17839( 3) - 16-Aug-2024 11:10:03 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17839 Version: 3 Check-in Time: 16-Aug-2024 11:10:03 STScI Edit Number: 0 Title The Beat Goes On ------------------------------------------------------------------------------------ Type Cycle GO 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Thomas R. Ayres University of Colorado at Boulder Y ------------------------------------------------------------------------------------ Abstract (This is a joint Chandra/HST program: the Chandra proposal abstract follows.) Chandra has been following magnetic heartbeats of late-type stars via high-contrast coronal X-rays. Goal is to provide fundamental observational constraints for contemporary and future studies of the underlying magnetic dynamo, whose internal workings remain elusive. The Sun's high-energy modulations play an important space weather role in our heliosphere, as do stellar counterparts for their exoplanets. A 3-year continuation (joint with HST) is proposed for current cycles targets Xi Boo (G8V+K4) and 70 Oph (K0V+K5V). Key questions: (1) origin of diverging branches in rotational period vs. cycle duration, where Sun sits isolated in the middle, possibly in a transitional state; (2) extent of high-energy variability bias, which can affect interpretations of large surveys. ------------------------------------------------------------------------------------ Observations Description ------------------------ **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 17839( 3) - 16-Aug-2024 11:10:03 - [ 2] 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 time line. 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), the Fe XII coronal forbidden line will be easily detected in the primary stars (based on the previous COS visits), and probably also in the UV-fainter secondaries. ------------------------------------------------------------------------------------ 17839( 3) - 16-Aug-2024 11:10:03 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD-131156A STAR, CORONA, G V-IV RA=14H51M23.3885S +/- 0.2", J2000 V = +1.5 V = +4.68 +/- 0.1 DEC=+19D06'1.62" +/- 0.2" Reference Frame: ICRS Extended: NO Comments: Target coords for epoch 2000 from SIMBAD, based on Gaia measurements for a mean epoch of 2015.5 corrected for Gaia proper motions Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.008995219750282533 -0.0406 0.148 ------------------------------------------------------------------------------------------------------------------------------------ 2 HD-131156B STAR, CORONA, K V-IV RA-OFF=-0.325S, DEC-OFF=+1.58", J2000 V = +2.3 V = +6.82 +/- 0.1 FROM 1 Reference Frame: ICRS Extended: NO Comments: Target offset based on ephemeris from 6th Orbit Catalog, for 2025.5 ------------------------------------------------------------------------------------------------------------------------------------ 3 HD-165341A STAR, CORONA, K V-IV RA=18H05M27.2484S +/- 0.2", J2000 V = -9.7 V = +4.03 +/- 0.1 DEC=+02D30'0.53" +/- 0.2" Reference Frame: ICRS Extended: NO Comments: Target coords for epoch 2000 from SIMBAD, based on Gaia measurements for a mean epoch of 2015.5 corrected for Gaia proper motions Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.013779783511711106 -1.1075 0.1956 ------------------------------------------------------------------------------------------------------------------------------------ 4 HD-165341B STAR, CORONA, K V-IV RA-OFF=+0.400S, DEC-OFF=-3.06", J2000 V = V = +6.07 +/- 0.1 FROM 3 -10.0 Reference Frame: ICRS Extended: NO Comments: Target offset based on ephemeris from 6th Orbit Catalog, for 2025.5 ------------------------------------------------------------------------------------------------------------------------------------ 17839( 3) - 16-Aug-2024 11:10:03 - [ 4] Visit: 10 Visit Requirements: GYRO MODE 1G; ORIENT 130D TO 10 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD-131156A COS/NUV ACQ/IMA BOA MIRRORB 1 11 S (11 GE S) Comments: Castelli-Kurucz Models G8V, renormalized to vegamag = 4.68 in filter Johnson/V ------------------------------------------------------------------------------------------------------------------------------------ 2 HD-131156A COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=2400, FP-POS=ALL, 1 177 S (708 G LIFETIME-POS=LP4 S) Comments: h_hd131156_uvsum_1m_51163_etc.dat from StarCAT (STIS E140M-1425) ------------------------------------------------------------------------------------------------------------------------------------ 3 HD-131156A COS/FUV TIME-TA PSA G160M 1533 BUFFER-TIME=4000, FP-POS=ALL, 1 176 S (704 G LIFETIME-POS=LP4 S) Comments: h_hd131156_uvsum_1m_51163_etc.dat from StarCAT (STIS E140M-1425) ------------------------------------------------------------------------------------------------------------------------------------ 4 HD-131156B COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=9300, FP-POS=ALL, 1 216 S (864 G LIFETIME-POS=LP4 