13800( 4) - 07-Jan-2015 17:39:43 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13800 Version: 4 Check-in Time: 07-Jan-2015 17:39:43 STScI Edit Number: 1 Title Heavy-metal, extreme chemistry and puzzling pulsation: ultraviolet clues to the formation of hot subdwarfs ------------------------------------------------------------------------------------ Type Cycle GO 22 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. C. Simon Jeffery Armagh Observatory Y ------------------------------------------------------------------------------------ Abstract Subdwarf B stars are low-mass core-helium burning stars with a very thin hydrogen envelope; in most cases, surface helium and light elements are depleted, heavy elements are enhanced by a factor ten. It is argued that normal He-poor sdB stars evolve from giants which have been stripped almost to the core to reveal helium-enriched material. As the star ignites helium and contracts to the extreme horizontal branch, radiative processes re-stratify the internal chemistry of the atmosphere and the helium sinks. When does this happen, how long does it take, and what does it look like? A small number of sdB stars have intermediate helium abundances (He-sdB) and a few have extraordinary surface compositions. The pulsating "zirconium" star LS IV-14 116 shows a four dex overabundance of zirconium, yttrium and strontium. Two other He-sdBs show a four dex overabundace of lead. Such stars are almost completely unexplored in the space ultraviolet. We will observe the ultraviolet spectrum of LS IV-14 116 and two other chemically peculiar hot subdwarfs in order to determine: (a) the impact of extraordinary composition on their overall flux distribution and hence on measurements of their effective temperatures, (b) the degree of stratification in the atmosphere (how thick is the enhanced layer?), and (c) the abundances of species not observable in the visible. (d) the ultraviolet lightcurve due to the principle pulsation modes of LS IV-14 116. The observations will allow us to explore the processes that lead to heavily stratified atmospheres and to the transformation of red giants with helium-enriched surface into horizontal-branch stars with helium-poor surfaces. ------------------------------------------------------------------------------------ Observations Description ------------------------ 1. Description of Observations. We require wide spectral coverage observations of ALS-11634 (LS IV-14 116), PG 0909+276 and [CW83] 0512-08, in the NUV and FUV at a spectral resolution sufficient to resolve narrow lines in crowded spectral regions. A S/N ratio better than 30 at a spectral resolution 30000 is normally required to establish chemical abundances with confidence. The required data are provided by the medium-resolution echelle E230M and E140M grisms centered at 1978 A and 1425 A to cover the wavelength ranges 1700-2370 A and 1160-1730 A respectively. 13800( 4) - 07-Jan-2015 17:39:43 - [ 2] We also require time-resolved FUV spectroscopy of ALS-11634 (LS IV-14 116) in order to measure the flux variation due to the principal pulsation mode (P = 1957 s). The pulsation amplitude is 0.27% in white light (22), and is expected to be more than this in the FUV by a factor of a few, so we require < 0.1% photometric precision with a time resolution better than 10/P, i.e. texp ~ 180s. Photometric precision can be achieved by a combination of binning over wavelength and/or phase. FUV times-series spectroscopy will also be obtained with the medium-resolution echelle and E140M grism centered at 1425 A, using repeated 180 s exposures. The observations will be obtained on 3 visits comprising a total of 7 orbits as allocated. Visit 1: 1 Orbit: TYC-5331-1560-1 = CW 0512-08 to acquire both NUV and FUV spectra in the same orbit. Visit 2: 2 Orbits: TYC-1954-398-1 = PG 0909+276 to acquire both NUV and FUV spectra, one in each orbit. Visit 3. 4 Orbits: ALS-11364 = LS IV -14 116 to acquire the mean NUV spectrum (one orbit) and time-resolved exposures of the FUV spectrum (three orbits). 2, Justification of Real-time Observations and Special Scheduling We have no real-time or special scheduling requirements. We will endeavour to obtain simultaneous, or near-simultaneous ground-based observations for Visit 3 if the likely schedule is known sufficiently well in advance. 3. Justification of Special Calibration Requirements No special calibrations are required, except that for the repeated FUV spectra of LS IV -14 116 we ask that WAVECAL exposures are carried out during the Earth Occultation periods in or der to maximise on-target exposure times. 4. Additional Comments ------------------------------------------------------------------------------------ 13800( 4) - 07-Jan-2015 17:39:43 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 ALS-11634 STAR, PULSATING RA=20H57M38.8400S, J2000 V = 13.029 VARIABLE, SDO DEC=-14D25'41.60" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 2 TYC-1954-398 STAR, SDO RA=09H12M51.6620S, J2000 V = 12.1 -1 DEC=+27D20'31.43" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 3 TYC-5331-156 STAR, SDO RA=05H14M43.9700S, J2000 V = 11.34 0-1 DEC=-08D48'6.00" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 13800( 4) - 07-Jan-2015 17:39:43 - [ 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 TYC-5331-15 STIS/CCD ACQ F28X50LP MIRROR 1 0.1 S (0.1 60-1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 TYC-5331-15 STIS/CCD ACQ/PEA 0.2X0.06 MIRROR 1 0.1 S (0.1 60-1 K S) ------------------------------------------------------------------------------------------------------------------------------------ 3 TYC-5331-15 STIS/FUV ACCUM 0.2X0.06 E140M 1425 1 1000 S 60-1 -MAMA see below (1006 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 TYC-5331-15 STIS/NUV ACCUM 0.2X0.06 E230M 2124 1 690 S 60-1 -MAMA see below (696 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 | ------------------------------------------------------------------------------------------------------------------------------------ TYC-5331-1560-1 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A TYC-5331-1560-1 2 STIS/CCD ACQ/PEA 0.2X0.06 MIRROR none none none none 1 N/A K TYC-5331-1560-1 3 STIS/FUV ACCUM 0.2X0.06 E140M 1425 none none none none 1 1006.0 S -MAMA TYC-5331-1560-1 4 STIS/NUV ACCUM 0.2X0.06 E230M 2124 none none none none 1 696.0 S -MAMA 13800( 4) - 07-Jan-2015 17:39:43 - [ 5] 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 TYC-1954-39 STIS/CCD ACQ F28X50LP MIRROR 1 1 S (1 S) 8-1 ------------------------------------------------------------------------------------------------------------------------------------ 2 TYC-1954-39 STIS/CCD ACQ/PEA 0.2X0.06 MIRROR 1 1.8 S (1.8 8-1 K S) ------------------------------------------------------------------------------------------------------------------------------------ 3 TYC-1954-39 STIS/NUV ACCUM 0.2X0.06 E230M 2124 1 2100 S 8-1 -MAMA see below (2019 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 TYC-1954-39 STIS/FUV ACCUM 0.2X0.06 E140M 1425 1 3000 S 8-1 -MAMA see below (2989 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 | ------------------------------------------------------------------------------------------------------------------------------------ TYC-1954-398-1 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A TYC-1954-398-1 2 STIS/CCD ACQ/PEA 0.2X0.06 MIRROR none none none none 1 N/A K TYC-1954-398-1 3 STIS/NUV ACCUM 0.2X0.06 E230M 2124 none none none none 1 2019.0 S -MAMA TYC-1954-398-1 4 STIS/FUV ACCUM 0.2X0.06 E140M 1425 none none none none 2 2989.0 S -MAMA 13800( 4) - 07-Jan-2015 17:39:43 - [ 6] Visit: 03 Visit Requirements: BETWEEN 23-AUG-2015:00:00:00 AND 28-AUG-2015:00:00:00; VISIBILITY INTERVAL 53 M 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 ALS-11634 STIS/CCD ACQ F28X50LP MIRROR 1 0.1 S (0.1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ALS-11634 STIS/CCD ACQ/PEA 0.2X0.06 MIRROR 1 0.1 S (0.1 K S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ALS-11634 STIS/NUV ACCUM 0.2X0.06 E230M 2124 1 2300 S -MAMA see below (1996 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ALS-11634 STIS/FUV ACCUM 0.2X0.2 E140M 1425 39 180 S -MAMA see below (7137 S) Comments: 0.2x0.2 aperture chosen for photometric precision. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ALS-11634 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A ALS-11634 2 STIS/CCD ACQ/PEA 0.2X0.06 MIRROR none none none none 1 N/A K ALS-11634 3 STIS/NUV ACCUM 0.2X0.06 E230M 2124 none none none none 1 1996.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 1 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 2 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 3 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 4 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 5 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 6 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 7 none 2 177.0 S -MAMA 13800( 4) - 07-Jan-2015 17:39:43 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 8 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 9 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 10 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 11 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 12 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 13 none 2 177.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 14 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 15 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 16 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 17 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 18 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 19 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 20 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 21 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 22 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 23 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 24 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 25 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 26 none 3 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 27 none 4 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 28 none 4 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 29 none 4 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 30 none 4 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 31 none 4 186.0 S -MAMA 13800( 4) - 07-Jan-2015 17:39:43 - [ 8] 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 | ------------------------------------------------------------------------------------------------------------------------------------ ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 32 none 4 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 33 none 4 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 34 none 4 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 35 none 4 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 36 none 4 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 37 none 4 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 38 none 4 186.0 S -MAMA ALS-11634 4 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none 39 none 4 186.0 S -MAMA 13800( 4) - 07-Jan-2015 17:39:43 - [ 9] Summary Form for Proposal 13800 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 0.2X0.06, 0.2X0.2, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ, ACQ/PEAK ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 23-AUG-2015:00:00:00 AND 28-AUG-2015:00:00:00, VISIBILITY INTERVAL 53 M ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements E140M, E230M, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names ALS-11634, TYC-1954-398-1, TYC-5331-1560-1 ------------------------------------------------------------------------------------------------------------------------------------