission among nearby solar-like stars
• On the use of C-stat in testing models for X-ray spectra
• The elemental composition of the Sun III. The heavy elements Cu to Th
• The "Solar Model Problem" Solved by the Abundance of Neon in Stars of the Local Cosmos
• Revealing A Universal Planet-Metallicity Correlation For Planets of Different Sizes Around Solar-Type Stars
• Are superflares on solar analogues caused by extra-solar planets?
• Coronal properties of planet-bearing stars
• Stellar coronal magnetic fields and star-planet interaction
• Magnetic field strengths of hot Jupiters from signals of star-planet interactions
• Age consistency between exoplanet hosts and field stars
• Extrasolar Giant Planets and X-ray Activity
• Analysis of Energy Spectra with Low Photon Counts via Bayesian Posterior Simulation
• Magnetic field, differential rotation and activity of the hot-Jupiter hosting star HD 179949
• Oxygen abundances in G- and F-type stars from HARPS
• Star-planet magnetic interaction and evaporation of planetary atmospheres
• Possible constraints on exoplanet magnetic field strengths from planet-star interaction
• The corona of HD 189733 and its X-ray activity
• A comprehensive statistical assessment of star-planet interaction
• Star-planet magnetic interaction and activity in late-type stars with close-in planets
• Coordinated X-ray and Optical observations of Star-Planet Interaction in HD 17156
• Stellar Activity and Coronal Heating: an overview of recent results
• Nitrogen abundances in Planet-harbouring stars
• Parent Stars of Extrasolar Planets. VIII. Chemical Abundances for 18 Elements in 31 Stars
• A Chandra/LETGS Survey of Main Sequence Stars
• No X-rays from WASP-18. Implications for its age, activity, and the influence of its massive hot Jupiter
• CNO behaviour in planet-harbouring stars. II. Carbon abundances in stars with and without planets using the CH band
• A Catalog of Stellar Unified Properties (CATSUP) for 951 FGK-Stars Within 30 pc
• The Coronal Abundance Anomalies of M Dwarfs
• The stellar content of the ROSAT all-sky survey
• Planet-Induced Emission Enhancements in HD 179949: Results from McDonald Observations
• A statistical search for Star-Planet Interaction in the UltraViolet using GALEX
• X-ray intraday variability of the TeV blazar Mrk 421 with {\it XMM-Newton}
• X-ray variability of HD 189733 across eight years of XMM-Newton observations
• Concordance: In-flight Calibration of X-ray Telescopes without Absolute References
• Relative Abundance Measurements in Plumes and Interplumes

Cited by in corpus (1)

• Spectral fit residuals as an indicator to increase model complexity