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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.
We present the analysis of emission lines in high-resolution optical spectra of the planet-host star Proxima Centauri (Proxima) classified as a M5.5V@. We carry out the detailed analysis of observed spectra to get a better understanding of the physic
We analyze the light curve of 1740 flare stars to study the relationship between the magnetic feature characteristics and the identified flare activity. Coverage and stability of magnetic features are inspired by rotational modulation of light curve
We report the detection of a large-scale magnetic field at the surface of the slowly-rotating fully-convective M dwarf Proxima Centauri. Ten circular polarization spectra, collected from April to July 2017 with the HARPS-Pol spectropolarimeter, exhib
We present new analyses of ALMA 12-m and ACA observations at 233 GHz (1.3 mm) of the Proxima Centauri system with sensitivities of 9.5 and 47 $mu$Jy beam$^{-1}$, respectively, taken from 2017 January 21 through 2017 April 25. These analyses reveal th
Context: Classical nova progenitors are cataclysmic variables and very old novae are observed to match high mass transfer rate and (relatively) long orbital period systems. However, the aftermath of a classical nova has never been studied in detail.