Kavli Affiliate: Gregory Herczeg
| Summary:
We present the results of the first high-sensitivity NUV (1800 to 3200 Å) survey of FU Ori objects, using the textitHubble Space Telescope (HST) STIS spectrograph. We compare new low resolution spectra for 6 sources with predictions from accretion disk models and find that all show emission in excess of the disk model spectrum. The physical properties of the NUV emission excess are very consistent among the sample, with a mean luminosity of $10^-1.11 pm 0.4 L_odot$ and temperature of $16400 pm 2600$ K — despite spanning 0.9 dex in $M_*$, 1.3 dex in $dotM$, and 0.7 dex in $L_mathrmacc$. We use the spectra to conclusively rule out the existence of a hot boundary layer in FU Ori accretion disks. We then discuss the source of the excess emission in the context of recent simulations of FU Ori outbursts and boundary layer accretion. The UV spectra also show the often-seen ionC2] 2326 Å multiplet and ionMg2 2796/2803 Å doublet, as well as the unusual ionFe2] 2507/2509 Å doublet, a feature that is not seen in the existing UV spectra of other young stellar objects. We measure and compare the luminosities of these lines in outbursting with those in non-outbursting objects.
| Search Query: arXiv Query: search_query=au:”Herczeg Gregory”&id_list=&start=0&max_results=10
Read More