13861( 4) - 07-Nov-2014 12:46:19 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13861 Version: 4 Check-in Time: 07-Nov-2014 12:46:19 STScI Edit Number: 0 Title HST/COS FUV Spectrophotometry of the Key Binary Solar Twins 16 Cyg A&B: Astrophysical Laboratories for the Future Sun and Older Solar Analogs ------------------------------------------------------------------------------------ Type Cycle GO 22 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Edward F. Guinan Villanova University Y CoI: Dr. Laurence Dewarf Villanova University N CoI: Dr. Travis S. Metcalfe Space Science Institute N CoI: Dr. Philip G. Judge University Corporation For Atmospheric N Research CoI: Mr. Scott G. Engle Villanova University N ------------------------------------------------------------------------------------ Abstract The fortuitous location of the wide G1.5V/G2.5V binary 16 Cyg A&B as the brightest stars in the Kepler Field is a "game changer, " permitting the determination of the stars' fundamental properties from asteroseismolgy analyses. Recent studies returned precise determinations of the stars' basic properties including masses and age (6.8+/-0.4 Gyr), along with the rotation periods. Thus, 16 Cyg A&B are now the oldest solar-mass analogs with reliable ages and physical properties. Only the Sun has better determined physical properties. 16 Cyg A&B now serve as old-age anchors for Rotation-Age-Activity-Irradiance relations (and Gyrochronology studies) for solar-type stars. Extensive Ca II HK spectrophotometry reveals low levels of chromospheric emission are below the lowest values for our Sun. These stars serve as critical test beds for studying solar/stellar dynamos for stars less active than the Sun. These advances have catapulted 16 Cyg A&B into a prominent place in solar/stellar astrophysics for studying the evolution, internal structure, magnetic dynamos, angular momentum loss, and FUV irradiances of old solar-mass stars. Although 16 Cyg has been observed from X-ray - IR, there are no observations in the FUV region where most of the crucial diagnostic chromospheric & transition region emissions occur. We request COS FUV medium resolution (G130M, G160M) spectra (six orbits/star). This permits the important FUV (1150-1750A) line emission strengths, profiles and Doppler shifts to be analyzed and compared with the Sun and other solar-analogs. This program is complemented by Ca II HK, high precision uvby observations, and by proposed Chandra X-ray coronal observations. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose HST/COS FUV 1150-1750A observations of 16 Cyg A&B (six HST orbits per star) to secure good signal/noise (S/N) medium resolution G130M and G160M spectrophotometry. We plan to use the Primary Science Aperture (PSA). Accounting for acquisitions, overheads and utilizing the "re-acquire" between orbits, this request will result in ~5.1 ksec (over 3 orbits) per G130M and G160M elements. We used our previous HST/COS FUV spectra of the solar twin 18 Sco (G2 V; V = 5.50 mag; d = 13.90 pc; age = 3.9 +/- 0.5 Gyr) and archival COS FUV spectra of alpha Cen A (G2 V; V = -0.01; d = 1.34 pc; age = 4.9 +/- 0.7 Gyr) to estimate exposure times and signal-to-noise (S/N) values for the 13861( 4) - 07-Nov-2014 12:46:19 - [ 2] important FUV emissions. We scaled these fluxes (via the inverse square law) to the distance of 16 Cyg A&B (d = 21.10 pc). Also, because 16 Cyg A&B are older, and from lower Ca II H&K emissions, we assumed that their FUV line fluxes could be ~60-75% lower. Our calculations show that 3 consecutive HST orbits with the G130M and G160M elements are required for each star. These exposures will result in S/N (~5-10) for the moderate-to-strong emission lines. The resulting FUV spectra will be suitable for securing reliable integrated emission line fluxes needed to carry out spectral diagnostics from emission line ratios, performing a Volume Emission Measure (VEM) analyses, as well as modeling the line profiles. Importantly, the simulations indicate that the resulting COS/FUV spectra will permit some of the weaker, but important, diagnostic line emissions to be measured and used to determine the physical properties of the stars' chromospheres and transition regions. These spectra will be compared with comparable FUV spectra available for the Sun from solar FUV/UV space missions such as SOLSTICE (SORCE). Also we plan direct differential comparisons with the HST/STIS or COS FUV spectra of alpha Cen A and 18 Sco. ------------------------------------------------------------------------------------ 13861( 4) - 07-Nov-2014 12:46:19 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 -16-CYG-A STAR, G V-IV RA=19H41M48.9534S +/- 0.3", J2000 V = V = 5.95 +/- 0.01 G1.5V DEC=+50D31'30.22" +/- 0.3" -27.61 Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -0.015501079945702574 -0.15900999999999998 0.04744 ------------------------------------------------------------------------------------------------------------------------------------ 2 -16-CYG-B STAR, G V-IV RA=19H41M51.9720S +/- 0.3", J2000 V = V = 6.2 +/- 0.01 G3V DEC=+50D31'3.08" +/- 0.3" -28.02 Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -0.014165988297315508 -0.16378 0.04714 ------------------------------------------------------------------------------------------------------------------------------------ 13861( 4) - 07-Nov-2014 12:46:19 - [ 4] Visit: 01 Visit Requirements: 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 -16-CYG-A COS/NUV ACQ/SEA PSA G285M 2676 SCAN-SIZE=3, STEP-SIZE=1.767, 1 0.6 S (0.6 RCH CENTER=FLUX-WT-FLR S) ------------------------------------------------------------------------------------------------------------------------------------ 2 -16-CYG-A COS/NUV ACQ/PEA PSA G285M 2676 STRIPE=MEDIUM 1 0.6 S (0.6 KXD S) ------------------------------------------------------------------------------------------------------------------------------------ 3 -16-CYG-A COS/NUV ACQ/PEA PSA G285M 2676 NUM-POS=5, STEP-SIZE=0.9, 1 0.6 S (0.6 KD CENTER=FLUX-WT-FLR S) ------------------------------------------------------------------------------------------------------------------------------------ 4 -16-CYG-A COS/FUV TIME-TA PSA G130M 1291 FP-POS=ALL, BUFFER-TIME=700 1 1700 S G see below (11677 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 -16-CYG-A COS/FUV TIME-TA PSA G160M 1577 FP-POS=ALL, BUFFER-TIME=500 1 1200.0 S G see below (5882 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 | ------------------------------------------------------------------------------------------------------------------------------------ -16-CYG-A 1 COS/NUV ACQ/SEA PSA G285M 2676 none none none none 1 N/A RCH -16-CYG-A 2 COS/NUV ACQ/PEA PSA G285M 2676 none none none none 1 N/A KXD -16-CYG-A 3 COS/NUV ACQ/PEA PSA G285M 2676 none none none none 1 N/A KD -16-CYG-A 4 COS/FUV TIME-TA PSA G130M 1291 none none none 1 1 2308.0 S G -16-CYG-A 4 COS/FUV TIME-TA PSA G130M 1291 none none none 2 2 3123.0 S G -16-CYG-A 4 COS/FUV TIME-TA PSA G130M 1291 none none none 3 3 3123.0 S G -16-CYG-A 4 COS/FUV TIME-TA PSA G130M 1291 none none none 4 4 3123.0 S G -16-CYG-A 5 COS/FUV TIME-TA PSA G160M 1577 none none none 1 5 1470.0 S G -16-CYG-A 5 COS/FUV TIME-TA PSA G160M 1577 none none none 2 5 1470.0 S G 13861( 4) - 07-Nov-2014 12:46:19 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ -16-CYG-A 5 COS/FUV TIME-TA PSA G160M 1577 none none none 3 6 1471.0 S G -16-CYG-A 5 COS/FUV TIME-TA PSA G160M 1577 none none none 4 6 1471.0 S G 13861( 4) - 07-Nov-2014 12:46:19 - [ 6] Visit: 02 Visit Requirements: 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 -16-CYG-B COS/NUV ACQ/SEA PSA G285M 2676 SCAN-SIZE=3, STEP-SIZE=1.767, 1 0.8 S (0.8 RCH CENTER=FLUX-WT-FLR S) ------------------------------------------------------------------------------------------------------------------------------------ 2 -16-CYG-B COS/NUV ACQ/PEA PSA G285M 2676 STRIPE=MEDIUM 1 0.8 S (0.8 KXD S) ------------------------------------------------------------------------------------------------------------------------------------ 3 -16-CYG-B COS/NUV ACQ/PEA PSA G285M 2676 NUM-POS=5, STEP-SIZE=0.9, 1 0.8 S (0.8 KD CENTER=FLUX-WT-FLR S) ------------------------------------------------------------------------------------------------------------------------------------ 4 -16-CYG-B COS/FUV TIME-TA PSA G130M 1291 FP-POS=ALL, BUFFER-TIME=700 1 1700 S G see below (11674 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 -16-CYG-B COS/FUV TIME-TA PSA G160M 1577 FP-POS=ALL, BUFFER-TIME=500 1 1200 S G see below (5882 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 | ------------------------------------------------------------------------------------------------------------------------------------ -16-CYG-B 1 COS/NUV ACQ/SEA PSA G285M 2676 none none none none 1 N/A RCH -16-CYG-B 2 COS/NUV ACQ/PEA PSA G285M 2676 none none none none 1 N/A KXD -16-CYG-B 3 COS/NUV ACQ/PEA PSA G285M 2676 none none none none 1 N/A KD -16-CYG-B 4 COS/FUV TIME-TA PSA G130M 1291 none none none 1 1 2305.0 S G -16-CYG-B 4 COS/FUV TIME-TA PSA G130M 1291 none none none 2 2 3123.0 S G -16-CYG-B 4 COS/FUV TIME-TA PSA G130M 1291 none none none 3 3 3123.0 S G -16-CYG-B 4 COS/FUV TIME-TA PSA G130M 1291 none none none 4 4 3123.0 S G -16-CYG-B 5 COS/FUV TIME-TA PSA G160M 1577 none none none 1 5 1470.0 S G -16-CYG-B 5 COS/FUV TIME-TA PSA G160M 1577 none none none 2 5 1470.0 S G 13861( 4) - 07-Nov-2014 12:46:19 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ -16-CYG-B 5 COS/FUV TIME-TA PSA G160M 1577 none none none 3 6 1471.0 S G -16-CYG-B 5 COS/FUV TIME-TA PSA G160M 1577 none none none 4 6 1471.0 S G 13861( 4) - 07-Nov-2014 12:46:19 - [ 8] Summary Form for Proposal 13861 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAKD, ACQ/PEAKXD, ACQ/SEARCH, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=500, BUFFER-TIME=700, CENTER=FLUX-WT-FLR, FP-POS=ALL, NUM-POS=5, SCAN-SIZE=3, STEP-SIZE=0.9, STEP-SIZE=1.767, STRIPE=MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, G160M, G285M ------------------------------------------------------------------------------------------------------------------------------------ Target Names -16-CYG-A, -16-CYG-B ------------------------------------------------------------------------------------------------------------------------------------