The UX Ori type stars and related topics

The 2-nd international Workshop

The UX Ori type stars and related topics

St. Petersburg, September 30 – October 4, 2019

The UX Ori type stars (or UXORs) are the photometrically most active young objects, predominantly Herbig Ae stars. They demonstrate aperiodic algol-like minima with amplitudes up to ∆V ∼ 2-3 mag and duration from a few days to a few weeks. The brightness variations are accompanied by changes in color, linear polarization and spectra. The most natural explanation of the observed phenomena is a model of variable circumstellar (CS) extinction taking into account scattered radiation from the CS disks. The source of the variable CS extinction is the perturbations in the innermost regions of the CS disks. Therefore the photometric behavior of UXORs is an important, and in some respects unique source of information about the dynamical state of these regions. In recent years extinction events on different timescales have been observed in several T Tauri stars. An important step in the study of such objects was made with the help of photometric observations from space: the CoRoT and Kepler missions. They have shown that the small-amplitude extinction events (dips) of different types (periodic or aperiodic) have been frequently observed in T Tauri stars. In this case the main source of the variable extinction are the dusty disk wind and the region of interaction of CS disk with the stellar magnetosphere. The goal of our workshop is to discuss the observational properties of UXORs and related objects in the light of new theoretical models.

The main topics are:

  • Photometry, polarimetry and spectroscopy of UXOrs
  • Infrared activity of UXOrs and related objects
  • The circumstellar disks, disk winds and the nearest environment of young stars
  • Shadows on the disks, the disks in polarized light
  • Hydrodynamic processes in protoplanetary disks, periodic perturbations and protoplanet formation
  • The UXOr phenomena in T Tauri stars, connection with the AA Tau variables and dippers
  • The evolutionary trends of the UXORs activity

Invited speakers:

Megan Ansdell, Center for Integrative Planetary Science, University of California at Berkeley, Berkeley, USA
TatjanaDemidova, CrAO, Russia
GoestaGahm, Department of Astronomy, AlbaNova University Center, Stockholm University, Sweden
Antonio Garufi, OA Arcetri, INAF, Italy
Stefano Facchini, Max-Planck-InstitutfürExtraterrestrischePhysik, Garching, Germany
Catrina Hamilton-Drager, Department of Physics and Astronomy, Dickinson College, USA
Alexander Kreplin, University of Exeter, United Kingdom
Rebeca Garcia Lopez, DIAS, University of Dublin, Ireland
Ignacio Mendigutia, Centro de Astrobiología (CSIC-INTA), Departamento de Astrofísica, ESA-ESAC
Benjamin Montesinos, UnidadAsociadaAstroUAM-CSIC, Spain
Peter Petrov, CrAO, Russia
Ilya Potravnov, ISTP, Russia
Timo Prusti, Directorate of Science, ESTEC–ESA, Netherlands
Jorick Vink, Armagh Observatory and Planetarium, United Kingdom
Eduard Vorobyev, University of Vienna, Southern Federal University
Claudio Zanni, INAF - Osservatorio Astrofisico di Torino, Italy


Silvia Alencar
Jerome Bouvier
Vladimir Grinin (co-chair)
Sergej Lamzin
Geoffroy Lesur
Agnes Kospal
Antonella Natta
Rene Oudmaijer
Alla Rostopchina-Shakovskaya (co-chair)
Evgeni Semkov


D. Baklanova
O. Barsunova
T. Demidova
D. Dmitriev
T. Ermolaeva
L. Tambovtseva