8671( 4) - 09/26/00 13:31 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8671 Version: 4 Check-in Date: 26-Sep-2000 13:30:44 1.Proposal Title: STIS Observations of a Magellanic Cloud Nova in Outburst ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 9 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Steven Shore Indiana University System CoI: Dr. H. Bond Space Telescope Science Institute N CoI: Dr. R. Downes Space Telescope Science Institute N CoI: Prof. A. Evans Keele University N CoI: Dr. M. della Valle University of Padua N CoI: Prof. R. D. Gehrz University of Minnesota N CoI: Prof. P. H. Hauschildt University of Georgia N CoI: Prof. J. Krautter Landessternwarte, Heidelberg N CoI: Prof. S. Starrfield Arizona State University N CoI: Prof. C. F. Woodward University of Wyoming N ------------------------------------------------------------------------------------ 5. Abstract We propose target-of-opportunity observations of a classical nova in the Magellanic Clouds in the early stages of its outburst. Nova outbursts are thermonuclear runaways triggered by accretion onto a white dwarf within a close binary system. As such, nova systems are a possible evolutionary stage on the way to a final accretion -induced collapse and a Type Ia supernova explosion. The study of how the accreted mass is mixed, the nuclear processing that occurs during the outburst, the energetics of the explosion, and the determination of ejecta masses constrain models for SNe Ia progenitors. The ultraviolet (UV) spectrum provides fundamental and unique information on the expanding nova ejecta. We propose to obtain spectrophotometric and line-profile information at sufficient resolution with STIS to determine the abundances and mass of the ejecta as a function of position in the nebula and, thereby, obtain a comprehensive picture of the energetics of the outburst, which can be compared to multidimensional hydrodynamic studies of nova explosions. Because novae are hot and have lines from chemical elements that are only detectable in the UV, the STIS UV capability is crucial for an analysis of nova ejecta. The nova will also provide a background source for study of the Galactic and MC interstellar media along the line of sight to the outburst. ------------------------------------------------------------------------------------ 8671( 4) - 09/26/00 13:31 - [ 2] Observations Description ------------------------ We propose to obtain two sets of observations for either an LMC or SMC nova during the first five months of outburst. We expect at least one MC nova to occur during Cycle 9, based on historical ground-based observations and EROS and MACHO discovery statistics. Our estimated exposure times for MC novae in outburst are based on our IUE spectra of LMC 1990\#1 and our recent STIS observations of the Galactic nova V382 Vel 1999. An IUE spectrum taken within one week of discovery and at short-wavelength UV maximum (SWP 38042) gives a range of 0.2 cts s^-1 for Lambda <= 1400 Angstrom to 0.03 cts s^-1 at longer wavelengths using the E140MNull. Similar rates are obtained for the E230M for the long- wavelength spectrum. The spectrum of LMC 1990\#1 showed strong P Cyg absorption at Si IV and C IV, which we will completely resolve with E140MNull. The improvement in resolution will eliminate the resolution problem that plagued the IUE analysis (see Vanlandingham et al.\ 1999). A nebular spectrum (SWP 38136) obtained 200 days after outburst implies a peak count rate of 0.1 cts s^-1 at N V and a mean count rate of 0.01 cts s^-1 for the 1200-1700 Angstrom\ wavelength range. At this late stage, the Ne III transition near 1920 Angstrom\ can be observed with a similar count rate using E230MNull. For the UV maximum spectra of the CO nova LMC 1995 (SWP 54568 and LWP 30570), E140M yields a mean count rate of 0.1 cts s^-1 and E230M gives 5 cts s^-1. This spectrum was taken during the optically thick phase before the nebular lines appeared and represents the minimum in the early short- wavelength emission. The late-time spectra have similar count rates to those observed for LMC 1990\#1. These estimates are confirmed by our very recent STIS observations of V382 Vel. Therefore, for an MC nova, we expect that an exposure time of 10, 000 sec should produce a S/N of at least 10 per pixel (full resolution) or about 30 for 10-point binning (which still provides a 40 km s^-1 velocity resolution, clearly sufficient for our purposes. For the second observation, a S/N of 10 is achieved with a 20, 000 sec exposure. We therefore require total exposure times of approximately 30, 000 sec for the first epoch for a total of 6 orbits exposure time for the first set of observations; and 60, 000 sec or 12 orbits for the second epoch. The grand total is 18 orbits for 3 medium-resolution echelle spectra on each of two epochs (since the E230M grating requires two tilts to cover the complete UV spectrum). We will be able to observe line profiles for all important species between 1100 and 3000 Angstrom\ with sufficient S/N to obtain line profiles for the ejecta during the earliest stages of the outburst. These will provide essential data for comparisons with the hydrodynamic calculations. Our experience with LMC 1992, using the GHRS, and V382 Vel with STIS, shows that we will also be able to obtain interstellar line profiles, which will be useful for studying the important lines of Si IV, C IV, and N V in the Galactic halo (Schwarz et al.