Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 2955c Report Date: 09-May-96:17:40 Version: ********** Check-in Date: ********** 1.Proposal Title: UV IMAGING AND SPECTROSCOPY OF S ANDROMEDAE IN M31 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID INTERSTELLAR MEDIUM GO/DD Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Robert A. Fesen DARTMOUTH COLLEGE USA 603-646-2949 ASSISTANT PROFESSOR ------------------------------------------------------------------------------------ 7. Abstract We recently discovered the long sought after remnant of the famous historical supernova, commonly known as S Andromedae, which occurred in 1885 in the bulge of M31. The remnant is detected optically as a dark spot of Fe I absorption at precisely the observed position of the SN event. Our detection shows that S And contains a large quantity of cold iron freely expanding at velocities up to 5000 km/s, consistent with its historical Type I classification. The remnant's inferred diameter is 0.3 - 0.5 arcsec. We propose to obtain UV FOC imaging and FOS spectroscopy of S And's remnant. From observed absorption line profiles it should be possible to determine directly density and composition as a function of radius in the freely expanding ejecta. This is a uniquely powerful observation made possible by HST's UV capability. It is important to establish first epoch observations of S And's evolving remnant at the earliest opportunity. ------------------------------------------------------------------------------------ 8. Scientific Key Words: SUPERNOVA REMNANT, SUPERNOVAE, M31 ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 3.50 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS FOC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 2955c PI: Dr. Robert A. Fesen Proposal Title: UV IMAGING AND SPECTROSCOPY OF S ANDROMEDAE IN M31 ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Dr. Robert A. Fesen DARTMOUTH COLLEGE USA Dr. Andrew J. Hamilton UNIVERSITY OF COLORADO, BOULDER USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. IN ORDER TO DETERMINE S AND'S PRECISE SIZE AND LOCATION, WE WILL OBTAIN AN FOC IMAGE TAKEN THROUGH THE F231M + F220W FILTER COMBINATION WHICH YIELDS A NEARLY IDEAL BANDPASS FOR OUR PURPOSE TOGETHER WITH EXCELLENT SUPPRESSION OF M31'S BULGE LIGHT ABOVE 2600 A. THIS FILTER COMBO HAS A PEAK TRANSMISSION AT 2340 A WHICH IS VERY CLOSE TO THE STRONG 2343, 2374, AND 2382 FE II LINES. (CF. FOC HANDBOOK, PG. 74). WE WILL OBTAIN A 100 MINUTE EXPOSURE WITH THE FOC AT F/96. THIS IMAGE WILL YIELD S AND'S ANGULAR SIZE AND TELL WHETHER THERE ARE ANY SMALL NEARBY DUST FEATURES TO WORRY ABOUT. WE WILL USE THE FOS/RD WITH THE 1.0" PAIR APERTURES AND G270H GRAING TO OBTAIN A SPECTRUM OF THE 2230-3309 A REGION FOR BOTH THE OBJECT (S AND) AND THE BULGE (BACKGROUND SKY). THESE SPECTRA WILL PERMIT THE DETECTION OF THE REMNANT'S FE II RESONANCE LINES AT 2343, 2383, 2586, AND 2599 A PLUS FE I RESONANCE LINES AT 2483, 2522, AND 2719 A. DUE TO THE ONE SIDED TAN S AND IS RECEIVING FROM M31'S BULGE, WE EXPECT THAT THE REMNANT'S FE I LINES WILL BE BLUESHIFTED, WHILE THE FE II LINES WILL BE REDSHIFTED. DUE TO THE `GIMP' PROBLEM, THE 2 HR TOTAL EXPOSURE TIME WILL BE BROKEN INTO MANY SHORT, 4 MIN EXPOSURES TO MITIGATE THE GIMP PROBLEM WHICH IS SEVERE FOR THE 1.0'' APERTURES. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. UV absorption observations of the 0.5 arcsec diameter remnant of S And use HST's UV capilities to great advantage. While some Fe I lines can be observed from the ground, all the Fe II resonance lines lie in the UV. IUE's relatively low sensitivity and large 3 arcsec aperture make spectral observations with IUE only marginal. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Imaging with the FOC: Using the F231M + F220W filter combination, we estimate over 1000 cts on M31's bright nucleus and around 750 cts at S And's location in a 100 min exposure per 0.1'' resolution element. We estimate a S/N of around 25 at S And's psoition. FOS SPECTRA: At 2500 A, flux at S And's bulge position is 4E- 15 ergs/s cm2 A. Using the FOS/RD digicon and the G270H grating, a total exposure time of 120 minutes in star-sky mode (i.e. 60 min on each) will result in a total of around 4000 cts on target and a S/N of 50 at 2500 A. