5838( 4) - 11/22/95 12:28 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5838 Version: 4 Check-in Date: ********** 1.Proposal Title: The rapidly-evolving hypergiant IRC +10420 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Cool Stars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Kailash Sahu Space Telescope Science Institute CoI: Rene Oudmaijer Kapteyn Laboratory N CoI: Howard Bond Space Telescope Science Institute N ------------------------------------------------------------------------------------ 6. Abstract We propose to undertake a detailed study of the circumstellar envelope of the peculiar F hypergiant IRC +10420, which is a unique object, caught in the short transition phase between the red supergiant and the Wolf-Rayet stage. By performing high spatial resolution imaging in a number of emission lines that probe several parts of the wind we aim to determine the shape and the kinematic structure of the circumstellar envelope. In particular we wish to to investigate whether the geometry of the wind is disc-like or bipolar. The observations will help understanding the change in geometry of the circumstellar envelope as stars evolve from the Red Supergiant Stage to the Wolf-Rayet phase. ------------------------------------------------------------------------------------ 5838( 4) - 11/22/95 12:28 - [ 2] Observations Description ------------------------ The planetary camera images will enable us to identify the spatial extent and structure of the object. To distinguish between the disc and the bi-polar geometry, images need to be taken in different filters as follows: (i) to probe the outflow very close to the star, we will use the HBeta (filter F487N) and PDelta (filter F1042M) lines, (ii) to probe the larger ionised region, we will use the HAlpha (filter F656N), and (iii) to probe the ``lukewarm", lower density part of the envelope, we will use the OI 6300 Angstrom \ line (filter F631N). For continuum observations, we propose broad band images in UBVRI (filters F336W, F439W, F555W, F675W, F791W), to investigate the possible effects of scattering by circumstellar dust with wavelength. We emphasize that this is a bright source with most of the flux concentrated towards the central region, and faint structure extending up to about 2 arc sec. So the integration times are invariably very short, but it is important to take exposures in various filters which probe different parts of the structure. The object is fairly red, B=13, V=11, R=9 and I=8th magnitude. The observed line fluxes of IRC+10420 (Oudmaijer et al. 1994) were used to determine exposure times. As an example, we consider the HAlpha line, for which we propose to use the F656N filter. This filter has a system throughput of 12\ flux from IRC+10420 at HAlpha line is 0.9 * 10^-11 erg cm^-2 s^-1 and the continuum expected is 0.95 * 10^-11 erg cm^-2 s^-1; thus the total expected flux in the filter F656N is ~ 1.85 * 10^-11 erg cm^-2 s^-1. The number of quanta per unit of energy at this wavelength is ~ 3 * 10^11 photons erg^-1. The effective telescope collecting area is 3.9 * 10^4 cm^2. Multiplying all of these together and then dividing by gain of the CCD (14 e^-/DN), we get a total of 15.000 counts over the whole area of the object. Since a significant part of this flux is concentrated to the central region, we would need an integration time of 2 sec which, because of the very high signal to noise, will enable us to see the expected extended structure, without any saturation effects at the central region. The integration times for the other filters vary between 0.11 sec for the F675W filter to 2.5 min for the F336W filter. We aim for high signal-to-noise and propose to obtain 9 exposures in total, in various filters as mentioned above. Including overhead and detector read-out these observations will take slightly less than 1 orbit in total. Thus we request a total spacecraft time of 1 orbit., Real Time Justification ----------------------- No Special Requirements We plan to continue to monitor IRC +10420 using ground- based telescopes. Calibration Justification ------------------------- No Special Requirements Additional Comments ------------------- ------------------------------------------------------------------------------------ 5838( 4) - 11/22/95 12:28 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: STSCI Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5838( 4) - 11/22/95 12:28 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 IRC+10420 STAR RA=19H 26M 48.08S +/-0.1S, 2000.0 V=60 V=11+/-0.5 DEC=+11D 21' 16.8" +/- 0.2" B-V=2+/-0.3 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1950.0 0 0 0 5838( 4) - 11/22/95 12:28 - [ 5] Visit: 01 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 IRC+10420 WFPC2 IMAGE PC1 F656N 6563 1 1.5S POS TARG 0.25,-0.25 ------------------------------------------------------------------------------------------------------------------------------------ 2 IRC+10420 WFPC2 IMAGE PC1 F656N 6563 1 1.5S POS TARG 0.0,0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3 IRC+10420 WFPC2 IMAGE PC1 F487N 4861 1 60S POS TARG 0.25,-0.25 ------------------------------------------------------------------------------------------------------------------------------------ 4 IRC+10420 WFPC2 IMAGE PC1 F487N 4861 1 10S POS TARG 0.0,0.0 ------------------------------------------------------------------------------------------------------------------------------------ 5 IRC+10420 WFPC2 IMAGE PC1 F631N 6300 1 2S ------------------------------------------------------------------------------------------------------------------------------------ 6 IRC+10420 WFPC2 IMAGE PC1 F380W 4000 1 200S ------------------------------------------------------------------------------------------------------------------------------------ 7 IRC+10420 WFPC2 IMAGE PC1 F439W 4390 1 30S ------------------------------------------------------------------------------------------------------------------------------------ 8 IRC+10420 WFPC2 IMAGE PC1 F555W 5550 1 0.5S ------------------------------------------------------------------------------------------------------------------------------------ 9 IRC+10420 WFPC2 IMAGE PC1 F675W 6750 1 0.11S ------------------------------------------------------------------------------------------------------------------------------------ 10 IRC+10420 WFPC2 IMAGE PC1 F1042M 10420 1 0.11S ------------------------------------------------------------------------------------------------------------------------------------ 11 IRC+10420 WFPC2 IMAGE PC1 F656N 6563 1 8S POS TARG 0.5,0.5 ------------------------------------------------------------------------------------------------------------------------------------ 5838( 4) - 11/22/95 12:28 - [ 6] Summary Form for Proposal 5838 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Cool Stars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements POS TARG 0.25,-0.25 POS TARG 0.0,0.0 POS TARG 0.5,0.5 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F656N F487N F631N F380W F439W F555W F675W F1042M ------------------------------------------------------------------------------------------------------------------------------------ Target Names IRC+10420 ------------------------------------------------------------------------------------------------------------------------------------