M ODELING OF I NTERACTING B INARY S YSTEMS O. Latković, G. Đurašević, I. Vince & A. Čeki Astronomical Observatory of Belgrade

B INARY STAR RESEARCH IN THE STELLAR PHYSICS GROUP AT AOB Massive binaries Overcontact systems Systems with gas streams and accretion disks Double-periodic variables 2

T HE MODEL OF A CLOSE BINARY SYSTEM 3 Roche model Gravity darkening Irradiation feedback Bright or dark circular spots Accretion disk Trapezoid cross-section Radial temperature distribution Active regions as bright spots

A CTIVE REGIONS ON THE DISK : HOT SPOT AND SPIRAL STRUCTURE The HOT SPOT (hot line) is a representation of the area where the gas stream from the donor impacts the disk around the gainer The BRIGHT SPOTS represent the brightness irregularities that arise from spiral structure 4

V455 C YG : A PECULIAR MASSIVE BINARY WITH AN ACCRETION DISK Spectroscopy Echelle spectrograph attached to 1.25 m telescope (SAI Crimean Observatory) Photometry 60 cm telescope (Maidanak Observatory) 60 cm telescope (SAI Crimean Observatory) System parameters: 5 Monthly Notices of the Royal Astronomical Society Volume 420, Issue 4, pages , 10 FEB 2012 DOI: /j x Volume 420, Issue 4, PrimarySecondaryDisk M[M ʘ ] R [R ʘ ] T [K] Orbital parameters P ORB [d]8.76 a ORB [R ʘ ]48.0 i []78.2

V455 C YG : A PECULIAR MASSIVE BINARY WITH AN ACCRETION DISK Monthly Notices of the Royal Astronomical Society Volume 420, Issue 4, pages , 10 FEB 2012 DOI: /j x Volume 420, Issue 4, 6 PrimarySecondaryDisk M[M ʘ ] R [R ʘ ] T [K] Orbital parameters P ORB [d]8.76 a ORB [R ʘ ]48.0 i []78.2 Spectroscopy Echelle spectrograph attached to 1.25 m telescope (SAI Crimean Observatory) Photometry 60 cm telescope (Maidanak Observatory) 60 cm telescope (SAI Crimean Observatory) System parameters:

V455 C YG : A PECULIAR MASSIVE BINARY WITH AN ACCRETION DISK Monthly Notices of the Royal Astronomical Society Volume 420, Issue 4, pages , 10 FEB 2012 DOI: /j x Volume 420, Issue 4, 7 PrimarySecondaryDisk M[M ʘ ] R [R ʘ ] T [K] Orbital parameters P ORB [d]8.76 a ORB [R ʘ ]48.0 i []78.2 Spectroscopy Echelle spectrograph attached to 1.25 m telescope (SAI Crimean Observatory) Photometry 60 cm telescope (Maidanak Observatory) 60 cm telescope (SAI Crimean Observatory) System parameters:

V455 C YG : A PECULIAR MASSIVE BINARY WITH AN ACCRETION DISK Monthly Notices of the Royal Astronomical Society Volume 420, Issue 4, pages , 10 FEB 2012 DOI: /j x Volume 420, Issue 4, 8 PrimarySecondaryDisk M[M ʘ ] R [R ʘ ] T [K] Orbital parameters P ORB [d]8.76 a ORB [R ʘ ]48.0 i []78.2 Spectroscopy Echelle spectrograph attached to 1.25 m telescope (SAI Crimean Observatory) Photometry 60 cm telescope (Maidanak Observatory) 60 cm telescope (SAI Crimean Observatory) System parameters:

V393 S CO : A DOUBLE - PERIODIC BINARY Observations REM 60 cm telescope (La Silla) ASAS array (Las Campanas) 9 Monthly Notices of the Royal Astronomical Society Volume 421, Issue 1, pages , 9 FEB 2012 DOI: /j x Volume 421, Issue 1, PrimarySecondaryDisk M[M ʘ ] R [R ʘ ] T [K] Orbital parameters P ORB [d]7.71 a ORB [R ʘ ]35.1 i []80.0 P LONG [d]253P LONG /P ORB 33

V393 S CO : A DOUBLE - PERIODIC BINARY Monthly Notices of the Royal Astronomical Society Volume 421, Issue 1, pages , 9 FEB 2012 DOI: /j x Volume 421, Issue 1, 10 Observations REM 60 cm telescope (La Silla) ASAS array (Las Campanas) PrimarySecondaryDisk M[M ʘ ] R [R ʘ ] T [K] Orbital parameters P ORB [d]7.71 a ORB [R ʘ ]35.1 i []80.0 P LONG [d]253P LONG /P ORB 33

AU M ON : ANOTHER DOUBLE - PERIODIC BINARY 11 Monthly Notices of the Royal Astronomical Society Volume 409, Issue 1, pages , 17 AUG 2010 DOI: /j x Volume 409, Issue 1, PrimarySecondaryDisk M[M ʘ ] R [R ʘ ] T [K] Orbital parameters P ORB [d]11.11 a ORB [R ʘ ]42.1 i []80.1 P LONG [d]417P LONG /P ORB 37.5

R ECENT IMPROVEMENTS OF THE MODEL A different geometrical approach Simultaneous fitting of light and radial velocity curves Elliptical orbits Enhanced modeling of accretion disks Modeling of stellar pulsations 12

A DIFFERENT GEOMETRICAL REPRESENTATION Sampling strategy: geodesic grid Uniform sampling of the surface Allows for very fine division 13 Colors represent the temperature distribution Gravity darkening Irradiation feedback

A DIFFERENT GEOMETRICAL REPRESENTATION 14 Detailed modeling of the eclipse using adaptive subdivision

I MPROVED MODELING OF THE ACCRETION DISK Disk shapes Concave and convex disks Toroidal disks Multiple disks / disks with holes Fine surface division Temperature distribution and angular velocity distribution as arbitrary functions 15

M ODELING OF STELLAR PULSATIONS Perturbations are modeled as spherical harmonics and applied to position and temperature Arbitrary number of modes Arbitrary pulsation axis 16 L=4, M=2 L=5, M=5 Superposition

M ODELING OF STELLAR PULSATIONS 17 A single L=10, M=5 mode with exaggerated displacement amplitude

M ODELING OF I NTERACTING B INARY S YSTEMS O. Latković, G. Đurašević, I. Vince & A. Čeki Astronomical Observatory of Belgrade