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. N/A Page 3 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The FOC image will be useful in determining S And's precise location but not needed for offset positioning of the 1.0 arcsec aperture pairs of the FOS/RD. S And's position will be measured relative to a 14th mag star to the SW. The FOC image be also searched for evidence of other small sysmetric absorption features. We will collaborate with GTO programs obtaining WFC or FOC images of M31's bulge to help to distinguish Fe II absorbing features (other old Type I SNRs) from bulge dust clouds. FOS spectral data reduction will include accurate flux and wavelength calibrations, and equivalent width and profile measurements for both Fe I and Fe II absorption lines detected. HST data will be combined with optical ground-based Fe I spectral data to construct a detailed observational picture LINE_14: of the remnant's composition and ionization structure as a function of radius in the ejecta. These data will then be compared to deflagration and detonation exploding white dwarf models. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. We note that a GTO program (#1044) is planning to observe S And. Their goal, however, is the detection of the remnant through emission lines, not absorption lines, using the FOS/BL. Our discovery of the remnant supersedes their observational search and the stated exposure time for this GTO program (700 sec) is quite inadequate to detect any of the Fe I or Fe II absorption features. Moreover, the chosen grating (G130H) misses the crcial lines of Fe II at 2380 and 2600 A. ------------------------------------------------------------------------------------ 9. Description of previous HST work. NO ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The resources provided by Dartmouth include computer time and programming assistance for data reduction and analysis: software development, graphics, and post-processing will be carried out at the home institution. ------------------------------------------------------------------------------------ 11. Address Information Name: ROBERT A FESEN Category: PI Institution: DARTMOUTH COLLEGE Address: DEPARTMENT OF PHYSICS AND ASTRONOMY WILDER HALL City: HANOVER State: NH Zip Code: 03755 Country: USA Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ Name: ROBERT A. FESEN Category: PI Institution: DARTMOUTH COLLEGE Address: DEPARTMENT OF PHYSICS AND ASTRONOMY WILDER LAB City: HANOVER State: NH Zip Code: 03755 Country: USA Telephone: 603-646-2949 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 2955c [ 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 S-AND-FIELD EXT-MEDIUM; DARK RA = 00H 39M 58.84S +/- 1950 BKG 1 SURF(2500) = 4 +/-1 E-15 SN1885 M31 NEBULA; SN 0.2S, DEC = +40D 59' 38.5" +/- 0.5" Comments: V FLUX NOT GIVEN BECAUSE WE WILL NOT ACQUIRE DIRECTLY ON OUR TARGET ------------------------------------------------------------------------------------------------------------------------------------ 2 S-AND-OFFSET STAR; OFFSET STAR RA = 00H 39M 49.4S +/-0.4S, 1950 BKG 1 V = 12.32 +/- 0.1 -STAR DEC = +40D 59' 24.0" +/-0.5" Comments: CLOSER BUT FAINTER OFFSET STAR CAN BE CHOSEN IF NEEDED. ------------------------------------------------------------------------------------------------------------------------------------ 3 S-ANDROMEDAE EXT-MEDIUM; DARK TBD-EARLY, 1950 BKG 1 SURF(2500) = 4 +/-1 E-15 SN1885-SNR NEBULA; SN RA = 00H 39M 58.84S +/- 0.2S, DEC = +40D 59' 38.5" +/-0.5" Comments: COORDINATES MAY BE UPDATED BASED ON FOC IMAGES ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 2955c [ 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 S-AND-FIELD FOC/96 IMAGE 512X512 F231M, 2340 10 600S 15 1 1 CYCLE 1 F220W 6000S Comments: M31'S NUCLEUS MAY PRODUCE 120 CTS PER 0.1'' ELEMENT DURING EACH 20 MIN EXPOSURE. ------------------------------------------------------------------------------------------------------------------------------------ 2 S-AND- FOS/RD ACQ/ 4.3 MIRROR BRIGHT=330000 1 3.0S 1 CYCLE 1 OFFSET-STAR BINARY FAINT=3300 ONBOARD ACQ FOR 3 Comments: STAR FOR USE IN BLIND OFFSET FOR FOS OBS. ------------------------------------------------------------------------------------------------------------------------------------ 3 S- FOS/RD ACCUM 1.0- G270H 2400 STEP-PATT=STAR- 1 7200S 10 1 1 CYCLE 1 ANDROMEDAE PAIR SKY Comments: POSITION MIGHT BE UPDATED BASED ON FOC IMAGE. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 2955c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOC/96 FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACQ/BINARY ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT FAINT STEP-PATT ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/DD ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 3.50 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 1 CYCLE 1; ONBOARD ACQ FOR 3; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F231M,F220W MIRROR G270H ------------------------------------------------------------------------------------------------------------------------------------ Target Names S-AND-FIELD SN1885 M31 S-AND-OFFSET-STAR S-ANDROMEDAE SN1885-SNR ------------------------------------------------------------------------------------------------------------------------------------