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Proposal Information for 2006A-0348


PI: Bernadette Rodgers, Gemini Observatory, brodgers@gemini.edu
Address: AURA Inc., Colina El Pino s/n, La Serena, Chile

CoI: Jorge Garcia, Gemini Observatory

Title: SMARTS Monitoring for Southern UXOR Stars

Abstract: We request queue time on the CTIO1.3m+ANDICAM to monitor three southern pre-main sequence stars. The goal is to observe optical (B,V) and near-infrared (H,K) variability simultaneously, to 1) look for so- called ``UXOR'' behavior: large optical variability accompanied by a characteristic ``blueing effect'' in B-V at deepest optical minima, and 2) document the simultaneous near-infrared behavior for SED modeling. The most likely explanation for this variability is variable extinction from the circumstellar disk, i.e., ``clumps'', ``flares'' or ``warps'' that occasionally move in front of the star along our line of sight; if this is the case simultaneous measurement of near-infrared emission can help constrain existing models but these data are not currently available. Existing databases are primarily optical light curves of northern hemisphere UXORs as a result of small telescope optical monitoring programs. Our initial sample consists of: KK Oph, an historical UXOR star; NX Pup, a Herbig Ae star that has not been well studied previously; and T Cha, an Fe star that shows some evidence of UXOR behavior, based on very little data. Very few F type young stars are known to exhibit the UXOR phenomenon, so discovery of an additional ``late-type'' UXOR would be very interesting. While the ANDICAM data alone are already quite interesting, its very likely that any detected UXOR behavior will also lead to follow-up spectroscopic observations with other southern hemisphere telescopes.


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