Time-resolved X-ray spectra of Proxima Centauri as seen by XMM-Newton

Abstract

Stellar soft X-ray ([1, 100] Angstrom) and Extreme Ultraviolet (also EUV, [100, 920] Angstrom; jointly, XUV) radiation affects the evolution and chemistry of exoplanet atmospheres. It is however uncertain to what extent the radiation's short-term variability contributes to these effects. We are interested in what this variability might imply for planets around M dwarf stars, and focus on Proxima Centauri (Prox Cen) for three reasons: it is an active M dwarf with high levels of variability; it hosts a likely terrestrial exoplanet within its habitable zone (HZ) that will be a prime target for future direct imaging; its proximity has led to extensive observations. We set out to produce time-resolved XUV spectra of Prox Cen that will serve as input to atmospheric models, and to characterize the intrinsic variability of the star. We analyzed the entire dataset of archival XMM-Newton observations for Prox Cen. To derive the time-resolved X-ray spectra, we implemented a new pile-up correction, a new adaptive time-binning algorithm, and a time-dependent plasma model selection. The estimated EUV spectrum is based on a published template, that we scale with proposed relationships between X-ray and EUV fluxes. We produced spectra of Prox Cen from 1 to 920 Angstrom over ~260 ks of observations with unprecedented time resolution. The instantaneous X-ray flux of Prox Cen varies between about 20 times and one-fifth of the average value over the available baseline, with significant differences between wavelengths. We further quantify how variability affects the estimated average flux when a limited number of snapshots (each typically of 30 ks exposure) are available, as is common in X-ray surveys. Future investigations of the atmospheres of Prox Cen b should fold in the time variability and uncertainties described here.

arXiv comment19 pages, 14 figures, 3 tables; Accepted for publication in A&A

References in corpus (44)

• On the Absorption of X-rays in the Interstellar Medium
• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• The XMM-Newton Optical/UV Monitor Telescope
• The Occurrence Rate of Small Planets around Small Stars
• Stellar Diameters and Temperatures II. Main Sequence K & M Stars
• The Effect of a Strong Stellar Flare on the Atmospheric Chemistry of an Earth-like Planet Orbiting an M dwarf
• Estimation of the XUV radiation onto close planets and their evaporation
• Trumpeting M Dwarfs with CONCH-SHELL: a Catalog of Nearby Cool Host-Stars for Habitable ExopLanets and Life
• The evolution of X-ray emission in young stars
• X-Ray Spectroscopy of Stars
• The active lives of stars: a complete description of rotation and XUV evolution of F, G, K, and M dwarfs
• The Intrinsic Extreme Ultraviolet Fluxes of F5 V to M5 V Stars
• The MUSCLES Treasury Survey. V. FUV Flares on Active and Inactive M Dwarfs
• Flares from small to large: X-ray spectroscopy of Proxima Centauri with XMM-Newton
• Optical, UV, and X-Ray Evidence for a 7-Year Stellar Cycle in Proxima Centauri
• The Mouse that Roared: A Superflare from the dMe Flare Star EV Lac detected by Swift and Konus-Wind
• Stellar coronal astronomy - a review
• Solar Energetic Particles (Second Edition)
• X-Ray Evidence for Flare Density Variations and Continual Chromospheric Evaporation in Proxima Centauri
• Multi-wavelength observations of Proxima Centauri
• HADES RV Programme with HARPS-N at TNG XII. The abundance signature of M dwarf stars with planets
• Modeling an X-ray Flare on Proxima Centauri: evidence of two flaring loop components and of two heating mechanisms at work
• The full spectral radiative properties of Proxima Centauri
• A study of X-ray flares - I. Active late-type dwarfs
• H$\alpha$ and He I absorption in HAT-P-32 b observed with CARMENES -- Detection of Roche lobe overflow and mass loss
• Coronal activity cycles in nearby G and K stars - XMM-Newton monitoring of 61 Cygni and Alpha Centauri
• On the uncertain nature of the core of $\mathbf{\alpha }$ Cen A
• No Conclusive Evidence for Transits of Proxima b in MOST photometry
• The X-ray cycle in the solar-type star HD 81809
• 3D modelling of the impact of stellar activity on tidally locked terrestrial exoplanets: atmospheric composition and habitability
• Connection between planetary He I $\lambda$10830 Å absorption and extreme-ultraviolet emission of planet-host stars
• Impact of stellar flares on the chemical composition and transmission spectra of gaseous exoplanets orbiting M dwarfs
• X-ray flares of the young planet host DS Tuc A
• The Mouse that Squeaked: A small flare from Proxima Cen observed in the millimeter, optical, and soft X-ray with Chandra and ALMA
• Diving into the planetary system of Proxima with NIRPS -- Breaking the metre per second barrier in the infrared
• Temporal changes of the flare activity of Proxima Cen
• Star-Planet Interactions: A Computational View
• XUV irradiation of young planetary atmospheres. Results from a joint XMM-Newton and HST observation of HIP67522
• The high energy spectrum of Proxima Centauri simultaneously observed at X-ray and FUV wavelengths
• Effects of transient stellar emissions on planetary climates of tidally-locked exo-earths
• Modelling helium in exoplanet atmospheres. A revised network with photoelectron-driven processes
• Far-ultraviolet flares and variability of the young M dwarf AU Mic: a non-detection of planet c in transit at Lyman-alpha