ORIENT contraints added for both binary targets (to satisfy PSA protection rules for NUV/BOA target acquisition). 1986327589 ----- Attempting Submission 1 (Thu Jul 08 17:56:50 GMT 2021) ----- HST Phase II Proposal 16787 successfully submitted. Receipt: # 16787-1 ----- Attempting Submission 2 (Thu Jul 15 17:54:38 GMT 2021) ----- Cycles and the Seven Dwarfs Somewhat erratic, unpredictable long-term starspot cycles of late-type stars are relevant for understanding the Sun's analogous high-energy modulations, in turn crucial to Earth-impacting "Space Weather" (SW). Similarly, stellar SW counterparts can have equivalent, or more severe, adverse effects on their exoplanets. The solar decadal oscillations are symptomatic of a deep-seated magnetic pump -- the Dynamo -- whose internal workings remain elusive. Key question: is Sun's 11-year cycle normal, or instead a transition state? A 3-year addition to earlier long-term joint Chandra/HST programs (previously involving Alpha Cen [G2V+K1V] and Procyon [F5IV]), will be carried out for two new targets, the nearby binaries Xi Bootis (G8V+K4) and 70 Ophiuchi (K0V+K5V). The HST part of the program will measure FUV subcoronal (T~100,000 K) emission lines, like Si IV 140 nm, C IV 155 nm, and density-sensitive O IV 140 nm, as well as important chromospheric (T~10,000 K) features, like O I 130 nm, C II 133 nm, and C I 165 nm, in both pairs of stars, with one COS visit per system each year. Analyses of these emissions, including dynamical information encoded in Doppler shifts and distortions of the line shapes, can provide insight concerning the thermal/pressure structure of the anomalously hot outer layers of these stars; and how these structural properties change with the ebb and flow of a magnetic activity cycle. **Impact of Reduced Gyro Mode** ------------------------------------------------- The two targets, Xi Boo and 70 Oph, would be minimally affected by RGM, because there is only a minor orientation constraint on the observations (having to do with protecting the PSA for the NUV/BOA target acquisition). Further, the Visits are only 2 orbits, minimizing the possibility of re-acquisition failures. However, if target acquisition times are increased by RGM, then one or more of the exposures would have to be shortened. This can be done with minimal loss of science. ------------------------------------------------- Phase II Observing Description (for normal 3-gyro operations) Observational goal is to obtain FUV moderate-resolution spectra of both components of Xi Boo and 70 Oph using Cosmic Origins Spectrograph (COS) . The primaries, Xi Boo A and 70 Oph A, are nearly identical in FUV flux levels, about a tenth of well-studied (by STIS) Alpha Cen A. Normally, high-sensitivity COS would be off-limits for these primaries, because their strong Lyman-alpha features would violate FUV detector bright limits. However, the COS G130M-1222 setting places Lyman-alpha in the gap between detector sides A and B, so can be used for cool stars, as long as their other strong emissions (e.g., C II 133 nm) are "safe" (as is the case for Xi Boo A and 70 Oph A). When combined with COS G160M-1533, the spectral range 107-171 nm can be covered, with only two small gaps: 120.7-122.3 nm (Lyman-alpha) and 151.5-153.3 nm (devoid of important lines). COS's 15 km/s resolution is fully adequate for the relatively broad FUV emission features of these cool stars, especially the "hot" lines like Si III 120.6 nm (T~30,000 K), Si IV 139.3 nm (80,000 K), and C IV 154.8 nm (100,000 K). The COS FUV channel is so sensitive that a mere 1000 s exposure obtains S/N~100 (line peak) at Si III, 80 at Si IV, and 65 at C IV, for both primary stars. Each grating setting requires 4 "FP-Splits" to mitigate fixed pattern noise. The pair of FUV settings plus FP-SPLITs can be done in a single orbit for the primary of each system, including the initial Guide Star and NUV imaging target acquisitions. At the beginning of the second orbit, the secondary star would be centered by a small offset manuever from the primary, given the accurate orbital ephemeris. The same dual-setting FUV sequence then would be carried out, extending over the remaining unocculted part of the second orbit. The COS visits would be once a year for each system (4 HST orbits per year, total): experience with Alpha Cen AB has shown that the FUV variability, while significant, is not as pronounced as that of the X-rays (which are observed twice a year for each system). Helpfully, key coronal forbidden lines Fe XII 134.9 nm (T~2 MK) and Fe XXI 135.4 nm (10 