Assigned ID: 127 ----- Attempting Submission 1 (Wed Feb 22 23:31:12 GMT 2012) ----- HST Phase I Proposal 127 (sbw1cos.apt) successfully submitted. ----- Attempting Submission 1 (Thu Jul 05 22:34:46 GMT 2012) ----- We are aware of this. Not necessary for our science goals. We propose to use COS to obtain an FUV spectrum of the B supergiant SBW1, in order to measure this star's wind speed and mass-loss rate. This star is of particular interest because it is surrounded by a ring nebula that closely resembles the triple-ring nebula around SN 1987A. The unusual nebula, combined with the luminosity and spectral type of the star, make SBW1 the closest known Galactic twin of the progenitor of SN 1987A. We recently obtained WFC3 images and STIS spectra of SBW1 that not only verify this close comparison with SN 1987A and elucidate some of the detailed structures in the nebula, but the new HST images also show additional features that we didn't expect. Namely, our HST images and ground-based mid-IR images from Gemini show evidence for a structure interior to the ring that appears to be the terminal shock of the wind interacting with a backflow from the ring. Such structures were predicted to exist around the SN 1987A progenitor based on models for the speed of the expanding blast wave, but they were never actually seen. The reason we want to measure the wind speed and mass-loss rate from the COS spectrum is so that we can test whether or not the terminal wind shock provides a suitable physical explanation for the structure seen in WFC3 and Gemini images. If so, it would significantly alter ideas about the formation of the SN 1987A rings, because it would mean that the B supergiant wind is actually not interacting directly with the outer ring nebula, as proposed based on some hydrodynamic models. The observations in this program will obtain a UV spectrum of the type B1.5 Iab blue supergiant that is the central source of the SBW1 nebula, which is a near twin of the ring nebula around SN 1987A. The purpose is to use UV line diagnoistics to estimate the wind mass-loss rate of the blue supergiant star. Like the progenitor of SN 1987A, there are indications that the wind of this supergiant is rathern weak, and the mass-loss rate has important implications for understanding the shaping of the nebula. The observations will use the G160M grating at central wavelengths of 1577 and 1600 Angstroms. The expected UV flux at these wavelengths is based on extrapolating from the visual magnitudes using the observed spectral type and reddening of the star. HOT STARS 12 false 0.0 0.0 false false false false SUPPORTED STAR B0-B2 III-I This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 COS/FUV Spectroscopic No No G160M 1577 1341515712579 /Users/nathans/Desktop/PROPOSALS/HST-20/PhaseII/OP-cache/sbw1cos_ph2-v01.xml The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12924 :visit-id "01" :proposal-version -1 :trans-version "20120604" :date "05-Jul-2012 12:15:11.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 904720 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12924 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12924 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3158 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3491 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12924 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3269 :al-overhead-at-end 0 :internal-dur-at-end 114 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3491 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12924 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3269 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3491 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12924 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 3269 :al-overhead-at-end 0 :internal-dur-at-end 414 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3491 :pcs-gap 0 ) true 4 0 Target Acq: B0I star Castelli & Kurucz model, V=12.7, E(B-V) = 1.15. F(1550A) = 2x10^{-15} [erg/cm2/s/A]. Spectroscopic observation assumes a flat spectrum normalized to this value (COS.sp.412090).