Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 29 Report Date: 18-Jul-95:16:26 Version: ********** Check-in Date: ********** 1.Proposal Title: ULTRAVIOLET SPECTROPOLARIMETRY OF AA AND IN ITS CURRENT ACTIVITY ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO/DD Sub Category MASSIVE STARS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Joe Astronomer STSCI USA (301) 338-4700 ASTRONOMER ------------------------------------------------------------------------------------ 7. Abstract We propose to obtain high-resolution (R=1000) spectropolarimetry of the O-type variable AA And with the FOS. AA And undergoes quasi-periodic outbursts on a time- scale of about 45 years. The on-set of such an outburst has recently been detected. During the outburst, the stellar mass-loss rate increases by a factor of 2, leading to the ejection of discrete shells. It is intended to measure the linear polarization of strong ultraviolet resonance lines originating in the wind of AA And, such as Fe II (1) and Mg II (1) in the wavelength region 2300A-3100A. Such SCATTERING lines are the most sensitive probe to study asymmetries in the wind by spectropolarimetric techniques. The scientific goal is to search for evidence for asymmetry in the stellar wind of AA And within 10 stellar radii. The results will be interpreted in terms of the outburst mechanism of AA Andr, and of O stars in general. ------------------------------------------------------------------------------------ 8. Scientific Key Words: MASS LOSS, MASSIVE STARS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 1.11 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 29 PI: Dr. Joe Astronomer Proposal Title: ULTRAVIOLET SPECTROPOLARIMETRY OF AA AND IN ITS CURRENT ACTIVITY ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Dr. Joe Astronomer SPACE TELESCOPE SCIENCE USA INSTITUTE ------------------------------------------------------------------------------------ 3. Description of proposed observations. Target Acquisition Scenario: a four stage peak-up into the 0.5" aperture for AA AND: 4.3 aperture, a single line 3 point scan in the Y direction; 1.0 aperture, 2x6 scan to center in the X direction, step-size 0.7"; 0.5 aperture, 3x3 centered,stepsize 0.35"; 0.3 aperture, 3x3 centered, stepsize 0.2". For BD+55 (POL Standard) - three stage peakup into the 4.3": 4.3 aperture, a single line 3 point scan in the Y direction; 1.0 aperture, 2x6 scan to center in the X direction, step-size 0.7"; 0.5 aperture, 3x3 centered,stepsize 0.35" . Observations: Multiple visits, 800 seconds per POL series. An exposure time of 100 seconds per spectrum (100x8 waveplate positions) yields between 31,500 and 43,500 counts/diode (peak counts in spectra) depending on the brightness and stellar type of AA AND as it traverses it's phases. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The best way to detect asymmetries in the outflow of AA And is by measuring the polarization of scattering lines formed in the wind. In AA And, strong scattering occurs only in resonance transitions of ions like Fe+, Mg+, and others of comparable ionization potential. All these transitions are situated in the ultraviolet below 3000 A. Therefore such observations can not be obtained from the ground. Currently HST is the only space-borne instrument capable of doing ultraviolet spectropolarimetry. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. The exposure time has been calculated with the FOS instrument simulator. Although AA And will continue to brighten in the visual during the next months, the flux at 2500 A will remain nearly constant. The reason is the flux redistribution from the region around the Lyman edge to the Paschen continuum, which accounts for the increase in V. The flux at the maximum of the energy distribution at about 2500 A, however, is largely unaffected when AA And varies from early B to late B. We computed the expected energy distribution in the ultraviolet for a given V magnitude and the corresponding spectral type, with the total bolometric luminosity being constant. V magnitude/Spectral Type:7.75/B0.5Ia,7.50/B0.7Ia, 7.25/B1Ia,7.00/B2Ia,6.75/B3Ia,6.50/B5Ia,6.25/B8Ia,6.00/A0Ia. (E(B-V) = 0.63). Note that the star is well below the B/O limit for the FOS - both with respect to the integrated rate as well to the count rate per diode - due to the strong reddening. We find an integration time of 800 sec per polscan in order to reach an error of 0.7% based on photon statistics. 4 sequences are required for an accuracy of 0.3% so that the total integration time comes to 3200 sec per set of observations. The standard star will be measured for 800 sec per visit. Page 3 ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Since we intend to study the evolution of asymmetries during the outburst, it is essential to obtain the first set of observations as soon as permitted by scheduling constraints. We expect to gain insight into the ejection mechanism close to the stellar photosphere by the observations. Observations performed later in the outburst will sample wind regions further downstream in the flow due to the increasing mass-loss rate and optical depth in the wind. Therefore we request the first observations to be scheduled in JUNE/JULY 1991. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The data will be reduced and analysed at STScI as soon as they become available. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. The HST observations are supported by ground-based observations at the Kitt Peak National Observatory. ------------------------------------------------------------------------------------ 9. Description of previous HST work. A description of any previous HST data goes here. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Resources provided by your home institution goes here. ------------------------------------------------------------------------------------ 11. Address Information Name: JOE ASTRONOMER Category: PI Institution: STSCI Address: 3700 SAN MARTIN DRIVE City: BALTIMORE State: MD Zip Code: 21218 Country: USA Telephone: (301) 338-4700 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 29 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 AA- A,105,148 PLATE-ID=0TT5, 2000 1 V=8.3 +/- 0.5, TYPE=O4I, E(B- ANDROMEDAE RA=01H 22M 17.55S +/- 0.05S, V)=0.33 HD99111 DEC=+55D 47' 17.0" +/-0.4" ------------------------------------------------------------------------------------------------------------------------------------ 2 BD+55D101 A,111 PLATE-ID=7TY9, 2000 1 V=11.4 +/- 0.2 RA=05H 27M 19.71S +/- 0.03S, DEC=+55D 11' 45.1" +/-0.2" Comments: POLARIZATION STANDARD ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 29 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 AA- FOS/BL ACQ/ 4.3 G270H 1 0.1S 20 1 1 ONBOARD ACQ FOR 12 ANDROMEDAE PEAK SEQ 10-74 NO GAP SPATIAL SCAN CYCLE 1/10-74 Comments: COARSE PEAK-UP IN 4.3. ------------------------------------------------------------------------------------------------------------------------------------ 12 AA- FOS/BL ACQ/ 1.0 G270H 1 0.3S 20 1 1 ONBOARD ACQ FOR 14 ANDROMEDAE PEAK SPATIAL SCAN CYCLE 1 / 12-74 Comments: COARSE PEAK-UP IN 1.0 ------------------------------------------------------------------------------------------------------------------------------------ 14 AA- FOS/BL ACQ/ 0.5 G270H SEARCH-SIZE=3 1 0.5S 20 1 1 ONBOARD ACQ FOR 16 ANDROMEDAE PEAK SCAN-STEP=0.35 Comments: FINE PEAK-UP IN 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 16 AA- FOS/BL ACQ/ 0.3 G270H SEARCH-SIZE=3 1 0.5S 20 1 1 ONBOARD ACQ FOR 21 ANDROMEDAE PEAK SCAN-STEP=0.2 -51 Comments: PRECISE PEAK-UP IN 0.3. ------------------------------------------------------------------------------------------------------------------------------------ 21 AA- FOS/BL ACCUM 0.5 G270H POLSCAN=8B 1 800S 300 1 1 ANDROMEDAE ------------------------------------------------------------------------------------------------------------------------------------ 31 AA- FOS/BL ACCUM 0.5 G270H POLSCAN=8B 1 800S 300 1 1 ANDROMEDAE ------------------------------------------------------------------------------------------------------------------------------------ 41 AA- FOS/BL ACCUM 0.5 G270H POLSCAN=8B 1 800S 300 1 1 ANDROMEDAE ------------------------------------------------------------------------------------------------------------------------------------ 51 AA- FOS/BL ACCUM 0.5 G270H POLSCAN=8B 1 800S 300 1 1 ANDROMEDAE ------------------------------------------------------------------------------------------------------------------------------------ 70 BD+55D101 FOS/BL ACQ/ 4.3 G570H 1 1.0S 10 1 1 ONBOARD ACQ FOR 71 PEAK SPATIAL SCAN Comments: COARSE PEAKUP IN 4.3 ------------------------------------------------------------------------------------------------------------------------------------ 71 BD+55D101 FOS/BL ACQ/ 1.0 G570H 1 2.0S 10 1 1 ONBOARD ACQ FOR 72 PEAK SPATIAL SCAN Comments: COARSE PEAKUP IN 1.0 ------------------------------------------------------------------------------------------------------------------------------------ 72 BD+55D101 FOS/BL ACQ/ 0.5 G570H SEARCH-SIZE=3 1 2.0S 10 1 1 ONBOARD ACQ FOR 74 PEAK SCAN-STEP=0.35 Comments: FINE PEAK-UP IN 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 74 BD+55D101 FOS/BL ACCUM 4.3 G270H POLSCAN=8B 1 800S 100 1 1 Comments: HIGH POLARIZATION STANDARD TARGET. ------------------------------------------------------------------------------------------------------------------------------------ Scan Paramters Form Proposal ID: 29 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 1 Exposure Logsheet lines: 10 FGS Scan: N DWELL Dwell Only: dwell points/line: 3 Seconds per dwell: 0.10 Scan width (arc-secs): 0.0000 Scan length (arc-secs): 2.8660 Angle between sides (degrees) 0.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 0.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 1.4330 Width Offset (arc-sec): 0.0000 ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 2 Exposure Logsheet lines: 12 FGS Scan: N DWELL Dwell Only: dwell points/line: 6 Seconds per dwell: 0.30 Scan width (arc-secs): 0.7000 Scan length (arc-secs): 3.5000 Angle between sides (degrees) 90.00 Number of lines: 2 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 90.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 1.7500 Width Offset (arc-sec): 0.3500 ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 3 Exposure Logsheet lines: 70 FGS Scan: N DWELL Dwell Only: dwell points/line: 3 Seconds per dwell: 1.00 Scan width (arc-secs): 0.0000 Scan length (arc-secs): 2.8660 Angle between sides (degrees) 0.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 0.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 1.4330 Width Offset (arc-sec): 0.0000 ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 4 Exposure Logsheet lines: 71 FGS Scan: N DWELL Dwell Only: dwell points/line: 6 Seconds per dwell: 2.00 Scan width (arc-secs): 0.7000 Scan length (arc-secs): 3.5000 Angle between sides (degrees) 90.00 Number of lines: 2 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 90.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 1.7500 Width Offset (arc-sec): 0.3500 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 29 [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=3 SCAN-STEP=0.35 SCAN-STEP=0.2 POLSCAN=8B ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/DD ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 1.11 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category MASSIVE STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 12; SEQ 10-74 NO GAP; SPATIAL SCAN; CYCLE 1/10-74; ONBOARD ACQ FOR 14; CYCLE 1 / 12-74; ONBOARD ACQ FOR 16; ONBOARD ACQ FOR 21-51; ONBOARD ACQ FOR 71; SPATIAL SCAN ONBOARD ACQ FOR 72; ONBOARD ACQ FOR 74; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G270H G570H ------------------------------------------------------------------------------------------------------------------------------------ Target Names AA-ANDROMEDAE HD99111 BD+55D101 ------------------------------------------------------------------------------------------------------------------------------------