J/MNRAS/495/4529 Flare cumulative frequencies of UV Ceti stars (Dal+, 2020)
The flare cumulative frequencies of UV Ceti stars from different spectral types.
Dal H.A.
<Mon. Not. R. Astron. Soc., 495, 4529-4541 (2020)>
=2020MNRAS.495.4529D 2020MNRAS.495.4529D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, flare ; Stars, activity ; Photometry, UBV
Keywords: methods: data analysis - methods: statistical - stars: activity -
stars: flare - stars: late-type
Abstract:
In this study, as a result of the photometric observations continued
on nine UV Ceti type stars, examining the parameters obtained from the
models of distributions of the flare equivalent durations in the
logarithmic scale versus flare total durations, it is found that the
highest flare equivalent durations occurring on the stars (Plateau
values) are varying with the B-V colour indexes of those stars in
agreement with the variations of both the magnetic field strength (B)
of the magnetic loop and especially the electron density of its plasma
(ne). The distributions of flare cumulative frequencies were derived
by using the flare equivalent durations, instead of the flare energy.
The main result of this study is a secondary variation, which can be
just modelled with the damping sine waves, behind the main exponential
variation of the flare cumulative frequency. The models indicate that
this secondary variation in the flare cumulative frequency
distributions is in the same shape with the periodic or quasi-periodic
oscillations detected in the light curves of the stellar and solar
flares. This caused to ask new questions about the flare mechanism
working on stellar atmospheres.
Description:
The unpublished data were acquired with a High-Speed Three Channel
Photometer attached to a 48 cm Cassegrain type telescope in Ege
University Observatory. Using a tracking star set in the second
channel of photometer, the observations were continued in standard
Johnson U and B bands with the exposure times between 2 and 10s.
12 U-band flares from the observations of V577 Mon, 18 U-band flares
from V1054 Oph, 89 B-band flares from V1285 Aql, 48 B-band flares from
DO Cep, and 8 B-band flares from CR Dra were determined in the
analyses. The flare rise time, decay time, amplitude, and equivalent
duration were computed from the light curve of each flare. The
procedure used in the calculations is similar to the methods described
in Gershberg (1972Ap&SS..19...75G 1972Ap&SS..19...75G).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 33 5 Stars studied in this work
table1.dat 55 170 All U- and B-band flares detected from the
observations of five stars and their parameters
are listed for five flares
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name
11- 12 I2 h RAh Right ascension (J2000)
14- 15 I2 min RAm Right ascension (J2000)
17- 21 F5.2 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 33 F4.1 arcsec DEs Declination (J2000)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name
11 A1 --- Band Observation band
13- 23 F11.5 d Tflare Heliocentric Julian date of the flare maximum
(HJD-2400000)
25- 34 F10.5 s P Flare equivalent duration
36- 39 I4 s taur Flare rise time
41- 44 I4 s taud Flare decay time
46- 49 I4 s taut Flare total duration
51- 55 F5.3 --- Amp Flare amplitude in turn
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 23-Jun-2023