Measuring Accretion Variability with H I Pfund β

We present multi-epoch accretion rates for 5 transitional disks observed as part of the NIRSPEC and CRIRES surveys of CO emission in circumstellar disks. Accretion rates are derived from Pfund β line flux using the relation outlined in Salyk et al. (in preparation). We find that the highest levels of variability we observe are less than ± 0.50 dex, suggesting that even the most variable objects in our sample exhibit fairly typical accretion variability. In the case of TW Hya, we find that HI Pfund β emission is uncorrelated with both CO fundamental emission and veiling estimates. Further investigation of the association (or lack thereof) between Pfund β and CO fundamental emission can be useful for placing strong constraints on the origin of accretion variability in protoplanetary disks. Brown was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program and the Department of Defense ASSURE program through Scientific Program Order No. 13 (AST-0754223) of the Cooperative Agreement No. AST-0132798 between the Association of Universities for Research in Astronomy (AURA) and the NSF.