Program Stars and Stellar Parameters Observations References HIGH TEMPORAL RESOLUTION SPECTROSCOPIC HIGH TEMPORAL RESOLUTION SPECTROSCOPIC OBSERVATIONS OF UV CET TYPE FLARE STARS OBSERVATIONS OF UV CET TYPE FLARE STARS

Pallavicini
2004 IAU XXV th General Assembly, IAU Symposium   unpublished
Table. 1: Stellar parameters of the observed stars: spectral type (SpT), vsin(i) and photometric period (P phot ). The remark is --for single stars, SB for spectroscopic binaries (singled lined (1) and double lined (2)) and T for triple star systems. The number of spectra taken of each star (N) and the minimum and maximum exposure times (T exp ) and signal-to-noise ratios (SN) are also given. The program stars are several UV Cet type flare stars of different spectral type ( Table 1) that have
more » ... able 1) that have been taken from the Pettersen 1991 catalogue. UV Cet type flare stars are late K and M dwarfs in the solar neighbourhood that are known to be characterized by intense flaring activity at X rays, optical, UV and radio wavelengths. Flares from UV Cet type stars present the greatest analogy to the solar case (Pallavicini 1990). Abstract We present the preliminary results of a high temporal resolution spectroscopic monitoring of different flare stars (UV Cet type). The observations were done using the IDS spectrograph at the 2.5 m Isaac Newton Telescope (INT) of the El Roque de los Muchachos Observatory (La Palma, Canary Islands, Spain). Intermediate resolution spectra, including the Balmer series from H β to H 11 as well as the He I λ4026 Å and the Ca II H & K lines, were taken using the R1200B dispersion grating (reciprocal dispersion of 0.48 Å/pixel). The great number of spectra taken each night with high temporal resolution (exposure times as short as 60 s) allows us to analyse the time evolution of the emission lines in order to identify flares. Other variations at different scales have been also observed. A comparison between all the observed stars have been done. Finally, for the strongest flares or changes, we study differences on the behaviour of the lines of interest. The observing run took place during 21-25 March 2003. Spectroscopic observations were taken with the 2.5 m Isaac Newton Telescope (INT) at the El Roque de los Muchachos Observatory (La Palma, Canary Islands, Spain). The Intermediate Dispersion Spectrograph (IDS) was used with the R1200B dispersion grating and the 2148x4200 EEV10a CCD detector. The wavelength range covers from 3510 Å to 5200 Å, including the Balmer lines from H β to H 11 as well as the He I λ4026 Å and the Ca II H & K lines. The reciprocal dispersion is 0.48 Å/pixel and the spectral resolution (FWHM) is ~1.15 Å. All the obtained spectra have been calibrated by using Cu-Ar arcs. In order to obtain the highest possible temporal resolution we have taken spectra with exposure times as short as 60 s for the brightest stars and 360 s for the faintest ones. The observed stars are EQ Vir, DK Leo, CR Dra, DT Vir, CE Boo, VV Lyn, DP Dra, V1054 Oph, AD Leo, BL Lyn and YZ CMi. In Table 1 we list some of the stellar and observational parameters.
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