! File: 3412C.PROP ! Database: PEPDB ! Date: 19-FEB-1994:06:53:52 coverpage: title_1: HIGH RESOLUTION OBSERVATIONS OF NOVA LMC 1991 sci_cat: STELLAR ASTROPHYSICS sci_subcat: HOT STARS proposal_for: GO/DD pi_title: DR. pi_fname: STEVEN pi_mi: N. pi_lname: SHORE pi_inst: COMPUTER SCIENCES CORPORATION pi_country: USA pi_phone: (301) 286-3748 keywords_1: NOVAE, MASS LOSS, NUCLEOSYNTHESIS hours_pri: 7.80 num_pri: 1 pi_position: ASTRONOMER ! end of coverpage abstract: line_1: We propose to obtain low and intermediate line_2: dispersion GHRS observation sof Nova LMC 1991, a unique, super- line_3: Eddington apparently classical nova. With this high S/N data, we will line_4: study the shell dynamics and abundances during the optically thick and line_5: nebular stages. This nova is the intrinsically brightest one ever line_6: observed in the LMC and one of the most luminous ever observed in the line_7: Local Group. ! ! end of abstract general_form_proposers: lname: SHORE fname: STEVEN inst: COMPUTER SCIENCES CORPORATION country: USA ! lname: STARRFIELD fname: SUMNER inst: ARIZONA STATE UNIVERSITY country: USA ! lname: SONNEBORN fname: GEORGE inst: NASA/GSFC country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: All novae during the past three years in the Large line_2: Magellanic Cloud have been observed by our group with IUE. These line_3: include one classical CNO nova that was also a dust-former (N LMC 1988 line_4: #1), an especially fast classical nova (LMC 1988 #2), an O-Mg-Ne nova line_5: (1990 #1), and a recurrent (1990 #2). All of these have displayed line_6: peak optical magnitude of only 10.5 and their luminosities have been line_7: about the Eddington limit for a massive (1.4 solar mass) white dwarf. line_8: However, Nova LMC 1991 presents a spectacular and unique outburst. line_9: During more than one week of our observations in the initial optically line_10: thick stages of the outburst, the luminosity in the 1200 - 3400 A line_11: region alone has been greater than 2E5 L_sun. This is about a factor line_12: of 3 greater than previously observed and strikingly super-Eddington line_13: for even a Chandrasekhar-limit white dwarf with LMC metallicity for line_14: the accreted material. line_16: We are certain of LMC membership for this nova. Observations obtained line_17: at high dispersion with IUE (29 Apr 1991) show the characteristic galactic line_18: halo and LMC absorption at Mg II (there is also a hint of this in low line_19: dispersion C II 1335 and Mg II 2800 data). Thus we are sure that the line_20: luminosity, and not just the apparent brightness, of this nova exceeds line_21: that of any other so far observed in the UV in the LMC (and probably in line_22: the Galaxy). ! question: 3 section: 2 line_1: Novae in the Magellanic Clouds are of prime importance to the study of line_2: the outburst mechanism and development because, with the usual line_3: ambiguity of distance and reddening removed, we can directly determine line_4: energetics and masses. These in turn can be, and have been, used to line_5: calibrate galactic novae of the same outburst class. With LMC 1991 we line_6: have the chance to study the development of a nova that may remain line_7: bright well into the nebular stage. N LMC 1991 is the first line_8: extragalactic nova to go into outburst during HST's lifetime, and it line_9: will provide an invaluable baseline observation for both galactic and line_10: extragalalactic novae. These observations will be important for line_11: understanding the wealth of lower resolution outburst spectra of both line_12: galactic and extragalactic novae obtained with IUE, because the line_13: resolution available with the GHRS is considerably higher than any we line_14: have been able to obtain routinely (most novae have been observed only line_15: with the low dispersion, R=300, mode of IUE). line_17: The nova outburst is modeled via the thermonuclear runaway (TNR) line_18: picture. Matter accreted from a low mass companion on a degenerate line_19: star, a white dwarf for a classical nova, begins nucleosynthesis under line_20: extreme conditions. The release of energy by CNO processing initially line_21: produces no structural changes in the outer envelope of the white line_22: dwarf, but promotes mixing and increases the temperature gradient line_23: while the material remains degenerate. Until the temperature crosses ! question: 3 section: 3 line_1: the threshold for lifting the degeneracy, the rate