Nir Shaviv's Group
Current PhD Students
Calanit Dotan

Calanit
Calanit Dotan
Calanit's PhD research concentrates on the development of super-Eddington models for high rate accretion disks. In such systems, it is not a priori clear whether the accretion energy will be mostly radiated, or accreted, whether the mass loss will be significant or not, or even whether the geometry of the accretion system is going to be disk-like (such as the classical picture) or quasi-spherical. The analysis is carried out given our understanding of radiation pressure dominated systems, which can overshine the Eddington limit and accrelerate a strong wind.

Current M.Sc.
Student
Amir Leshem


Amir Leshem
Using the Hipparcos Star catalogue, Amir Leshem reconstructs the characteristics of the star formation in the Milky Way. Unlike previous analyses, this one includes the initial mass function, the star formation rate history, as well as the metalicity distribution. From this analysis, different periods of high and low star formation activity are evident. Hopefully, the data will also allow finding systematic behavior of the initial mass function with age and metalicity.

Amir Mihaelis


Amir Mihaelis
Amir Mihaelis is developing a numerical radiative transfer module to simulate radiative transfer in any given disordered medium, using a post-diffusive gray approximation. The goal is to have a module which is fast enough to be implementable as part of a hydrodynamic simulation, on one hand, while on the other, to have a scheme which can capture interesting behavior that the diffusive description is lacking, in particular, in optically thin limit. 

Daphna Peimer


Daphna Peimer
Daphna Peimer studies the behavior of radio frequency waves in the pulsar magnetospheres. In particular, we are interested in finding out how different polarization behaviors (e.g., angle swings, generation of circular polarizations) arise from the birefringent nature of the dispersion relation. This is part of a long term collaboration with Jeremy Heyl at U. of British Columbia, where we study the effects of pulsar magnetospheres on the propagation of light.
Previous M.Sc. Student
Smadar Naoz (2004)


Smadar Naoz
In her master, Smadar Naoz employed a cluster birth place analysis to constrain the pattern speed of the Milky Way spiral arms. It this research, it was nicely demonstrated that the Milky Way has at least two different sets of spiral arms. The outer set has 4 arms, and is rotating at about half the solar rotation speed around the galaxy. The number of arms in the second set is not clear, and it is nearly corotating with the solar system. Smadar and her husband have since moved down to the coastal plains, where the air is cleaner and the weather much better, especially in summer. She is continuing for a PhD at Tel-Aviv university.
Paper submitted to New Astronomy


Calanit Dotan (2005)


Calanit Dotan
For her masters project, Calanit Dotan studied the behavior of super-massive objects. These are hypothetical first generation objects. Because they are so massive they don't actually ignite thermonuclear reactions but instead radiate away their gravitational binding energy. Under the classical picture, these objects are expected to shine very near the Eddington luminosity limit. However, instabilities operating at these luminosities imply instead that a super-Eddington state with a "porous" atmospheres should be reached. Calanit modeled these objects under the super-Eddington picture, and found that thy will not emit a copious amout of ionizing radiation, they will however have a strong wind, but not one that will affect their evolution if nuclear reactions are not ignited. These results are now being summarized for publication.

Comments? Send an e-mail to shaviv@phys.huji.ac.il
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