The Near-Infrared Extinction Law and Limits on the Pre–Main-Sequence Population of the ρ Ophiuchi Dark Cloud

Open Access
Publisher Website
Google Scholar
Abstract
We describe new techniques to measure the near-infrared extinction law and to place limits on the pre–main-sequence stellar population of a dark cloud. We analyze JHK imaging data for the central 1 deg2 of the ρ Ophiuchi cloud core and show that nearly all stars projected onto regions of low CS intensity, ICS ≤ 10 K km s-1, are background stars. Most sources at larger CS intensities lie within cloud material. We use the background stars to derive the slope of the near-IR extinction law, EJ - H/EH - K = 1.57 ± 0.03. This result is consistent with previous extinction laws but has a factor of 2–3 smaller uncertainty. The new ρ Oph extinction law yields strong constraints on the number of previously undiscovered pre–main-sequence stars in the cloud, 46 ± 11, and the number of previously undiscovered young stars with near-IR excesses, 15 ± 4. Neither limit exceeds the number of known pre–main-sequence stars in the cloud, ~100. Thus, current samples of pre–main-sequence stars are reasonably complete for K ≤ 14.

This publication has 57 references indexed in Scilit: