Aykut Özdönmez

TÜBİTAK National Observatory (TUG), 07058, Akdeniz University Campus, Antalya, Turkey. mail@aykutozdonmez.me

I recently begin a postdoctoral position at TÜBİTAK National Observatory. I will work photometric and spectroscopic evolution of classical and recurrent novae to deeper understanding the structure and organisation of these systems using the good quality data from small-medium sized telescopes. I am also interested to take part in observational studies on AGNs, supernovae, and the target of opportunity observations...

Throughout my post-graduate studies, my research has been focused mainly on understanding the structure and the nature of cataclysmic variables/novae as well as on their formation and evolution in the Milky Way. Therefore, I developed new approaches to obtain their distances, which is critical to determine astrophysical parameters of any object, and investigated the spatial evolution of these systems in the Galaxy. As a researcher who works intensely on data analysis, I have a number of different projects that make use of large datasets such as 2MASS, WISE, VISTA VVV, GAIA, etc.

My pure interest towards astronomy lead me to have experience on ground based telescopes and in data analyzing. I am always willing to learn new computational techniques and tools that provide me to use various programming languages e.g. Python, Sql, IRAF, and various softwares. Besides, I can easily apply my knowledge in analytical and statistical methods (e.g. applied mathematics, Bayesian approach, Markov chain) to any programming code.

Grants & Awards

Researh Experience

Researcher

  • P.I: Assoc. Prof. Tolga, GÜVER
  • Project no: 114F271

  • The realistic distances are critical to understanding the structure and organization of the objects, while the inverse-square dependency of the luminosities and energies on the distances means that any physical model must have good distances. In project related to my PhD thesis, I developed a software containing multi-process algorithms to derive reddening-distance relations from the location of red clump stars on the colour magnitude diagrams, and to calculate the distances of almost all known Galactic novae. My colleagues and me have provided list of derived distances with other important parameters in a website containing a software with a web GUI by use of mysql, php and python to query a nova in catalogue and to re-calculate distance or interstellar reddening for a nova. Using the novae in the catalogue, I investigated the existence of the MMRD relation that have long been questioned and has often been used to calculate absolute magnitudes. Furthermore, I analyzed the spatial distribution of these systems as a function of their spectral and speed class, as well as Galactic model parameters from outburst space density distributions using different samples based on the distance measurement methods. In addition, the nova rate of the Galactic disk was also calculated. Since nova explosions contribute to the enrichment of the interstellar medium and to chemical evolution of the Galaxy, the nova rate is essential for Galactic chemical evolution models.

    Visited at Instituto de Astrofisica de Canarias in La Laguna as a researcher for 1 week.

    Aug 2014 - Aug 2016

    Researcher

    Scientific & Technological Research Projects Funding Program of TUBITAK
    "Angular Momentum and Orbit Evolution of Binary Stars"
  • P.I: Prof. Faruk SOYDUGAN
  • Project no: 111T224

  • I involve in the project to work on a part of whole research. In project, I worked on the kinematical properties of CVs to understand their formation and evolution in the Galaxy by calculating their space velocities, Galactical orbits, and ages according to their population types and orbital periods.

    Mar 2014 - Aug 2014

    Researcher

    Short Term R&D Funding Program of TUBITAK
    "Galactic Model Parameters of Cataclysmic Variables"
  • P.I: Prof. Selçuk BİLİR
  • Project no: 111T224

  • The spatial distributions and kinematical analysis are important to test evolutionary scenarios and their predictions, as the data obtained from stellar statistics must be in agreement with the proposed evolutionary schemes. To determine the spatial distribution, distance measurements calculated from systematic method are needed. Thus, we derived a period-luminosity-colours (PLCs) relation for the cataclysmic variables (CVs) whose periods and infrared colors are available. The distances calculated from the PLCs relation led me to investigate Galactic model parameters such as scale heights, local space densities and luminosity functions of the CVs and their subclasses in terms of the orbital period in the project related to my MSc. Besides, I used a Monte Carlo model in order to investigate how the thick-disk CVs in the Solar neighborhood affect the Galactic model parameters. Our analysis shows that the scaleheight of CVs is increasing towards shorter periods while space density is decreasing, although selection effects for the periods shorter than 2.25 h dramatically decrease the scaleheight. Moreover, we compared luminosity function of white dwarfs with that of CVs in the study.

    Feb 2013 - Feb 2014

    Observation Experience

    Allocations of Telescope Time

    Tubitak National Observatory, RTT150

    PI: "Optical and near-IR spectrophotometric evolution of classical and recurrent novae"

    4 days in 2018B
    Istanbul University Observatory, IST60

    CoI: "Monitoring the multiwavelength variability of X-ray sources"
    (PI: T. Güver)

    3d each month, 2018
    Tubitak National Observatory, RTT150

    PI: "Interstellar Reddening Measurements of Galactic Novae"

    1 days in 2016A
    3 days in 2015B
    Istanbul University Observatory, IST60

    CoI: "Monitoring transit of the selected Exoplanets"
    (PI: T. Ak)

    7 days in 2013
    Istanbul University Observatory, IST60

    CoI: "Monitoring transit of the Cataclysmic variables"
    (PI: T. Ak)

    2012 - 2014
    60 days

    Observing Experience

    Russian Turkish Telescope (RTT150), 1.5m

    Spectroscopic follow-up of Galactic novae


    4 days in 2018B
    100cm telescope of TUG (T100)

    UBV photometry of open cluster, NGC 6819 (as a co-observer)


