Near-IR Non-Detection of the Class 0 Protostellar Outburst HOPS 383
ATel #9969; William J. Fischer (NASA/GSFC), Lynne Hillenbrand (Caltech)
on 17 Jan 2017; 18:42 UT
Credential Certification: William Fischer (firstname.lastname@example.org)
Subjects: Infra-Red, Variables, Young Stellar Object
HOPS 383 is the first Class 0 protostar known to undergo a luminosity outburst (Safron et al. 2015, ApJL, 800, L5). On 2015 December 30.44, we imaged a 5' field centered on HOPS 383 with the MOSFIRE instrument on Keck I. We obtained 18 images of 1.45 s at Ks, 9 images of 8.73 s at H, and 9 images of 18.9 s at J. Total integration times were thus 26.2 s, 78.6 s, and 170 s at Ks, H, and J, respectively.
The HOPS 383 point source previously detected at mid-IR and longer wavelengths was not detected in our near-IR imaging. We calibrated the Keck images with the catalog of Meingast et al. (2016, A&A, 587, 153) and find that the three-sigma detection limits for the point source are 23.1 mag at J, 21.8 mag at H, and 20.4 mag at Ks.
Furthermore, we did not detect the wispy extended emission seen within 15" of the source in the KPNO/NEWFIRM Ks image of 2009 November 25, presented in Safron et al. (2015).
Safron et al. also presented the 3.6 to 870 μm SED of HOPS 383, constructed from data obtained between 2008 and 2011. A radiative transfer model fit to these data predicted that the J, H, and Ks fluxes of this source would be due to scattered light. Inside a 4" radius, they predicted flux densities of 1.87, 37.2, and 282 μJy, respectively. In our MOSFIRE images we find three-sigma detection limits of 2.91, 4.21, and 19.4 μJy.
If the model fit accurately represents the near-IR flux densities of HOPS 383 between 2008 and 2011, then our non-detections at H and Ks represent a decline in the flux densities at these wavelengths by factors of at least 8.8 and 14.5. The physical cause could be a decline in the accretion luminosity of the source by about an order of magnitude, depending on how closely these flux densities trace the accretion luminosity. Alternatively, the declines in flux density could be due to an increase in the extinction at Ks by at least 2.9 mag.