S) Comments: B fluxes scaled by 0.14 from A [h_hd131156_uvsum_1m_51163_etc.dat from StarCAT (STIS E140M-1425)] ------------------------------------------------------------------------------------------------------------------------------------ 5 HD-131156B COS/FUV TIME-TA PSA G160M 1533 BUFFER-TIME=13400, FP-POS=ALL, 1 216 S (864 G LIFETIME-POS=LP4 S) Comments: B fluxes scaled by 0.14 from A [h_hd131156_uvsum_1m_51163_etc.dat from StarCAT (STIS E140M-1425)] ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HD-131156A 1 COS/NUV ACQ/IMA BOA MIRRORB none none none none 1 N/A GE HD-131156A 2 COS/FUV TIME-TA PSA G130M 1222 none none none 1 1 N/A G HD-131156A 2 COS/FUV TIME-TA PSA G130M 1222 none none none 2 1 N/A G HD-131156A 2 COS/FUV TIME-TA PSA G130M 1222 none none none 3 1 N/A G 17839( 3) - 16-Aug-2024 11:10:03 - [ 5] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HD-131156A 2 COS/FUV TIME-TA PSA G130M 1222 none none none 4 1 N/A G HD-131156A 3 COS/FUV TIME-TA PSA G160M 1533 none none none 1 1 N/A G HD-131156A 3 COS/FUV TIME-TA PSA G160M 1533 none none none 2 1 N/A G HD-131156A 3 COS/FUV TIME-TA PSA G160M 1533 none none none 3 1 N/A G HD-131156A 3 COS/FUV TIME-TA PSA G160M 1533 none none none 4 1 N/A G HD-131156B 4 COS/FUV TIME-TA PSA G130M 1222 none none none 1 2 N/A G HD-131156B 4 COS/FUV TIME-TA PSA G130M 1222 none none none 2 2 N/A G HD-131156B 4 COS/FUV TIME-TA PSA G130M 1222 none none none 3 2 N/A G HD-131156B 4 COS/FUV TIME-TA PSA G130M 1222 none none none 4 2 N/A G HD-131156B 5 COS/FUV TIME-TA PSA G160M 1533 none none none 1 2 N/A G HD-131156B 5 COS/FUV TIME-TA PSA G160M 1533 none none none 2 2 N/A G HD-131156B 5 COS/FUV TIME-TA PSA G160M 1533 none none none 3 2 N/A G HD-131156B 5 COS/FUV TIME-TA PSA G160M 1533 none none none 4 2 N/A G 17839( 3) - 16-Aug-2024 11:10:03 - [ 6] Visit: 11 Visit Requirements: GYRO MODE 1G; SCHED 100%; ORIENT 315D TO 195 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD-165341A COS/NUV ACQ/IMA BOA MIRRORB 1 8 S (8 S) GS ACQ SCENARIO BASE1O3 GE Comments: Castelli-Kurucz Models K0V, renormalized to vegamag = 4.22 in filter Johnson/V (from BSC and WDS) ------------------------------------------------------------------------------------------------------------------------------------ 2 HD-165341A COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=2800, FP-POS=ALL, 1 164 S (656 G LIFETIME-POS=LP4 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 HD-165341A COS/FUV TIME-TA PSA G160M 1533 BUFFER-TIME=4300, FP-POS=ALL, 1 163 S (652 G LIFETIME-POS=LP4 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 HD-165341B COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=9200, FP-POS=ALL, 1 202 S (808 G LIFETIME-POS=LP4 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 HD-165341B COS/FUV TIME-TA PSA G160M 1533 BUFFER-TIME=12700, FP-POS=ALL, 1 202 S (808 G LIFETIME-POS=LP4 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HD-165341A 1 COS/NUV ACQ/IMA BOA MIRRORB none none none none 1 N/A GE HD-165341A 2 COS/FUV TIME-TA PSA G130M 1222 none none none 1 1 N/A G HD-165341A 2 COS/FUV TIME-TA PSA G130M 1222 none none none 2 1 N/A G HD-165341A 2 COS/FUV TIME-TA PSA G130M 1222 none none none 3 1 N/A G HD-165341A 2 COS/FUV TIME-TA PSA G130M 1222 none none none 4 1 N/A G HD-165341A 3 COS/FUV TIME-TA PSA G160M 1533 none none none 1 1 N/A G HD-165341A 3 COS/FUV TIME-TA PSA G160M 1533 none none none 2 1 N/A G HD-165341A 3 COS/FUV TIME-TA PSA G160M 1533 none none none 3 1 N/A G HD-165341A 3 COS/FUV TIME-TA PSA G160M 1533 none none none 4 1 N/A G 17839( 3) - 16-Aug-2024 11:10:03 - [ 7] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HD-165341B 4 COS/FUV TIME-TA PSA G130M 1222 none none none 1 2 N/A G HD-165341B 4 COS/FUV TIME-TA PSA G130M 1222 none none none 2 2 N/A G HD-165341B 4 COS/FUV TIME-TA PSA G130M 1222 none none none 3 2 N/A G HD-165341B 4 COS/FUV TIME-TA PSA G130M 1222 none none none 4 2 N/A G HD-165341B 5 COS/FUV TIME-TA PSA G160M 1533 none none none 1 2 N/A G HD-165341B 5 COS/FUV TIME-TA PSA G160M 1533 none none none 2 2 N/A G HD-165341B 5 COS/FUV TIME-TA PSA G160M 1533 none none none 3 2 N/A G HD-165341B 5 COS/FUV TIME-TA PSA G160M 1533 none none none 4 2 N/A G 17839( 3) - 16-Aug-2024 11:10:03 - [ 8] Summary Form for Proposal 17839 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures BOA, PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=12700, BUFFER-TIME=13400, BUFFER-TIME=2400, BUFFER-TIME=2800, BUFFER-TIME=4000, BUFFER-TIME=4300, BUFFER-TIME=9200, BUFFER-TIME=9300, FP-POS=ALL, LIFETIME-POS=LP4 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1O3, GYRO MODE 1G, ORIENT 130D TO 10 D, ORIENT 315D TO 195 D, SCHED 100% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, G160M, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD-131156A, HD-131156B, HD-165341A, HD-165341B ------------------------------------------------------------------------------------------------------------------------------------