Temporal changes of the flare activity of Proxima Cen

Abstract

We study temporal variations of the emission lines of Halpha, Hepsilon, H and K Ca II, D1 and D2 Na I, 4026 and 5876 A He I in the HARPS spectra of Proxima Centauri across an extended time of 13.2 years, from May 27, 2004, to September 30, 2017. Aims. We analyse the common behaviour and differences in the intensities and profiles of different emission lines in flare and quiet modes of Proxima activity. Methods. We compare the pseudo-equivalent widths (pEW) and profiles of the emission lines in the HARPS high-resolution (R ~ 115,000) spectra observed at the same epochs. Results. All emission lines show variability with a timescale of at least 10 min. The strength of all lines except He I 4026 A correlate with \Halpha. During strong flares the `red asymmetry' appears in the Halpha emission line indicating the infall of hot condensed matter into the chromosphere with velocities greater than 100 km/s disturbing chromospheric layers. As a result, the strength of the Ca II lines anti-correlates with Halpha during strong flares. The He I lines at 4026 and 5876 A appear in the strong flares. The cores of D1 and D2 Na I lines are also seen in emission. During the minimum activity of Proxima Centauri, Ca II lines and Hepsilon almost disappear while the blue part of the Na I emission lines is affected by the absorption in the extending and condensing flows. Conclusions. We see different behaviour of emission lines formed in the flare regions and chromosphere. Chromosphere layers of Proxima Cen are likely heated by the flare events; these layers are cooled in the `non-flare' mode. The self-absorption structures in cores of our emission lines vary with time due to the presence of a complicated system of inward and outward matter flows in the absorbing layers.

arXiv comment22 pages, 12 Figures, accepted by AA

References in corpus (43)

• The Sloan Digital Sky Survey: Technical Summary
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• An Observational Overview of Solar Flares
• A super-Earth transiting a nearby low-mass star
• Transiting exoplanets from the CoRoT space mission VIII. CoRoT-7b: the first Super-Earth with measured radius
• Large-scale magnetic topologies of late M dwarfs
• Kepler Flares I. Active and Inactive M dwarfs
• The HARPS search for southern extra-solar planets XI. Super-Earths (5 & 8 M_Earth) in a 3-planet system
• Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243
• The rotation and Galactic kinematics of mid M dwarfs in the Solar Neighborhood
• Chromospheric Activity, Rotation, and Rotational Braking in M and L Dwarfs
• On the angular momentum evolution of fully-convective stars: rotation periods for field M-dwarfs from the MEarth transit survey
• Rotation periods of late-type dwarf stars from time-series high-resolution spectroscopy of chromospheric indicators
• White-light flares on cool stars in the Kepler Quarter 1 Data
• Angular Momentum Loss from Cool Stars: An Empirical Expression and Connection to Stellar Activity
• Transit Detection in the MEarth Survey of Nearby M Dwarfs: Bridging the Clean-First, Search-Later Divide
• The stable magnetic field of the fullly-convective star V374 Peg
• An Activity-Rotation Relationship and Kinematic Analysis of Nearby Mid-to-Late-type M Dwarfs
• Stellar rotation in the Hyades and Praesepe: gyrochronology and braking timescale
• M Dwarfs in SDSS Stripe 82: Photometric Light Curves and Flare Rate Analysis
• Validation of Twelve Small Kepler Transiting Planets in the Habitable Zone
• Long-term magnetic activity of a sample of M-dwarf stars from the HARPS program II. Activity and radial velocity
• Optical, UV, and X-Ray Evidence for a 7-Year Stellar Cycle in Proxima Centauri
• The First Naked-Eye Superflare Detected from Proxima Centauri
• Photometry of Proxima Centauri and Barnard's Star Using HST Fine Guidance Sensor 3: A Search for Periodic Variations
• MOST Observations of our Nearest Neighbor: Flares on Proxima Centauri
• Multi-wavelength observations of Proxima Centauri
• The HARPS search for southern extra-solar planets XXXV. Planetary systems and stellar activity of the M dwarfs GJ 3293, GJ 3341, and GJ 3543
• The effect of M dwarf starspot activity on low-mass planet detection thresholds
• Characterisation of the radial velocity signal induced by rotation in late-type dwarfs
• Chromospheric Condensation and Quasi-periodic Pulsations in a Circular-ribbon Flare
• Investigating the Rotational Phase of Stellar Flares on M dwarfs Using K2 Short Cadence Data
• New Planetary Systems from the Calan-Hertfordshire Extrasolar Planet Search
• Characterizing a Dramatic $\Delta V\sim -9$ Flare on an Ultracool Dwarf Found by the ASAS-SN Survey
• The Changing Face of $\alpha$ Centauri B: Probing plage and stellar activity in K-dwarfs
• Three planets orbiting Wolf 1061
• Optical Spectroscopy of a Flare on Barnard's Star
• A connection between the morphology of the X-ray emission and rotation for solar-type stars in open clusters
• A short-period super-Earth orbiting the M2.5 dwarf GJ3634. Detection with Harps velocimetry and transit search with Spitzer photometry
• Internal and relative motions of the Taurus and Ophiuchus star-forming regions
• Flare activity and photospheric analysis of Proxima Centauri
• Calculations of periodicity from Hα profiles of Proxima Centauri

Cited by in corpus (8)

• Flaring activity of Proxima Centauri from TESS observations: quasi-periodic oscillations during flare decay and inferences on the habitability of Proxima b
• A census of Coronal Mass Ejections on solar-like stars
• AlH lines in the blue spectrum of Proxima Centauri
• The CARMENES search for exoplanets around M dwarfs. Behaviour of the Paschen lines during flares and quiescence
• Formation of H$\epsilon$ in the solar atmosphere
• Dissecting the Quadruple Binary Hyad vA 351 -- Masses for three M Dwarfs and a White Dwarf
• On the Origin of Optical Radiation During the Impulsive Phase of Flares on dMe Stars. II. Continuum and Line Radiation
• Time-resolved X-ray spectra of Proxima Centauri as seen by XMM-Newton