The relative emission from chromospheres and coronae: dependence on spectral type and age

Abstract

Extreme-ultraviolet and X-ray emissions from stellar coronae drive mass loss from exoplanet atmospheres, and ultraviolet emission from stellar chromospheres drives photo-chemistry in exoplanet atmospheres. Comparisons of the spectral energy distributions of host stars are, therefore, essential for understanding the evolution and habitability of exoplanets. The large number of stars observed with the MUSCLES, Mega-MUSCLES, and other recent HST observing programs has provided for the first time a large sample (79 stars) of reconstructed Lyman-alpha fluxes that we compare with X-ray fluxes to identify significant patterns in the relative emission from these two atmospheric regions as a function of stellar age and effective temperature. We find that as stars age on the main sequence, the emissions from their chromospheres and coronae follow a pattern in response to the amount of magnetic heating in these atmospheric layers. A single trendline slope describes the pattern of X-ray vs. Lyman-alpha emission for G and K dwarfs, but the different trendlines for M dwarf stars show that the Lyman-alpha fluxes of M stars are significantly smaller than warmer stars with the same X-ray flux. The X-ray and Lyman-alpha luminosities divided by the stellar bolometric luminosities show different patterns depending on stellar age. The L(Lyman-alpha)/L(bol) ratios increase smoothly to cooler stars of all ages, but the L(X)/L(bol) ratios show different trends. For older stars, the increase in coronal emission with decreasing T(eff) is much steeper than chromospheric emission. We suggest a fundamental link between atmospheric properties and trendlines relating coronal and chromospheric heating,

arXiv comment42 pages, 9 figures. To appear in the Astrophysical Journal

References in corpus (59)

• Evolution of the Solar Activity over Time and Effects on Planetary Atmospheres: I. High-energy Irradiances (1-1700 A)
• Theory of Low-Mass Stars and Substellar Objects
• Large-scale magnetic topologies of late M dwarfs
• X-ray astronomy of stellar coronae (Review)
• Estimation of the XUV radiation onto close planets and their evaporation
• The MUSCLES Treasury Survey I: Motivation and Overview
• The H$\alpha$ emission of nearby M dwarfs and its relation to stellar rotation
• The FIP and Inverse FIP Effects in Solar and Stellar Coronae
• The Habitability of Planets Orbiting M-dwarf Stars
• The first XMM-Newton slew survey catalogue: XMMSL1
• Stellar Lyman-alpha Emission Lines in the Hubble Space Telescope Archive: Intrinsic Line Fluxes and Absorption from the Heliosphere and Astrospheres
• The MUSCLES Treasury Survey II: Intrinsic Lyman Alpha and Extreme Ultraviolet Spectra of K and M Dwarfs with Exoplanets
• How to Characterize Habitable Worlds and Signs of Life
• The coronal X-ray - age relation and its implications for the evaporation of exoplanets
• The MUSCLES Treasury Survey III: X-ray to Infrared Spectra of 11 M and K Stars Hosting Planets
• Solar-type dynamo behaviour in fully convective stars without a tachocline
• Hubble PanCET: An extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470 b
• Observations of Cool-Star Magnetic Fields
• The UV and X-ray activity of the M dwarfs within 10pc of the Sun
• Radius Dependent Angular Momentum Evolution in Low-Mass Stars. I
• BANYAN. III. Radial velocity, Rotation and X-ray emission of low-mass star candidates in nearby young kinematic groups
• The Properties of the Solar Corona and Its Connection to the Solar Wind
• Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. III. X-ray, Radio, and H-alpha Activity Trends in M and L Dwarfs
• The MUSCLES Treasury Survey. V. FUV Flares on Active and Inactive M Dwarfs
• Strong XUV irradiation of the Earth-sized exoplanets orbiting the ultracool dwarf TRAPPIST-1
• The MUSCLES Treasury Survey IV: Scaling Relations for Ultraviolet, Ca II K, and Energetic Particle Fluxes from M Dwarfs
• BOSS Ultracool Dwarfs I: Colors and Magnetic Activity of M and L dwarfs
• Reconnaissance of the TRAPPIST-1 exoplanet system in the Lyman-$\alpha$ line
• Computing Intrinsic Lyman-alpha Fluxes of F5 V to M5 V Stars
• Time-resolved Ultraviolet Spectroscopy of the M-dwarf GJ 876 Exoplanetary System
• Rotation of Late-Type Stars in Praesepe with K2
• Semi-empirical Modeling of the Photosphere, Chromosphere, Transition Region, and Corona of the M-dwarf Host Star GJ 832
• Tracers of Chromospheric Structure I: Observations of Ca II K and H alpha in M Dwarfs
• Far-Ultraviolet Activity Levels of F, G, K, and M dwarf Exoplanet Host Stars
• A Gap in the Lower Main Sequence Revealed by Gaia Data Release 2
• Living with a Red Dwarf: Rotation and X-ray and Ultraviolet Properties of the Halo Population Kapteyn's Star
• The Global Solar Dynamo
• Fluctuations and Flares in the Ultraviolet Line Emission of Cool Stars: Implications for Exoplanet Transit Observations
• HAZMAT III: The UV Evolution of Mid- to Late-M Stars with GALEX
• Exploring the magnetic field complexity in M dwarfs at the boundary to full convection
• A Chandra/LETGS Survey of Main Sequence Stars
• Is pi Men c's atmosphere hydrogen-dominated? Insights from a non-detecton of Hy Ly-alpha absorption
• A closer look at the transition between fully convective and partly radiative low mass stars
• A He3 driven instability near the fully convective boundary
• Altair - the 'hottest' magnetically active star in X-rays
• The ultracool dwarf DENIS-P J104814.7-395606. Chromospheres and coronae at the low-mass end of the main-sequence
• Spot patterns and differential rotation in the eclipsing pre-CV binary,V471 Tau
• The Ups and Downs of Alpha Centauri
• HAZMAT. V. The Ultraviolet and X-ray Evolution of K Stars
• The Rotation-Activity Correlations in K and M dwarfs. II. New constraints on the dynamo mechanisms in late-K and M dwarfs before and at the transition to complete convection
• HAZMAT II: Ultraviolet Variability of Low-Mass Stars in the GALEX Archive
• Transition Region Emission From Very Low Mass Stars
• Studies of multiple stellar systems - IV. The triple-lined spectroscopic system Gliese 644
• Lyman-alpha in the GJ 1132 System: Stellar Emission and Planetary Atmospheric Evolution
• ROSAT observations of V471 Tauri, showing that stellar activity is determined by rotation, not age
• On the bio-habitability of M-dwarf planets
• The XUV irradiation and likely atmospheric escape of the super-Earth $\pi$ Men c
• Lyman-$\alpha$ Observations of High Radial Velocity Low-Mass Stars Ross 1044 and Ross 825
• The UV spectrum of the Ultracool Dwarf LSR J1835+3259 observed with the Hubble Space Telescope

