Analysis of AAVSO Visual Measurements of T Tauri Variable
Stars
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John R. Percy
Rohan Palaniappan
Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON,
M5S 3H4, Canada
Presented at the 95th Spring Meeting of the AAVSO, May 6, 2006; received August 31, 2006,
revised December 1, 2006, accepted December 1, 2006
Abstract
T Tauri stars are stars in the final stages of birth, in which accretion
from a circumstellar disc of gas and dust is still taking place. By some definitions,
T Tauri stars include only GKM types; in this paper, we include higher-mass pre-
main-sequence variables as well. AAVSO observers have made tens of thousands
of visual measurements of T Tauri stars, but most of the measurements were never
validated because their scientific value was not clear. We have used Fourier and
self-correlation techniques to analyze AAVSO visual measurements of eleven T
Tauri stars, namely AB Aur, RW Aur, SV Cep, R CrA, S CrA, RY Lup, R Mon,
UX Tau, BP Tau, DL Tau, and WW Vul. We have compared the results to those
obtained from long-term CCD measurements of the same stars. Using our methods
of analysis, it is possible to detect periods, even if the amplitude is only a few
hundredths of a magnitude, or to set upper limits, as small as 0.01 magnitude, on
any periodic component to the variability. For each star, periodic or not, we have
determined the variability "profile"--the relation between time scale and amount
of variability. We conclude that the AAVSO visual measurements of T Tauri stars
have definite scientific value. It would therefore be desirable to validate the visual
measurements of other T Tauri stars.
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