7304( 8) - 02/23/99 17:15 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7304 Version: 8 Check-in Date: 18-Mar-1998 16:37:41 1.Proposal Title: High Resolution Imaging and Spectroscopy of Cool Hypergiants Near the Top of the HR Diagram ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Roberta Humphreys University of Minnesota CoI: Kris Davidson University of Minnesota N CoI: Terry J. Jones University of Minnesota N CoI: Robert D. Gehrz University of Minnesota N CoI: Joachim Krautter Landessternwarte, Heidelberg N CoI: Thomas Szeifert Landessternwarte, Heidelberg N ------------------------------------------------------------------------------------ 5. Abstract A few highly unstable, very massive stars lie on or near the empirical upper luminosity boundary in the HR diagram. These include the Luminous Blue Variables, the cool hypergiants and other even rarer objects, all related by the violent mass loss phenomena responsible for the upper boundary. Our targets are IRC +10420 and VY CMa, very luminous cool stars with visible nebulosity. We propose to obtain STIS long-slit spectroscopy of the nebulosity and condensations revealed by our recent PC images of IRC+10420, plus images with the PC of the reflection nebula associated with the M supergiant VY CMa. These observations are needed for studies of the morphology and composition of the ejecta from these cool hypergiants. ------------------------------------------------------------------------------------ 7304( 8) - 02/23/99 17:15 - [ 2] Observations Description ------------------------ (*** See addenda regarding REVISIONS, #3 appended below ***) 1. WFPC2(PC) imaging of VY CMa. This bright variable red supergiant has V ~ 8-10 mag. Because the star is so bright and we are interested in the reflection nebula, the medium- band Stromgren filters v(F410M), b(F467M) and y(F547M) will be used for continuum imaging. As in our Cy6 IRC+10420 project, we've planned a series of exposures for each filter, with the shortest chosen to minimize bleeding from the central star and the longest to image the faint outer parts of the nebulosity. The exposure times are (0.5s, 2s, 5s, 12s) with F547M, (1s, 3s, 10s, 30s, 30s) with F467M and (5s, 15s, 60s, 60s) with F410M; with standard allowances for acquisition and overhead time this fills one orbit. 2. STIS spectrosopy of IRC+10420. Three types of material should be sampled: the star itself, some radial streamers reminiscent of the equatorial debris of Eta Car, and diffuse regions such as the ``beard'' south of the star (figs.1 & 2). Unfortunately no single slit position is good for all three, so we propose to use two slit positions about 0.5" apart (fig 1). Two slit positions do not require twice as much total time as one, because much of our time-budget involves allowances for grating-tilt changes which do not depend on the number of slit positions. (With STIS, a small position offset is much quicker than a change of grating or tilt.) A range of about 20degrees in the slit orientation is acceptable. For the star and nearby ejecta we use grating G750M at standard tilts with central wavelengths 8310 Angstrom (Ca II lines), 7800 Angstrom (O I), 7280 Angstrom (Ca II), and 6768 Angstrom (HAlpha + S II), and G430M centered at 4961 Angstrom (for HBeta) and 4706 Angstrom (abs lines). A sample count- rate estimate --- With considerable interstellar reddening, IRC+10420 has V ~ 11, B ~ 13.7 magn with the 10" apertures typically used for ground- based photometry. Our PC images show that about half the light is coming from the reflection nebula at BV wavelengths, so the central star's magnitudes are V ~ 12 and B ~ 14.5. Our PC images give surface brightnesses at `b' and `y' wavelengths, which can be extrapolated to longer wavelengths with the aid of ground- based total fluxes and reasonable assumptions. Thus I_lambda(6000 Angstrom) ~ 3 * 10^-14 erg cm^-2 s^-1 AA^-1 arcsec^-2 at r ~ 0.5". , The sensitivity with grating G750M is Sens_lambda^d(6000 Angstrom) ~ 4.6 * 10^12 appropriate units, , so the count rate in a 6-pixel sample with N_spix = 3 and N_Lambdapix = 2 is (3 * 10^-14) * (4.6 * 10^12) * 3 * 2 ~ 0.8 cts/s near 6000 Angstrom. Similar calculations for Lambda = 4600 and 8000 Angstrom give rates about 20 times lower and 4 times higher, respectively. The star is expected to give about 200 cts/s in a 6-pixel sample at 6000 Angstrom and is even redder than the diffuse stuff. Material 1.5" to 4" from the star is fainter than that at 0.4" by factors of 10 to 200, so there we use only low-resolution grating G750L. (On the other hand, we can use wider spatial samples for those outlying regions.) Orbit-time budget: Assumptions --- Unless otherwise stated, we give positions 1 and 2 (slit on star and 0.5" away, fig. 1) the same exposure time t_exp. Overhead allowance is 5 min for each grating tilt plus 1 min readout time for each observation (CR-split assumed, though it may be unnecessary with short exp times). We omit the small allowance for each position change; if necessary, readout times can be reduced by reading only a subarray. Each orbit has 52 minutes of ``visibility'', so the first orbit has 25 min of useful time after deducting 27 min for guide star acq., target acq., peakup, and STIS preparation. Each orbit after that has 46 min of useful time following guide star re- acq. First orbit G750M/8310Angstrom, exposure time t_exp = 4 min at each position takes 15 min; then G750M/7800Angstrom, one position only, with t_exp = 4 min takes ~ 10 min. Second orbit: Second position with G750M/7800Angstrom, t_exp = 4 min, takes ~ 5 min (no grating- tilt change). G750M/7280Angstrom and G750M/6768Angstrom with t_exp ~ 6.5 min take 40 min (2 tilts, 4 exposures). Third orbit: Position 1 only. G430M/4706Angstrom with t_exp = 24 min takes 30 minutes, then G430M/4961Angstrom with t_exp = 10 min takes 16 minutes. Fourth orbit: Position 2 only, G430M/4961Angstrom with a longer exposure to detect fainter diffuse HBeta emission. There is enough time for t_exp ~ 44 minutes. . 3. REVISIONS, March 1998: The STIS program is essentially unchanged except that the grating-tilt sequence has been rearranged to allow "fringe flat" exposures before or after each orbit's visibility time. Also, GAIN = 4 is specified for some of the short exposures, to get good unsaturated pixels in the brightest regions. In the WFPC2 plan for VY CMa, filter F467M has been replaced by F1042M in this version, because recently published FOC images indicate that the longer wavelengths now deserve higher priority than F467M. Real Time Justification ----------------------- In order to sample the diffuse material approximately as indicated in fig 1, the STIS slit should be oriented near PA ~ 50degrees or 230degrees, within a range of 15degrees or 20degrees Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 7304( 8) - 02/23/99 17:15 - [ 3] Data Distribution Paper Products: Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7304( 8) - 02/23/99 17:15 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 IRC+10420- STAR, F0-F2, LUMINOUS RA=19H 26M 48.02S +/- 0.1S, J2000 V = 12.0+/-0.5 OFFSET BLUE VARIABLE, DEC=11D 21' 18.0" +/- 1.5", B-V = 2.5+/-0.5 IRREGULAR VARIABLE, PLATE-ID=02V0 E(B-V) = 2.5+/-0.7 EJECTA Comments: The star itself, plus some ejecta within about 3 arcsec 2 IRC+10420- STAR, EJECTA R=0.61", PA=102D, FROM 1 J2000 F(5500)=1.8+/-0.2e-14 50S E(B-V) = 2.5+/-0.7 V = 13.5+/-0.5 Comments: Ejecta about 0.5 to 3 arcsec from the star 3 VY-CMA STAR, M III-I, RA=7H 22M 58.15S +/- 0.2S, DEC=- J2000 V = 10.0+/-1.0 IRREGULAR VARIABLE, 25D 46' 2.57" +/- 0.2" B-V = 2.0+/-0.5 EJECTA E(B-V) = 0.5+/-0.2 Comments: Red Supergiant - variable between 8 and 10th magnitude in V 7304( 8) - 02/23/99 17:15 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 87D TO 107D On Hold Comments: Additional Comments: Equally good orientation is 267D to 287D. The middle of the ORIENT range is much preferred: 92-102 and 272-282 are best. We want the STIS slit fairly close to PA 52 = 232. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 IRC+10420-O STIS/C ACQ F25ND3 MIRROR 1 2.0 S ONBOARD ACQ FOR 20 FFSET CD ------------------------------------------------------------------------------------------------------------------------------------ 20 IRC+10420-O STIS/C ACQ/PEA 52X0.1 G750M 8311 1 2.0 S ONBOARD ACQ FOR 130-420 FFSET CD K ------------------------------------------------------------------------------------------------------------------------------------ 130 IRC+10420-O STIS/C ACCUM 52X0.1 G750M 6768 CR-SPLIT=NO,GAIN=4 1 8 S MAX DUR FFSET CD Comments: Special short exposure for H-alpha in star ------------------------------------------------------------------------------------------------------------------------------------ 140 IRC+10420-O STIS/C ACCUM 52X0.1 G750M 6768 CR-SPLIT=2,GAIN=4 1 30 S MAX DUR FFSET CD Comments: Short exposure, H-alpha in star ------------------------------------------------------------------------------------------------------------------------------------ 150 IRC+10420-O STIS/C ACCUM 52X0.1 G750M 6768 CR-SPLIT=2 1 6.0 M FFSET CD Comments: H-alpha in star will saturate ------------------------------------------------------------------------------------------------------------------------------------ 160 IRC+10420-O STIS/C ACCUM 52X0.1 G750M 8311 CR-SPLIT=3 1 4.5 M FFSET CD ------------------------------------------------------------------------------------------------------------------------------------ 170 IRC+10420-5 STIS/C ACCUM 52X0.1 G750M 8311 1 4.5 M 0S CD ------------------------------------------------------------------------------------------------------------------------------------ 180 CCDFLAT STIS/C ACCUM 52X0.1 G750M 8311 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 200 CCDFLAT STIS/C ACCUM 52X0.1 G750M 7795 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 210 IRC+10420-O STIS/C ACCUM 52X0.1 G750M 7795 CR-SPLIT=3 1 4 M FFSET CD ------------------------------------------------------------------------------------------------------------------------------------ 220 IRC+10420-5 STIS/C ACCUM 52X0.1 G750M 7795 1 4 M 0S CD ------------------------------------------------------------------------------------------------------------------------------------ 230 IRC+10420-5 STIS/C ACCUM 52X0.1 G750M 6768 CR-SPLIT=2 1 6 M 0S CD ------------------------------------------------------------------------------------------------------------------------------------ 240 IRC+10420-O STIS/C ACCUM 52X0.1 G750M 7283 CR-SPLIT=3 1 6 M FFSET CD ------------------------------------------------------------------------------------------------------------------------------------ 7304( 8) - 02/23/99 17:15 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 250 IRC+10420-5 STIS/C ACCUM 52X0.1 G750M 7283 CR-SPLIT=2 1 6 M 0S CD ------------------------------------------------------------------------------------------------------------------------------------ 260 CCDFLAT STIS/C ACCUM 52X0.1 G750M 7283 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 310 IRC+10420-O STIS/C ACCUM 52X0.1 G430M 4706 CR-SPLIT=NO 1 1 M MAX DUR FFSET CD Comments: Special short exposure for star emiss line center ------------------------------------------------------------------------------------------------------------------------------------ 320 IRC+10420-O STIS/C ACCUM 52X0.1 G430M 4706 CR-SPLIT=4 1 24 M FFSET CD ------------------------------------------------------------------------------------------------------------------------------------ 330 IRC+10420-O STIS/C ACCUM 52X0.1 G430M 4961 CR-SPLIT=3 1 10 M FFSET CD ------------------------------------------------------------------------------------------------------------------------------------ 410 IRC+10420-5 STIS/C ACCUM 52X0.1 G430M 4961 CR-SPLIT=2 1 3 M 0S CD Comments: Short exposure ------------------------------------------------------------------------------------------------------------------------------------ 420 IRC+10420-5 STIS/C ACCUM 52X0.1 G430M 4961 CR-SPLIT=4 1 36 M 0S CD ------------------------------------------------------------------------------------------------------------------------------------ 7304( 8) - 02/23/99 17:15 - [ 7] Visit: 02 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 610 VY-CMA WFPC2 IMAGE PC1 F547M