STEFAN W. MOCHNACKI


BRITE Images

First BRITE Prototype tracked images download from HERE.


Binary Stars

Paper presented in Slovakia, July 2011.

Application of the GDDSYN Method in the Era of KEPLER, CoRoT, MOST and BRITE


Teaching Stuff

  • AST 325(H)/326(Y) On-line materials (click here)

    M34 observations taken by me (click here)


    Useful old DDO pages


  • See weather here. or here.

  • Data on the DDO instruments, needed for reductions here.



  • Automated Small Telescopes Links HERE

  • Digital Setting Circles
  • Dave Ek's Digital Setting Circles Project Home Page

    Nova Astronomics: Dave Lane at St. Mary's, Halifax. Home , and Information , with sales also at Kendrick's in Toronto.

    Specs for Argo Navis

    Digital Setting Circles for Amateur Telescopes (good review).

    AWR (Heidenhahn) (more professional systems).

    Software-Guided Telescopes (Software Bisque review) , with more here.

    Software-Guided Telescopes (Jim'Mobile catalog)

    Using a serial mouse chip to interface to a shaft encoder

    DAN'S "CANNED MOUSE" PAGE

    Starry Night planetarium and telrescope control user interface.

    Sidereal Technology (drive system).


  • THE BRITE CMOS report is here in PostScript form.
  • And here it's in PDF form.

    Computer Stuff

  • Computing-related materials are HERE.

  • Research Stuff

    Programmes

  • Accurate Integrations of the Roche Model NX = number of X divisions (typ. 150 or 300), NTHETA = number of theta values (typ. 52), F = fill-out ( 1 = inner contact, 2 = outer), Q = mass ratio ( 0 - 1).

    Papers

  • A Spectroscopic Survey of a Sample of Active M Dwarfs. (Tarred, gzipped Latex source)
  • Postscript
  • Table 1, Postscript. (Long table)
  • Paper in PDF form.

    New directions in the study of close binary evolution.

    The recent explosion in the number of known short-period binaries is a by-product of projects such as MACHO, OGLE, HIPPARCOS and various CCD surveys of galactic and globular clusters. Such binaries are even more numerous than previously thought. Understanding the evolution of these binaries is essential to understanding the evolution of stellar populations, and ultimately knowing the age of the Universe and its history.

    My research is aimed at understanding the evolution of binary stars. In the past few years, with my student Paul Hendry I concentrated on mapping surface brightness distributions of a few stars to study magnetic activity, which in turn leads to braking and angular momentum loss. Spots make it difficult to obtain fundamental parameters unless the spot distribution is determined. However, I believe that for the next few years it will be more productive to study many systems extensively rather than a few systems intensively, given the vast numbers of newly discovered binaries from the above-mentioned surveys. This means using cross-correlation methods to obtain Doppler profiles and hence radial velocity curves. The distribution of mass ratios so obtained tests the evolutionary models. A fundamental issue I want to resolve is whether contact binaries lose angular momentum in hundreds of megayears, or over several gigayears.

    The availability of a good spectrograph and CCD combination on the DDO 1.9 metre telescope provides an exciting opportunity to obtain fundamental data for many newly-discovered binary stars in the next few years. I shall continue to observe many contact and near contact short-period binaries to obtain mass ratios; in many cases all physical parameters can be determined when combined with photometry. An essential aspect is the involvement of students as part of their training in our undergraduate and graduate programmes. I shall continue developing methods for modelling the evolution of close binaries, particularly contact systems. The data I obtain observationally will be used directly to test the evolutionary models.


    Systematic Photometric and Spectroscopic Studies of Variable Stars

    The use of automated telescopes with CCD detectors is producing systematic catalogues of variable stars in a number of regimes: the small-telescope ASAS, HAT and ROTSE wide-angle surveys are finding bright variables (as faint as V=13-14) over the entire sky, while larger telescopes are finding large numbers of variables down to 20th magnitude (or fainter) as by-products of relatively small field searches for micro-lensing events, occultations by extra-solar planets and near-earth asteroids. However, there is a surprising lack of data for variable objects in galactic clusters, and for objects in the solar neighbourhood. The aim of this project is to begin a systematic photometric survey of galactic clusters to find variable objects, and to then to follow up with synoptic spectroscopic observations of these objects. I will also observe nearby late-type stars to obtain rotation periods. The magnitude range V=13-17 is too faint for the all-sky surveys, but too bright, too wide and often too time-extended for large- telescope surveys. We now have the ideal instrumentation to undertake such a survey in Toronto.

    The purpose of finding and studying such variables is to understand the formation and evolution of stars, in clusters and in the solar neighbourhood. In addition to obvious and useful results such as better distance determinations, the discovery and study of all variable stars in clusters provides powerful constraints on the ages, chemical abundances and formation scenarios of clusters (and hence of all stars). Conversely, clusters provide constraints on the study of mechanisms such as angular momentum loss in the variable stars, both single and binary.

    With the direct participation of students in our undergraduate and graduate programmes, I shall use the newly-automated Scarborough-based 12-inch Questar telescope equipped with 1024x1024 SITe-chip CCD camera to systematically search galactic clusters for variable stars. This will allow our students to learn the same sort of techniques as used on large telescopes, applied to interesting scientific questions. Spectroscopy of brighter objects will be undertaken with the newly-upgraded 16-inch telescope, and on fainter objects with the 74-inch telescope with its new CCD detector. Under my leadership, the University of Toronto has invested $100,000 in upgrading the undergraduate observatory. Our recently-completed survey of M dwarfs shows the effectiveness of this approach heavily involving students. The effectiveness of the 74-inch telescope has also been demonstrated in a series of recent papers on short-period binaries discovered by HIPPARCOS.

    This project will serve as the starting point for two initiatives:

    (a) to put together a "Toronto Telescope" proposal, for an automated imaging telescope of moderate size at a good site, to be remotely accessible by a number of partner groups in Toronto, and

    (b) to design, propose and obtain funding for a highly-efficient and stable medium-resolution spectrograph with excellent sky subtraction properties, for use on our 74-inch telescope at DDO and on the Magellan 6.5 metre telescopes of Las Campanas Observatory, which we have access to.


    Personal Items

  • Some personal images and accounts.

  • A picture of me

    Comments? Contact: stefan@crux.astro.utoronto.ca

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