PI: Arlin Crotts, Columbia University, firstname.lastname@example.org
Address: Department of Astronomy, 550 West 120th St., New York, NY 10027, U.S.A.
Title: SN 1987A's Vacuum UV/Optical Light Echo Evolution
Abstract: We propose to continue a series of observations that for the past 24 years have yielded most of the results concerning the light echoes from SN 1987A, both on interstellar and circumstellar scales. These observations have been conducted every month or two, primarily on the CTIO 0.9-meter (and occasionally Las Campanas 1-meter). We now propose to continue a series of new discoveries; among these we anticipate: 1) mapping of the detailed three-dimensional structure of a large supershell around a massive OB association near 30 Doradus, 2) a determination of where dense dust globules, perhaps the sites of incipient star formation, rest in relation to the large-scale shocks which likely produce them, 3) completion of the three-dimensional map of SN 1987A's circumstellar nebula, 4) help in using echoes from SN 1987A to establish a geometrically-determined distance to the SN and the LMC, and 5) in connection with Galex, a measurement of the vacuum-UV flux emitted by the SN explosion during its first hours, missed in 1987. These results will involve our demonstrated techniques in using echoes to extract the echoes from brighter, constant-flux environments. While we will make use of the recent SuperMACHO data of the same field, these observations are much more wavelength- and time-comprehensive. Of all of these observations, next semester's is most crucial, because Galax is now observing the vacuum-UV, in its last pointings (including bright-star fields like SN 1987A). The UV echo, primarily from shock breakout during the first hours of the SN, never observed elsewhere, has been observed by IUE, UIT and HST to ambiguous result. Galex will have the best combination of wide field and sensitivity to settle this issue. We need ground-based photometry to properly interpret UV data from this once-in-a-lifetime opportunity, and follow-up optical imaging like ours 80 days later is absolutely essential, since it characterizes the clouds at max light which reflect the initial UV pulse.
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