of nuclear line_2: processing increases with consequent rise in the luminosity until the line_3: Eddington limit is reached. At about this time, an explosion results line_4: as the equation of state changes and subsequently a wind is initiated line_5: from the hot white dwarf envelope. Mass is ejected by a combination line_6: of gas and radiation pressure. line_8: The nebular stage is the most important one for the study of line_9: nucleosynthesis during the outburst. It occurs early enough during line_10: the ejecta expansion that little, if any, ambient material has been line_11: mixed into the ejecta. Therefore the abundances are those that were line_12: frozen in at the end of the TNR phase. In the case of N LMC 1991, we line_13: have the most extreme radiative energy release yet detected in a nova. line_14: It is very important to determine the physical conditions of the line_15: outburst, and especially to obtain accurate abundances and masses for line_16: the ejecta. These are the only window we have into the nuclear line_17: processing region that serves as the site of the outburst. If this line_18: explosion occurred on a low mass white dwarf, it is very hard to line_19: understand how such high luminosity was achieved even during the line_20: optically thick stage of the ejection. If the white dwarf was line_21: massive, then the determination of abundances will place important line_22: constraints on the mixing and structure of the nuclear processing line_23: region during the early stages of the TNR. ! question: 3 section: 4 line_1: line_2: We have arranged continued groundbased coverage with CTIO 4m and 1.5m line_3: echelle and cass. spectrographs (Williams/CTIO), MSO (Dopita), line_4: and ESO (Krautter). We have proposed for ROSAT TOO time (Krautter, line_5: P.I./Heidelberg). Spectra will continue to be obtained with IUE for line_6: as long as possible. line_7: The LSA will be used for all observations to ensure line_8: highest possible S/N ratio and photometric accuracy. The G140L will line_9: be used at two carrousel positions to cover the full 1100 - 1900 A line_10: region. These data will have higher resolution than low dispersion IUE line_11: data with far greater S/N for the later outburst phases. The far-UV line_12: sensitivity of the G140L will provide important information shortward line_13: of Lyman alpha, assisting in placing limits on the temperature and line_14: luminosity of the post-nova degenerate. The G140L spectral region line_15: covers all significant ions for abundance determinations: C III 1175, line_16: Si III 1206, N V 1240, O I 1300, C II 1335, Si IV/O IV/S IV 1400, N IV line_17: 1490, C IV 1550, Ne 1600, He II 1640, O III] 1665, N III] 1750, Si line_18: III] 1890, C III] 1910. Intermediate dispersion observations with the line_19: G200M will provide density diagnosis using the Si III]/C III] ratio. line_20: We will use standard FP-SPLIT with half-stepping. line_22: We propose to add three additional observations, one at N III] 1751, line_23: one at He II 1640 + O III 1661,1667, and one at C IV 1550, ! question: 3 section: 5 line_1: for the purposes of providing density diagnostics, dynamics, line_2: and abundance information. These will be obtained with the G160M line_3: grating. One sequence on the target will suffice for all of the line_4: information necessary for density diagnosis and abundances, line_5: as well as velocity information. ! question: 4 section: 1 line_1: HRS will provide the spectral resolution, sensitivity, line_2: and dynamic range to record the ultraviolet spectra of this nova with a line_3: precision and resolution unobtainable with IUE. The most important line_4: feature of GHRS spectra is their dynamic range, with which we will be line_5: able to observe both strong intercombination and permitted lines, and line_6: weak coronal and trace ionic species lines. We will be able to line_7: use the C III] , N III], and Si III] lines as nebular diagnostics and line_8: dynamics and abundances using the C IV and He II permitted lines. line_9: Even with the lowest (G140L) resolution grating, we will be able to obtain line_10: sufficient resolution to determine abundances and energetics from line line_11: widths well into the nebular stage (if this nova follows the course of line_12: classical galactic novae), long past the stage at which IUE line_13: observations cease to be feasible. Of special importance is the study line_14: of weak high ionization lines