    1 day, 2015
    60cm telescope of Istanbul University (IST60)
  • Photometric follow-up of blazars
  • Photometric follow-up of cataclysmic variables
  • Photometric follow-up of exoplanets

  • 3 days, 2018
    40 days, 2012-2014
    5 days, 2013

    Meetings, Conferences & Workshops

    Talks & Posters

  • The 4th Azarquiel School of Astronomy: a Bridge between East and West (summer school), Portopalo di Capo Passero-Syracuse, Italy, Contributed talk (as student).
  • 11 - 16 June 2017
  • 41st COSPAR Scientific Assembly, at the Istanbul Congress Center (ICC), Turkey, Contributed and poster presentation accepted, but the entire conference was canceled.
  • 30 July - 7 Agu 2016
  • XIX. National Astronomy Meeting, Middle East Technical University, Ankara, Turkey, given talk.
  • 2 - 6 Feb 2016
  • XVIII. National Astronomy Meeting, Inönü University, Malatya, Turkey, poster presentation.
  • 27 Aug-1 Sep 2012

    General Participant

  • Seminar series on Compact Stars and Gamma-Ray Bursts, Istanbul University, Istanbul, Turkey.
  • 13 Feb - 18 May 2017
  • Science with Telescopes in Turkey, Istanbul University, Istanbul, Turkey (also was in local organization).
  • 14 - 15 May 2012
  • Science with Small Telescopes Workshop, Istanbul University, Istanbul, Turkey (also was in local organization)
  • 9 - 10 May 2013
  • Hakkı Ögelman Physics Summer School, Science Academy in Beşiktaş, Istanbul, Turkey
  • 9 - 13 July 2012

    Skills

    Programming Languages & Tools
    Practical Techniques

    Public Outreach

  • Led or participated in discussion meetings on leading studies both for under- and graduated students, Istanbul University, Turkey
  • 2012 - 2018
  • Led or participated in public stargazing events, both naked eye and small telescopes, Istanbul University, Turkey
  • 2011 - 2018
  • Given lectures on astrophotography as well as training in dark room, and organized excursions and exhibitions as a member of board in photography club in Istanbul University, Turkey
  • 2006 - 2010

    Research Interests

  • Cataclysmic Variables: Novae; Supernovae
  • Stellar population in the Milky way
  • The Galactic spatial distribution of peculiar types of stellar objects
  • Observational and computational astronomy

  • Interests

    Apart from being a researcher, I enjoy most of my time being outdoors. During the warmer months, I enjoy camping, trekking and swimming. I always look for opportunity to travel abroad and sightseeing. Photography is one of my passion. I enjoy stargazing for long time, and photographing star trailers. Taking pictures for no one other than myself is highly rewarding, soul filling, and fun!

    When forced indoors, I follow a number of sci-fi and fantasy genre movies and television shows, and spend my time playing computer games.



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    Publication List

    I have 5 referred publications in international journals, 3 of which are first author. My Hirsch index is 4; the total number of citations is 24 (sources: NASA/ADS)

  • Özdönmez A., Ergün, E., Güver, T., Ak, T., 2018, "A new catalogue of Galactic novae: investigation of the MMRD relation and spatial distribution", Monthly Notices of the Royal Astronomical Society, Volume 476, Issue 3, p.4162-4186
    doi: 10.1093/mnras/sty432
  • Özdönmez, A., Güver, T., Cabrera-Lavers, A., Ak, T., 2016, "The Distances of the Galactic Novae", Monthly Notices of the Royal Astronomical Society, Volume 461, Issue 2, p.1177-1201.
    doi: 10.1093/mnras/stw1362
  • Seeliger, M., and 47 co-author, 2015, "Ground-based transit observations of the HAT-P-18, HAT-P-19, HAT-P-27/WASP40 and WASP-21 systems", Monthly Notices of the Royal Astronomical Society, Volume 451, Issue 4, p.4060--4072.
    doi: 10.1093/mnras/stv1187
  • Ak, T., Bilir, S., Özdönmez, A., Soydugan, F., Soydugan, E., Püsküllü, Ç., Ak, S., Eker, Z., 2015, "The Galactic kinematics of cataclysmic variables", Astrophysics and Space Science, Volume 357, Issue 1, article id.72 14pp.
    doi: 10.1007/s10509-015-2245-3
  • Özdönmez, A., Ak, T., and Bilir, S., 2015, "Galactic model parameters of cataclysmic variables: Results from a new absolute magnitude calibration with 2MASS and WISE", New Astronomy, Volume, 34, p.234-244.
    doi: 10.1016/j.newast.2014.07.012
  • Websites & Softwares

    Galactic Novae Catalogue
    We compiled a new catalogue of Galactic novae for a lightcurve parameters & distance limited sample. The catalogue contains nearly all important parameters as their light curve parameters (amplitude; Amp, max magnitude at outburst; Vmax, decline times; t2,3), light curve shape, spectra, and recurrence classifications, FWHM Hα, orbital periods, distances and interstellar reddening estimates. For the novae in the catalogue, all reddening estimations are collected from literature and the distances were obtained from expansion/trigonometric parallaxes, or from reddening-distance relations in Özdönmez et al. (2016) are included. Each individual nova webpage contains the reddening - distance relations -if it is available- that leads to re-calculate either distance or interstellar reddening for a given value as in Özdönmez et al. (2016). The website contain a main table and a sql query to search novae systems. Additionally, all references and descriptions for parameters are given in the website. Recently, the catalogue was updated with data from GAIA DR2.Using Gaia parallaxes, the distances were calculated using both uniform and exponantional density functions as described in Luri et al. (2018) and Bailer-Jones et al. (2018)