MK) are available in the FUV to assess the stellar coronal states at the times of the COS pointings. For this reason, the HST and Chandra observations need not be simultaneous. In fact, it is better to have them separated, since the FUV coronal forbidden lines would then provide an additional point on the high-energy timeline. Given the very deep COS exposures proposed here (especially at 134.9 nm and 135.4 nm, which receive double coverage in the 2 nm overlap between G130M and G160M), these coronal forbidden lines should be easily detectable in the primary stars (based on previous STIS experience), and perhaps even in the UV-fainter secondaries. T. Ayres is a highly experienced HST observer, especially with the STIS and COS spectrographs, with dozens of successful programs as PI. Stellar Physics 6 false false false false false false false SUPPORTED STAR CORONA G V-IV NO Target coords for epoch 2000 from SIMBAD, based on Gaia measurements for a mean epoch of 2015.5 corrected for Gaia proper motions XI-BOO-A J2000 J2000 STAR CORONA K V-IV NO Target offset based on orbital model, good for 2021 +/- 1 yr XI-BOO-B J2000 STAR CORONA K V-IV NO Target coords based on Gaia measurements for a mean epoch of 2015.5 (no proper motions cited in DR2); proper motions from Hipparcos. 70-OPH-A J2000 J2000 STAR CORONA K V-IV NO Target offset based on orbital model, good for 2021 +/- 1 yr 70-OPH-B J2000 STIS/FUV-MAMA Spectroscopic No No E140M 1425 STIS/FUV-MAMA Spectroscopic No No E140M 1425 STIS/FUV-MAMA Spectroscopic No No E140M 1425 STIS/FUV-MAMA Spectroscopic No No E140M 1425 STIS/FUV-MAMA Spectroscopic No No E140M 1425 STIS/FUV-MAMA Spectroscopic No No E140M 1425 The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. 1652229432000 177.0 (Tic-Visit :proposal-id 16787 :visit-id "10" :proposal-version -1 :trans-version "20210514" :date "15-Jul-2021 13:54:18.0" :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 157248 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16787 :visit-id "10" :obset-id "10" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16787 :visit-id "10" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2763 :al-overhead-at-end 0 :internal-dur-at-end 38 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3156 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16787 :visit-id "10" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2762 :al-overhead-at-end 0 :internal-dur-at-end 334 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3156 :pcs-gap 0 ) true 2 0 Castelli-Kurucz Models G8V, renormalized to vegamag = 4.68 in filter Johnson/V h_hd131156_uvsum_1m_51163_etc.dat from StarCAT (STIS E140M-1425) h_hd131156_uvsum_1m_51163_etc.dat from StarCAT (STIS E140M-1425) B fluxes scaled by 0.14 from A [h_hd131156_uvsum_1m_51163_etc.dat from StarCAT (STIS E140M-1425)] B fluxes scaled by 0.14 from A [h_hd131156_uvsum_1m_51163_etc.dat from StarCAT (STIS E140M-1425)] The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. 1659094340000 121.7686522605743 (Tic-Visit :proposal-id 16787 :visit-id "11" :proposal-version -1 :trans-version "20210514" :date "15-Jul-2021 13:54:22.0" :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 157248 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16787 :visit-id "11" :obset-id "11" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16787 :visit-id "11" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2749 :al-overhead-at-end 0 :internal-dur-at-end 38 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16787 :visit-id "11" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2750 :al-overhead-at-end 0 :internal-dur-at-end 334 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 2 0 Castelli-Kurucz Models K0V, renormalized to vegamag = 4.22 in filter Johnson/V (from BSC and WDS) (Tic-Visit :proposal-id 16787 :visit-id "11" :proposal-version -1 :trans-version "20210514" :date "15-Jul-2021 13:54:22.0" :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 157248 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16787 :visit-id "11" :obset-id "11" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16787 :visit-id "11" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2749 :al-overhead-at-end 0 :internal-dur-at-end 38 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16787 :visit-id "11" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2750 :al-overhead-at-end 0 :internal-dur-at-end 334 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) false 2 0 Castelli-Kurucz Models K0V, renormalized to vegamag = 4.22 in filter Johnson/V (from BSC and WDS)