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SUMMARY:Cosmic-rays: a possible explanation for the difference of mean dis
 k sizes in star-forming regions
DTSTART;VALUE=DATE-TIME:20200511T143500Z
DTEND;VALUE=DATE-TIME:20200511T145500Z
DTSTAMP;VALUE=DATE-TIME:20240704T115618Z
UID:indico-contribution-37@meetings.aip.de
DESCRIPTION:Speakers: Michael Küffmeier (Zentrum für Astronomie Heidelbe
 rg (ZAH))\nSurveys of protoplanetary disks in star-forming regions of simi
 lar age revealed \nsignificant variations in average disk mass between som
 e regions. Disks in the Orion Nebular Cluster (ONC) and Corona Australis (
 CrA) are on average a factor of a few smaller than disks observed in Lupus
 \, Taurus\, Chamaeleon I or Ophiuchus. We aim for an understanding of the 
 physical mechanism behind this spread by testing the influence of cosmic-r
 ay ionization rates on the formation process of protoplanetary disks. We r
 un non-ideal magnetohydrodynamical protostellar collapse simulations assum
 ing different cosmic-ray ionization rates. We compute the resitivities for
  ambipolar diffusion and Ohmic dissipation with a chemical network. Consis
 tent with previous results\, our models demonstrate that a higher cosmic-r
 ay ionization rate leads to stronger magnetic braking\, and hence to the f
 ormation of smaller disks. Considering recent findings that protostars act
  as forges of comsic rays\, we show that a high average cosmic-ray ionizat
 ion rate in \nstar-forming regions like the ONC or CrA can explain the det
 ection of smaller disks in these regions. Our results show that on average
  a higher cosmic-ray ionization rate leads to the formation of smaller dis
 ks. Therefore\, smaller disks in regions of similar age can be the consequ
 ence of different levels of ionization\, and may not exclusively be caused
  by disk truncation via external photoevaporation. We strongly encourage o
 bservations that allow measuring the cosmic-ray ionization degrees in diff
 erent star-forming regions to test our hypothesis.\n\nhttps://meetings.aip
 .de/event/1/contributions/37/
LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall
URL:https://meetings.aip.de/event/1/contributions/37/
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