ATD-GAIN=15 1 0.11 S MAX DUR ------------------------------------------------------------------------------------------------------------------------------------ 612 VY-CMA WFPC2 IMAGE PC1 F547M ATD-GAIN=15 1 0.5 S MAX DUR ------------------------------------------------------------------------------------------------------------------------------------ 614 VY-CMA WFPC2 IMAGE PC1 F547M ATD-GAIN=15 1 2.0 S ------------------------------------------------------------------------------------------------------------------------------------ 616 VY-CMA WFPC2 IMAGE PC1 F547M ATD-GAIN=15 1 5.0 S ------------------------------------------------------------------------------------------------------------------------------------ 618 VY-CMA WFPC2 IMAGE PC1 F547M CLOCKS=YES 1 16.0 S Comments: Star image will be heavily saturated ------------------------------------------------------------------------------------------------------------------------------------ 620 VY-CMA WFPC2 IMAGE PC1 F410M ATD-GAIN=15 1 5.0 S MAX DUR ------------------------------------------------------------------------------------------------------------------------------------ 622 VY-CMA WFPC2 IMAGE PC1 F410M ATD-GAIN=15 1 16.0 S ------------------------------------------------------------------------------------------------------------------------------------ 624 VY-CMA WFPC2 IMAGE PC1 F410M CLOCKS=YES,CR-SPLIT=0.50 1 120 S Comments: Star image will be heavily saturated ------------------------------------------------------------------------------------------------------------------------------------ 630 VY-CMA WFPC2 IMAGE PC1 F656N ATD-GAIN=15 1 0.4 S MAX DUR ------------------------------------------------------------------------------------------------------------------------------------ 632 VY-CMA WFPC2 IMAGE PC1 F656N ATD-GAIN=15 1 2.0 S ------------------------------------------------------------------------------------------------------------------------------------ 634 VY-CMA WFPC2 IMAGE PC1 F656N ATD-GAIN=15 1 15.0 S ------------------------------------------------------------------------------------------------------------------------------------ 636 VY-CMA WFPC2 IMAGE PC1 F656N CLOCKS=YES,CR-SPLIT=0.5 1 60.0 S Comments: Star image will be heavily saturated ------------------------------------------------------------------------------------------------------------------------------------ 640 VY-CMA WFPC2 IMAGE PC1 F1042M ATD-GAIN=15 1 0.11 S MAX DUR ------------------------------------------------------------------------------------------------------------------------------------ 642 VY-CMA WFPC2 IMAGE PC1 F1042M ATD-GAIN=15 1 0.5 S ------------------------------------------------------------------------------------------------------------------------------------ 644 VY-CMA WFPC2 IMAGE PC1 F1042M ATD-GAIN=15 1 3.0 S ------------------------------------------------------------------------------------------------------------------------------------ 646 VY-CMA WFPC2 IMAGE PC1 F1042M CLOCKS=YES,CR-SPLIT=0.5 1 15.0 S Comments: Star image will be heavily saturated ------------------------------------------------------------------------------------------------------------------------------------ 7304( 8) - 02/23/99 17:15 - [ 8] Summary Form for Proposal 7304 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F25ND3 52X0.1 PC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO GAIN=4 CR-SPLIT=2 CR-SPLIT=3 CR-SPLIT=4 ATD-GAIN=15 CLOCKS=YES CR-SPLIT=0.50 CR-SPLIT=0.5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 87D TO 107D ONBOARD ACQ FOR 20 ONBOARD ACQ FOR 130-420 MAX DUR ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G750M G430M F547M F410M F656N F1042M ------------------------------------------------------------------------------------------------------------------------------------ Target Names IRC+10420-OFFSET IRC+10420-50S CCDFLAT VY-CMA ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 8311 6768 7795 7283 4706 4961 ------------------------------------------------------------------------------------------------------------------------------------