0 Assigned ID: 564 ----- Attempting Submission 1 (Fri Apr 11 16:26:22 GMT 2014) ----- 0 ----- Attempting Submission 1 (Mon Jul 21 16:25:31 GMT 2014) ----- ----- Attempting Submission 2 (Thu Oct 23 22:17:45 GMT 2014) ----- Probing the extreme wind confinement of the most magnetic O star with COS spectroscopy We propose to obtain phase-resolved UV spectroscopy of the recently discovered magnetic O star NGC 1624-2, which has the strongest magnetic field ever detected in a O-star, by an order of magnitude. We will use the strength and variability of the UV resonance line profiles to diagnose the density, velocity, and ionization structure of NGC 1624-2's enormous magnetosphere that results from entrapment of its stellar wind by its strong, nearly dipolar magnetic field. With this gigantic magnetosphere, NGC 1624-2 represents a new regime of extreme wind confinement that will constrain models of magnetized winds and their surface mass flux properties. A detailed understanding of such winds is necessary to study the rotational braking history of magnetic O-stars, which can shed new light on the fundamental origin of magnetism in massive, hot stars. Our program requires time-critical observations of NGC 1624-2 at two rotational phases, as described below. For each of these observations, we aim to investigate important photospheric, wind, and magnetospheric features such as N V 1239,1243 A, Si IV 1393,1403 A, C IV 1548,1550 AA, N IV 1718 A. NGC 1624-2, with V=11.8, E(B-V)=0.9, will therefore be optimally observed at the COS medium resolution with the G130M (settings 1291, 1327 A) and G160M (1577, 1623 A) gratings for the maximum available, uninterrupted wavelength coverage of 1134 - 1798 A. Two orbits in each of the two visits at high and low states will be required. The coordinates of the target are precise enough to use the ACQ-image. The BOA aperture is used for the acquisition. An exposure of 86 seconds is enough to reach the recommanded SNR of 60. The ephemeris for NGC 1624-2 is JD = 245 5967.0 (+-10) + 157.99 (+-0.94) x E (Wade et al. 2012). A tolerance of +-0.05 cycles around the desired phases leads to periodic observational windows of 2 weeks that are consistent with these constraints. HOT STARS Default false true false false false SUPPORTED STAR OF This object was generated by the targetselector and retrieved from the SIMBAD database. J04403728+5027410 J2000 J2000 COS/FUV Spectroscopic No No G130M 1291 COS/FUV Spectroscopic No No G130M 1327 COS/FUV Spectroscopic No No G160M 1577 COS/FUV Spectroscopic No No G160M 1623 COS/FUV Spectroscopic No No G130M 1291 COS/FUV Spectroscopic No No G130M 1327 COS/FUV Spectroscopic No No G160M 1577 COS/FUV Spectroscopic No No G160M 1623 /Users/vpetit/Astro/HST_APT/OP-cache/Dash2_modified-v01.xml The scheduling data was generated by CASM 22.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 13734 :visit-id "01" :proposal-version -1 :trans-version "20140605" :date "23-Oct-2014 18:00:49.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 365760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13734 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13734 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3063 :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 3409 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13734 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3181 :al-overhead-at-end 0 :internal-dur-at-end 385 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3409 :pcs-gap 0 ) true 2 0 /Users/vpetit/Astro/HST_APT/OP-cache/Dash2_modified-v02.xml The scheduling data was generated by CASM 22.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 13734 :visit-id "02" :proposal-version -1 :trans-version "20140605" :date "23-Oct-2014 18:01:19.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 365760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13734 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13734 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3063 :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 3409 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13734 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3181 :al-overhead-at-end 0 :internal-dur-at-end 385 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3409 :pcs-gap 0 ) true 2 0