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

RESEARCH TOPICS

• 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