English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Results of the time variability monitoring of the two classical T Tauristars, RU Lup and IM Lup, are presented. Three photometric data sets wereutilised: (1) simultaneous (same field) MOST satellite observations over fourweeks in each of the years 2012 and 2013, (2) multicolour observations at theSAAO in April - May of 2013, (3) archival V-filter ASAS data for nine seasons,2001 - 2009. They were augmented by an analysis of high-resolution,public-domain VLT-UT2 UVES spectra from the years 2000 to 2012. From the MOSTobservations, we infer that irregular light variations of RU Lup are caused bystochastic variability of hot spots induced by unstable accretion. In contrast,the MOST light curves of IM Lup are fairly regular and modulated with a periodof about 7.19 - 7.58 d, which is in accord with ASAS observations showing awell defined 7.247+/-0.026 d periodicity. We propose that this is therotational period of IM Lup and is due to the changing visibility of twoantipodal hot spots created near the stellar magnetic poles during the stableprocess of accretion. Re-analysis of RU Lup high-resolution spectra with theBroadening Function approach reveals signs of a large polar cold spot, which isfairly stable over 13 years. As the star rotates, the spot-induced depressionof intensity in the Broadening Function profiles changes cyclically with period3.71058 d, which was previously found by the spectral cross-correlation method.

Stable and unstable accretion in the classical T Tauri stars IM Lup and RU Lup as observed by MOST