Cited by in corpus (21)

• New Observational Constraints on the Winds of M Dwarf Stars
• Reconstructing the Extreme Ultraviolet Emission of Cool Dwarfs Using Differential Emission Measure Polynomials
• Grid of pseudo-2D chemistry models for tidally locked exoplanets -- II. The role of photochemistry
• The MUSCLES Extension for Atmospheric and Transmission Spectroscopy: UV and X-ray Host-star Observations for JWST ERS & GTO Targets
• Intrinsic Lyman alpha Profiles of High-Velocity G, K, and M Dwarfs
• Estimating the Ultraviolet Emission of M dwarfs with Exoplanets from Ca II and H$\alpha$
• HAZMAT. VII. The Evolution of Ultraviolet Emission with Age and Rotation for Early M Dwarf Stars
• A multi-wavelength look at the GJ 9827 system -- No evidence of extended atmospheres in GJ 9827 b and d from HST and CARMENES data
• Universal Scaling Laws for Solar and Stellar Atmospheric Heating: Catalog of Power-law Index between Solar Activity Proxies and Various Spectral Irradiances
• Reconstructing the XUV Spectra of Active Sun-like Stars Using Solar Scaling Relations with Magnetic Flux
• HAZMAT. VIII. A Spectroscopic Analysis of the Ultraviolet Evolution of K Stars: Additional Evidence for K Dwarf Rotational Stalling in the First Gigayear
• A Concise Treatise on Converting Stellar Mass Fractions to Abundances to Molar Ratios
• Coronal X-Ray Emission from Nearby, Low-Mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey Projects
• Mind the Gap I: H$\alpha$ Activity of M Dwarfs Near the Partially/Fully Convective Boundary and a New H$\alpha$ Emission Deficiency Zone on the Main Sequence
• UOCS-IX. AstroSat/UVIT study of the open cluster NGC 2818: Blue Stragglers, Yellow Stragglers, Planetary Nebula, and their membership
• Variation in the stellar initial mass function from the chromospheric activity of M dwarfs in early-type galaxies
• Accurate Modeling of Lyman-alpha Profiles and their Impact on Photolysis of Terrestrial Planet Atmospheres
• FUMES III: Ultraviolet and Optical Variability of M Dwarf Chromospheres
• Correlating Intrinsic Stellar Parameters with Mg II Self-Reversal Depths
• The GAPS programme at TNG -- LXIII. Photo-evaporating puzzle: Exploring the enigmatic nature of TOI-5398 b atmospheric signal
• Atmospheric mass loss and stellar wind effects in young and old systems I: comparative 3D study of TOI-942 and TOI-421 systems