\ 1998) in the line of sight to the nova (see, e.g., Mg II and C IV profiles shown in Fig. 3). The STIS echelle mode has a great advantage over our previous GHRS observations in providing simultaneous coverage over a broad wavelength range with great efficiency. In our study of V1974 Cyg, for example, we were unable to observe several key lines because of the limitations of time and spectral coverage available with the medium-dispersion gratings. We also lost data on LMC novae because of instrument failures. Our recent STIS observations of V382 Vel confirm that we will be able to observe all key transitions covering the three principal ionization stages of the CNO elements, plus weak and interstellar lines that were too faint to detect with the GHRS. This will provide the definitive data set for multiwavelength observations of an extragalactic nova in outburst. We have organized an international team to conduct ground-based and satellite observations for all novae observed with STISNull. Cooperating astronomers include A. Evans (Keele; IR), M. della Valle (ESO, optical), J. Krautter (Heidelberg, optical and IR), R. Gehrz (U. Minn., IR), S. Starrfield (ASU, optical), and C. Woodward (U. Wy., IR and optical). On the discovery of a Magellanic Cloud nova, our group will immediately begin ground-based observations to determine the t_3 time and plan our observing strategy. The European Co- I's will provide immediate response in the southern hemisphere through proposals to ESONull. Our team has approved TOO proposals for Chandra and FUSE observations, and we were successful in obtaining time at ESO for coordinated optical and IR observations of V382 Vel. Data analysis will proceed in a similar fashion as described in our earlier papers on multiwavelength observations of novae in outburst (Shore et al.\ 1993, 1996, 1997; Schwarz et al. 1997a, 1997b, 1998; Vanlandingham et al.\ 1996, 1997, 1998) and our current analysis of V382 Vel. For the study of the spectra taken in the intermediate stage, we will use our non- LTE, line-blanketed, spherical, stellar atmosphere code PHOENIX (Hauschildt et al.\ 1997, and references therein) to model the earliest development of the UV spectra. We have employed this approach for the analysis of our IUE and GHRS observations with considerable success. We will also use PHOENIX to compute synthetic spectrophotometry, in order to obtain temperatures and luminosities, as well as provide theoretical continua for photoionization modeling. The nebular analysis will be conducted using CLOUDY, combined with a robust optimization procedure ( MINUIT: Vanlandingham et al.\ 1996, 1997, 1998). In summary, we will need 18 orbits distributed over two epochs to observe one MC nova in early stages of outburst. We expect one MC nova will likely occur during Cycle 9. Real Time Justification ----------------------- STScI will be notified at the time of optical maximum, and the sequence will be initiated when the nova has declined by Delta V = 3 mag from peak (i.e., the t_3 time, which is directly related to the rate of UV rise). Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8671( 4) - 09/26/00 13:31 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 3 MC-NOVA STAR, CLASSICAL NOVA RA=05H 25M 1.76S +/- 0.1S, DEC=- J2000 F-CONT(2000)=3+/-2e-13 70D 14' 19.5" +/- 0.1", PLATE- E(B-V) = 0.2+/-0.1 ID=05ZW V = 14.0+/-0.5 Coordinate Source: IMAGE_TIED_TO_GSC_FRAME Comments: V~14 at first epoch, V~16 at second epoch Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 0.0 0.0 0.0 8671( 4) - 09/26/00 13:31 - [ 4] Visit: 01 Visit Priority: Visit Requirements: GROUP 1-2 WITHIN 3 D SCHED 70% BETWEEN 17-Aug-2000 AND 23-Aug-2000 On Hold Comments: Additional Comments: First visit -- after optical maximum at around t_3 FIRST visit should occur before nebular stage. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 MC-NOVA STIS/C ACQ F25ND3 MIRROR 1 15 S CD Comments: using V382 Vel spectrum at age 30 days, assumed V=14 ------------------------------------------------------------------------------------------------------------------------------------ 20 MC-NOVA STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 1 S CD K 6 Comments: using V382 Vel spectrum at age 30 days, assumed V=14 ------------------------------------------------------------------------------------------------------------------------------------ 30 MC-NOVA STIS/F ACCUM 0.2X0.0 E140M 1425 1 2000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 40 MC-NOVA STIS/F ACCUM 0.2X0.0 E140M 1425 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 50 MC-NOVA STIS/F ACCUM 0.2X0.0 E140M 1425 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 60 MC-NOVA STIS/F ACCUM 0.2X0.0 E140M 1425 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 70 MC-NOVA STIS/F ACCUM 0.2X0.0 E140M 1425 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 8671( 4) - 09/26/00 13:31 - [ 5] Visit: 02 Visit Priority: Visit Requirements: BETWEEN 17-Aug-2000 AND 23-Aug-2000 GROUP 1-2 WITHIN 3 D SCHED 70% 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 MC-NOVA STIS/C ACQ F25ND3 MIRROR 1 15 S CD Comments: using V382 Vel spectrum at age 30 days, assumed V=14 ------------------------------------------------------------------------------------------------------------------------------------ 20 MC-NOVA STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 1 S CD K 6 Comments: using V382 Vel spectrum at age 30 days, assumed V=14 ------------------------------------------------------------------------------------------------------------------------------------ 30 MC-NOVA STIS/N ACCUM 0.2X0.0 E230M 2707 1 2000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 40 MC-NOVA STIS/N ACCUM 0.2X0.0 E230M 2707 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 50 MC-NOVA STIS/N ACCUM 0.2X0.0 E230M 1978 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 60 MC-NOVA STIS/N ACCUM 0.2X0.0 E230M 1978 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 8671( 4) - 09/26/00 13:31 - [ 6] Visit: 03 Visit Priority: Visit Requirements: GROUP 3-4 WITHIN 4 D SCHED 30% AFTER 01 BY 87 D TO 101 D On Hold Comments: Additional Comments: Second visit, after about 100-120 days -- nebular spectrum, should be between November 15-30 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 MC-NOVA STIS/C ACQ F28X50L MIRROR 1 2.1 S CD P Comments: using V382 Vel spectrum at age 150 days, assumed V=14-17 ------------------------------------------------------------------------------------------------------------------------------------ 20 MC-NOVA STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 3.0 S CD K 6 Comments: using V382 Vel spectrum at age 150 days, assumed V=14-17 ------------------------------------------------------------------------------------------------------------------------------------ 30 MC-NOVA STIS/F ACCUM 0.2X0.0 E140M 1425 1 2000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 40 MC-NOVA STIS/F ACCUM 0.2X0.0 E140M 1425 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 50 MC-NOVA STIS/F ACCUM 0.2X0.0 E140M 1425 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 60 MC-NOVA STIS/F ACCUM 0.2X0.0 E140M 1425 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 8671( 4) - 09/26/00 13:31 - [ 7] Visit: 04 Visit Priority: Visit Requirements: SCHED 30% GROUP 3-4 WITHIN 4 D On Hold Comments: Additional Comments: Second visit, after about 100-120 days -- nebular spectrum Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 MC-NOVA STIS/C ACQ F28X50L MIRROR 1 2.1 S CD P Comments: using V382 Vel spectrum at age 150 days, assumed V=14-17 ------------------------------------------------------------------------------------------------------------------------------------ 20 MC-NOVA STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 3.0 S CD K 6 Comments: using V382 Vel spectrum at age 150 days, assumed V=14-17 ------------------------------------------------------------------------------------------------------------------------------------ 30 MC-NOVA STIS/N ACCUM 0.2X0.0 E230M 1978 1 2000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 40 MC-NOVA STIS/N ACCUM 0.2X0.0 E230M 1978 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 50 MC-NOVA STIS/N ACCUM 0.2X0.0 E230M 1978 1 1500 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 55 MC-NOVA STIS/N ACCUM 0.2X0.0 E230M 1978 1 1000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 60 MC-NOVA STIS/N ACCUM 0.2X0.0 E230M 2707 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 70 MC-NOVA STIS/N ACCUM 0.2X0.0 E230M 2707 1 3000 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 8671( 4) - 09/26/00 13:31 - [ 8] Summary Form for Proposal 8671 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F25ND3 0.2X0.06 F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GROUP 1-2 WITHIN 3 D SCHED 70% BETWEEN 17-Aug-2000 AND 23-Aug-2000 BETWEEN 17-Aug-2000 AND 23-Aug-2000 GROUP 1-2 WITHIN 3 D SCHED 70% GROUP 3-4 WITHIN 4 D SCHED 30% AFTER 01 BY 87 D TO 101 D SCHED 30% GROUP 3-4 WITHIN 4 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M E230M ------------------------------------------------------------------------------------------------------------------------------------ Target Names MC-NOVA ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 2707 1978 ------------------------------------------------------------------------------------------------------------------------------------