Orsolya Fehér

Konkoly Observatory, Budapest, Hungary

Momentum Disk Research Group
PI: Ágnes Kóspál

PhD candidate at Eötvös Loránd University, Budapest, Hungary

supervisor: L. Viktor Tóth

Interstellar Material and Early star formation on large and small scales


  • star formation in cold, dense galactic clumps discovered by Planck and mapped by Herschel
    • physical parameters, kinematics and stability from dust continuum and molecular line emission
    • description of star forming activity in clumps (AKARI, WISE)
  • mass accretion and eruption process in FU Orionis-type, low-mass, eruptive young stars
    • millimeter interferometric mapping of the continuum and a number of molecular species/transitions with ALMA, NOEMA, JCMT, APEX
    • tracing the envelope and the envelope/disk interface
    • morphology, kinematics, mass transfer

Galactic Cold Cores research team (Herschel Key Programme, PIs: Mika Juvela, Isabelle Ristorcelli)
TOP-SCOPE project (PI: Tie Liu)
Momentum Disk Research Group (PI: Ágnes Kóspál) + SACCRED ERC project (PI: Ágnes Kóspál)

INitial conditions of star formation

Planck: > 13,000 dense, cold, potentially star forming galactic structures ("clumps")

--> a possibility to study of the earliest phases of SF on a statistical sample

(the nature of the objects, initial conditions, stages, timeline, environmental effects)

Herschel: high resolution and sensitivity FIR maps of individual regions

credit: L. Montier

STructure of Tmc-1

  • dense, filamentary cloud in Taurus
  • part of a bush-like group of Planck objects (Heiles Cloud 2) with complex morphology
  • high S/N and velocity resolution NH3 observations with the Effelsberg telescope as part of our ammonia survey of cold dense regions spanning several years

Fehér et al. 2016, A&A

  • temperature and column density distribution + kinematics --> sub-structures
  • close to equilibrium, chemical and dynamical age different
  • turbulence increased by an outflow in the main ridge

CO survey of Planck objects

  • part of the systematic ground-based molecular emission survey of Planck objects
  • correlation of continuum- and line-based densities, temperatures, determination of stability
  • 35 clumps observed in two CO isotopologues with the Onsala 20m telescope
  • most objects are cold, dense, rare traces of heating
  • continuum- and line-based densities correlate well
  • kinematic distances, stability
  • 2 object groups: close-by, core-sized, low-mass and grav. unbound clumps and massive, parsec-scale clouds farther away

Fehér et al. 2016, A&A

Interferometric view of the envelopes of Fu ori-type stars

  • IRAM/NOEMA merged observations of 8 northern FUors (CO and 2.7 mm continuum)
  • size, mass, kinematics of envelopes
  • process of episodic accretion
  • possible evolutionary sequence
  • detection of "extended envelopes" on a 10,000 AU scale, clumpy structure
  • heated, few 1000 AU envelopes centered on the stars, outflows
  • envelope parameters suggest Class I and II sources - "normal" YSOs in a special state?

Fehér et al. 2017, A&A

Ábrahám, ..., Fehér, ..., 2017, ApJ

MASS Transport around V346 Nor

  • pilot study for our ALMA project on southern FU Ori-type objects
  • CO isotopologues and 1.3 mm continuum with a resolution of ~1" (~700 AU)
  • disk/envelope/outflow cavity mapping, mass, kinematics, morphology
  • compact continuum, extended CO
  • spectro-astrometry: outer pseudo-disk (rotation + infall), inner 350 AU keplerian disk
  • the infall rate from the envelope to the disk is a factor of a few higher than the quiescent accretion rate --> mechanism of eruption

Kóspál, ... Fehér, ..., 2017, ApJ

In progress: AMmonia surveys of the galactic cold ISM

  • Effelsberg observations 2008-2016
  • ~ 40 PGCC mapped NH3(1,1) and (2,2) transitions
    (Tóth, ..., Fehér, ..., in prep)
  • individual objects studies:
    • ​the double core of G163.82-8.44
      (Zahorecz, ..., Fehér, ..., in prep.)
    • the clumps of Heiles Cloud 2
      (Fehér et al. in prep)
  • effects of galactic environment on star forming regions (project initiated)
  • TOP-SCOPE collaboration: diverse list of Planck objects described with measurements of many molecular species and continuum

In progress, planned and interested in:

  • ALMA study of > 10 FU Orionis-type objects
    • CO and continuum mapping to derive physical parameters, see structure and kinematics ​as started with the study of V346 Nor
    • mass infall rate, envelope dispersal process
  • chemical study of FUors with single-dish measurements
    • IRAM, APEX
  • resolving the envelope/disk interface with NOEMA
    • might reach spatial resolutions close to ALMA
    • dynamics of infall
  • structure on even smaller scales: disk morphology and parameters, dust and gas composition and evolution, infrared and optical interferometry, the role and possibilities of RT models
  • connecting the results of star formation studies on different scales and to environmental effects

Specific skills acquired during my research

  • observation and data reduction/analysis experience with several radio telescopes (Effelsberg, Onsala, IRAM, JCMT)
  • practiced utilisation of the GILDAS software for single-dish and interferometric data calibration, reduction and analysis
  • basic understanding and usage of the CASA package, frequent usage of IDL and python
  • writing and planning telescope time proposals as PI and co-I (Effelsberg, IRAM, APEX, ALMA)
  • teaching and tutoring:
    • ​basic astronomy, observational astronomy to BSc students
    • supervision of an MSc student summer projects (2016)
    • supervision of a BSc student project (2017, 1st prize at the Scientific Students' Associations Conference)
    • tutoring of students in our research group (molecular line data reduction and analysis, calculations from Herschel measurements)
  • organizing and participating at several workshops, conferences (talks, posters)
  • organizing weekly scientific "Coffee Breaks" at the institute

contributions to the work of the disk and planet formation imaging group

  • analysis and interpretation of existing data, stating and answering questions, learning and applying new techniques
    • experience with ALMA data and radio interferometry, interest in optical and infrared interferometry
  • proposal, preparation and execution of new observations
  • presenting and publishing results
  • contributing to the planning of new projects
  • teaching and tutoring students
  • outreach

University of Exeter presentation

By Orsolya Fehér

University of Exeter presentation

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