TY - JOUR

T1 - Analysis of the historical light curve of the UX Ori star CQ Tau

AU - Shakhovskoj, D. N.

AU - Grinin, V. P.

AU - Rostopchina, A. N.

N1 - Funding Information: We thank N. Ya. Sotnikova and L. V. Tambovtseva for useful discussions of the questions raised in this article and N. Kh. Minikulov for providing the data on photographic observations of CQ Tau published in Ref. 19. This work was partially supported by a grant from the Presidium of the Russian Academy of Sciences on “Nonstationary phenomena in astronomy”, INTAS grant No. 03-51-6311, and NSh grant 1088.2003.2.

PY - 2005/4

Y1 - 2005/4

N2 - An historical light curve for the UX Ori star CQ Tau is constructed for the period from 1939 through 2003. The star's photometric behavior includes a cyclical component with a period of about 21 years. An analysis of the periodogram reveals a shorter cycle with a duration of about 1020 days after this cycle is subtracted. Since the photometric activity of UX Ori type stars is caused by variations in the circumstellar extinction, both of these cycles indicate the existence of large-scale deviations from axial symmetry in the distribution of matter in the circumstellar disk of CQ Tau. The orbiting of these inhomogeneities about the star also causes oscillatory variations in its brightness. An analysis of the color-magnitude diagrams reveals differences in the optical parameters of the circumstellar dust along the line of sight in various phases of the 21-year cycle: absorption by larger particles predominates near the brightness maximum of CQ Tau. This means that the reduced circumstellar extinction in this part of the circumstellar disk is the result of a smaller contribution from small particles; this may be evidence of the onset of a process of coagulation of the dust particles and their conversion into large-scale bodies and planetesimals.

AB - An historical light curve for the UX Ori star CQ Tau is constructed for the period from 1939 through 2003. The star's photometric behavior includes a cyclical component with a period of about 21 years. An analysis of the periodogram reveals a shorter cycle with a duration of about 1020 days after this cycle is subtracted. Since the photometric activity of UX Ori type stars is caused by variations in the circumstellar extinction, both of these cycles indicate the existence of large-scale deviations from axial symmetry in the distribution of matter in the circumstellar disk of CQ Tau. The orbiting of these inhomogeneities about the star also causes oscillatory variations in its brightness. An analysis of the color-magnitude diagrams reveals differences in the optical parameters of the circumstellar dust along the line of sight in various phases of the 21-year cycle: absorption by larger particles predominates near the brightness maximum of CQ Tau. This means that the reduced circumstellar extinction in this part of the circumstellar disk is the result of a smaller contribution from small particles; this may be evidence of the onset of a process of coagulation of the dust particles and their conversion into large-scale bodies and planetesimals.

KW - CQ Tau

KW - Individual

KW - Stars

KW - Variables

UR - http://www.scopus.com/inward/record.url?scp=20844435436&partnerID=8YFLogxK

U2 - 10.1007/s10511-005-0014-7

DO - 10.1007/s10511-005-0014-7

M3 - Review article

AN - SCOPUS:20844435436

VL - 48

SP - 135

EP - 142

JO - Astrophysics

JF - Astrophysics

SN - 0571-7256

IS - 2

ER -