2007A&A...465..235Z


C.D.S. - SIMBAD4 rel 1.7 - 2019.10.16CEST10:10:24

2007A&A...465..235Z - Astronomy and Astrophysics, volume 465, 235-240 (2007/4-1)

Fast colorimetry of the flare star EV Lacertae from UBVRI observations in 2004.

ZHILYAEV B.E., ROMANYUK Y.O., SVYATOGOROV O.A., VERLYUK I.A., KAMINSKY B., ANDREEV M., SERGEEV A.V., GERSHBERG R.E., LOVKAYA M.N., AVGOLOUPIS S.J., SEIRADAKIS J.H., CONTADAKIS M.E., ANTOV A.P., KONSTANTINOVA-ANTOVA R.K. and BOGDANOVSKI R.

Abstract (from CDS):

We report results of a quantitative colorimetric UBVRI analysis of two flare events on the red dwarf EV Lac. The photometric data were obtained in September 2004, during the multi-site synchronous monitoring from the four observatories in Ukraine, Russia, Greece, and Bulgaria. These observations confirmed the presence of small-scale high-frequency oscillations (HFO) initially detected by Rodono (1974, A&A, 32, 337) and recently reconfirmed by the authors. Here we discuss the color characteristics of flares and HFO. Colorimetric analysis had been performed with the help of the time tracks in the UBVRI color-color diagrams from the earliest phase of flare development. Digital filtering technique was used to evaluate the time-dependent color indices. As can be clearly seen in the diagrams, color indices oscillate on a time scale of seconds, far exceeding instrumental errors. Regarding the HFO, we conclude that the bulk of a flare oscillates during a major part of its lifetime between the states of hydrogen plasma opaque and transparent in the Balmer continuum. We find that at the peaks of oscillations the color tracks drift into the regions of color-color diagrams corresponding to a blackbody radiation, which provides an estimate of color temperatures from 17000 to 22000K. We also find that flares cover ∼1% of the stellar disc.

Abstract Copyright:

Journal keyword(s): stars: flare - stars: individual: EV Lac - stars: activity

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 G 272-61B Fl* 01 39 01.6334059022 -17 57 01.121866655     13.2     M6V 780 0
2 V* YZ CMi BY* 07 44 40.1726285952 +03 33 08.877830321 13.761 12.831 11.225 9.958 8.263 M4.0Ve 767 0
3 BD+20 2465 ** 10 19 36.2808024653 +19 52 12.014037746   10.82 9.52 9.19   M4Vae 1111 0
4 NAME Barnard's star BY* 17 57 48.4997994034 +04 41 36.111354228 12.497 11.24 9.511 8.298 6.741 M4V 622 2
5 V* AT Mic ** 20 41 51.15925 -32 26 06.8283 12.753 11.909 10.343 9.098 7.383 M4.5Ve+M4.5Ve 318 0
6 V* EV Lac Fl* 22 46 49.7311740821 +44 20 02.372223230   11.85 10.26 9.89   M4.0V 777 2

    Equat.    Gal    SGal    Ecl

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2019.10.16-10:10:24

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