Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4844c Report Date: 09-May-96:20:01 Version: ********** Check-in Date: ********** 1.Proposal Title: CENTRAL STARS OF PLANETARY NEBULAE: CYCLE3MED ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GTO/FOC 1254 Sub Category SUBLUMINOUS STARS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Ir. T. M Kamperman SRON SPACE RESEARCH UTRECHT NETHERLAND 3130535715 PROGRAM COORDINATOR ------------------------------------------------------------------------------------ 7. Abstract It has proved impossible to detect the very hot exciting stars of some planetary neblae from the ground. This is probably because these stars emit a great many ionizing photons for each visible quantum. The ionized nebula is therefore so extensive that the nebular emission, both line and continuum, completely dominate the visual continuum emission of the central star, which becomes lost in the noise. Observing above the atmosphere increases the possibility of detection of these central star by a factor of at least 400. A factor ~ 100 because the light of the central star is within an image of. 1" instead of the ~ 1" ground seeing limitation allowing better discrimination of the star against the diffuse nebular continuum and a further factor ~ 4 occurs because the star is that much brighter, relative to the nebula, in the ultraviolet than it is in the visible. With the spherical abberation of HST, the above mentioned factor of 100 is reduced to about 15, but as the UV adventage remains, detectability is still several magnitudes beyond groundobservations. ------------------------------------------------------------------------------------ 8. Scientific Key Words: PLANETARY NEBULAE, HOT CENTRAL STARS. ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 5.30 par: 0 10. Num targs pri: 5 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4844c PI: Ir. T. M Kamperman Proposal Title: CENTRAL STARS OF PLANETARY NEBULAE: CYCLE3MED ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Prof. S. R Pottasch GRONINGEN, UNIVERSITY OF NETHERLANDS X Dr. A. A Zijlstra GRONINGEN, UNIVERSITY OF NETHERLANDS X Dr. N. Walton UNIVERSITY COLLEGE LONDON ENGLAND X T. M Kamperman SRON SPACE RESEARCH UTRECHT NETHERLANDS X ------------------------------------------------------------------------------------ 3. Description of proposed observations. In July '91 exposures have been made though different narrow band UV filters of the nebula NGC7027. Fluxes through 278 and 210 nm filters can be well explained, but the one through the 130 nm. filter is not compatible with existing extinction models for 7027. Current approach is to continue this study by using the FOC- prism mode to get an extinction profile in the UV (IUE cannot discriminate between nebula and star). As reference PN stars also NGC 2440 (expected low extinction, as 7027) and NGC 6537 (high extinction) will be measured. At least the comparison of the three should give better values of the densities of the PN' and thus a better understanding in what respect, for instance, PHA's have to be incorporated in the model. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The combination of ultraviolet sensitivity and the sharp central peak in HST's PSF will result in a much higher detectability of central stars. Where the detectability ratio HST/ground was originally at least 400, the ratio is still about 70 in the same observation time. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. No special scheduling requests. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. All proposers have access to state-of-the-art data analysis facilities at their home institutions. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. All objects have been GASP-ed at the STSCI. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. In CYCLE 1 NGC7027 was observed in a very small field. There is little doubt anymore wheter this was a correct pointing. The physics of the PN is the underlying reason for this proposal. ------------------------------------------------------------------------------------ 9. Description of previous HST work. All three institutes have sufficient resources to support this project ------------------------------------------------------------------------------------ 11. Address Information Page 3 Name: T. M KAMPERMAN Category: PI Institution: SRON SPACE RESEARCH UTRECHT Address: SORBONNELAAN 2 3584 CA City: UTRECHT State: Zip Code: Country: NETHERLANDS Telephone: 3130535715 Telex (or e-mail): NL 47224 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4844c [ 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 NGC7027 A,184 RA=21H07M1.7S+/-.5S, J2000 V=10 EXT 1 V=8.6+/-.2 DEC=-42D14'9.4"+/-2", 2 SURF(V)=14.4+/-1. 3 F(4861)=6.8+/-1.0E-11 4 SURF(1500)=7.6+/-2.E-16 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4844c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 DEFINE # FOC/96 IMAGE 512X512 PRISM1, 1 60M 3 1 PRISMOB -DF F195W S ------------------------------------------------------------------------------------------------------------------------------------ 2 USE NGC7027 CYCLE 3 PRISMOB S ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4844c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOC/96 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GTO/FOC ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 5.30 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category SUBLUMINOUS STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements PRISM1,F195W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC7027 ------------------------------------------------------------------------------------------------------------------------------------