J/A+A/626/A111 Proxima Cen flare activity temporal changes (Pavlenko+, 2019)
Temporal changes of the flare activity of Proxima Centauri.
Pavlenko Ya.V., Suarez Mascareno A., Zapatero Osorio M.R., Rebolo R.,
Lodieu N., Bejar V.J.S., Gonzalez Hernandez J.I., Mohorian M.
<Astron. Astrophys. 626, A111 (2019)>
=2019A&A...626A.111P 2019A&A...626A.111P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Spectroscopy
Keywords: stars: activity - stars: atmospheres - stars: chromospheres -
stars: flare - stars: individual: Proxima Centauri
Abstract:
We study temporal variations of the emission lines of Hα,
Hε, H and K CaII, D1 and D2 NaI, He4026, and He5876 in the
HARPS spectra of Proxima Centauri across an extended time of 13.2yr,
from May 27, 2004 to September 30, 2017.
We analyse the common behaviour and differences in the intensities and
profiles of different emission lines in flare and quiet modes of
Proxima activity.
We compare the pseudo-equivalent widths (pEW) and profiles of the
emission lines in the HARPS high-resolution (R∼115000) 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 He4026 correlate with
Hα. During strong flares the "red asymmetry" appears in the
Hα emission line indicating the infall of hot condensed matter
into the chromosphere with velocities greater than 100km/s
disturbing chromospheric layers. As a result, the strength of the CaII
lines anti-correlates with Hα during strong flares. The HeI
lines at 4026 and 5876Å appear in the strong flares. The cores of
D1 and D2 NaI lines are also seen in emission. During the minimum
activity of Proxima Centauri, CaII lines and Hα almost disappear
while the blue part of the NaI emission lines is affected by the
absorption in the extending and condensing flows.
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.
Description:
We analysed 386 optical spectra obtained with HARPS, a fibre-fed,
echelle, high-resolution spectrograph installed on the 3.6-m European
Southern Observatory (ESO) telescope in the La Silla Observatory,
Chile. The instrument offers a resolving power of R∼115000 over a
spectral range from 3780 to 6810Å. The dates cover a time interval
of over 13yr, from Barycentric Julian dates (BJD) between 2453152.600,
that is the night of May 27, 2004, and 2456418.643, the night of
September 30, 2017.
Objects:
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RA (2000) DE Designation(s)
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14 29 42.95 -62 40 46.2 Proxima Cen = * alf Cen C
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 65 386 Pseudoequivalent widths (pEW) of some emission
lines measured in HARPS spectra observed on
dates BJD=2453152-2458027
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See also:
J/A+A/328/261 : Spectroscopy of Alpha Cen (Neuforge-Verheecke+ 1997)
J/A+A/406/L23 : Solar-like oscillations in alpha Cen B (Carrier+, 2003)
J/A+A/415/331 : HST/STIS spectra of alpha Cen A (Pagano+, 2004)
J/A+A/459/669 : JHKs photometry around α Cen (Kervella+, 2006)
J/A+A/464/373 : VRIZJHK photometry around Alpha Cen (Kervella+, 2007)
J/A+A/534/A133 : Proxima Cen chromospheric emission lines (Fuhrmeister+, 2011)
J/A+A/597/A137 : HD 123999 and Alpha Cen A and B OIFITS files (Kervella+, 2017)
J/A+A/615/A172 : alpha Cen A and B chemical composition (Morel, 2018)
J/AJ/155/24 : alpha Cen radial velocity & planet detectability (Zhao+, 2018)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 d BJD Baricentric Julian date (BJD-2450000)
11- 17 F7.3 0.1nm pEWHa Hα pseudo-equivalent width
19- 25 F7.3 0.1nm pEWCaIIK CaII(K) pseudo-equivalent width
27- 33 F7.3 0.1nm pEWCaIIH CaII(H) pseudo-equivalent width
35- 39 F5.3 0.1nm pEWHeI5876 He5876Å pseudo-equivalent width
41- 45 F5.3 0.1nm pEWHeI4026 He4026Å pseudo-equivalent width
47- 53 F7.3 0.1nm pEWHe Hε pseudo-equivalent width
55- 59 F5.3 0.1nm pEWNaID2 NaI(D2) pseudo-equivalent width
61- 65 F5.3 0.1nm pEWNaID1 NaI(D1) pseudo-equivalent width
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Acknowledgements:
Yakiv Pavlenko, email2yp(at)gmail.com
(End) Patricia Vannier [CDS] 27-May-2019