of coronal species; these cannot be obtained line_15: with IUE. We will use the N III] and O III] line ratios for the line_16: determination of the electron density independent of the Si III] and C line_17: III] lines. These will also rpovide the necessary information on the line_18: O and N abundances to complement the low resolution observations. line_19: Finally He II and C IV will provide important dynamical Doppler line_20: mapping of the excitation conditions in the ejecta since they are the line_21: only strong permitted lines in the spectrum. ! question: 5 section: 1 line_1: Originally we were requesting two observations, line_2: since at the time we did not know precisely when they would be line_3: scheduled and when the nova would enter the nebular phase. Our latest line_4: (12 June 1991) observations with IUE indicate that this is not line_5: necessary. We also have additional information on the emission line line_6: fluxes and rate of decline, both of which indicate that the novba will line_7: be accessible with HST through August and that we have sufficidnt flux line_8: in the N III] and C IV lines that it is best to take a small increase line_9: in the original one-visit time to obtain medium resolution spectra at line_10: these lines. For the sake of completeness, we add below the original line_11: text. We have resourced the proposal and obtain 7.83 hours of total time. line_12: This is less than the time request originally reviewed by the committee, but line_13: with the added feature that we will obtain more line diagnostics from a single line_14: visit now that we know that the nebular phase has been reached and that we will line_15: only require one pointing at the nova. The rate of decline is sufficiently line_16: slow that we have used the projected flux for mid-August 1991 in making our line_17: estimates. The rate of decline is crrently a factor of 2 per month, line_18: and this is likely to remain constant through the end of Sept. with line_19: what we understand about the envelope dynamics. line_21: Original text -- An interval of several weeks is requested between the initial line_22: and repeat HRS observations to allow for transition to the later nebular stage. line_23: The primary purpose is for abundance determinations. Total request is for ! question: 5 section: 2 line_1: 7.8 hours of HST GHRS observation time including target acquisition for two line_2: visits. Resource (RPSS) calculations yield 4.8 hrs for each time the sequence line_3: is run (lines 11-31) . We will continue monitoring N LMC 1991 with IUE for as line_4: long as it can be observed, but we will require the GHRS observations to line_5: determine any quantitative spectral parameters. We will continue monitoring line_6: with both groundbased and IUE observations in order to revise exposure times or line_7: expected S/N ratio as the nova fades. Presently, we have used a best estimate line_8: of the rate of decline for the nova based on two weeks of IUE observations. line_9: The decline in the UV is always slower than that in the optical and we line_10: anticipate that the nova should be accessible to GHRS observations for about 2 line_11: months and perhaps longer. ! question: 7 section: 1 line_1: The calibration and reduction of the GHRS spectra line_2: will be accomplished with routines developed for the purpose at GSFC. line_3: Newly determined sensitivity tables will be employed in the analysis, line_4: making direct use of SV calibrations. Emission lines will be analyzed line_5: with respect to fluxes, line profiles, and radial velocities. line_6: Corrections for extinction will be applied. The various ionization line_7: stages of key species (C, N, O, Mg, Si, Fe) will be studied to line_8: estimate the excitation, mass, and kinetic energy of the ejecta, line_9: providing a key test of nuclear processing models for the outburst. line_10: Presently undetected coronal lines will be searched for, and fluxes, line_11: or at least upper limits, will be determined. ! question: 9 section: 1 line_1: Shore and Starrfield are involved in one category B line_2: GO proposal for V603 Aql (Friedjung, P.I.). ! question: 10 section: 1 line_1: Reduction software, computers, modeling programs, line_2: preparation of manuscripts, support of publication costs. ! question: 12 section: 1 line_1: We will use interactive target acquisition for N line_2: LMC 1991 using field maps with mirror N2 for the first observation line_3: sequence. The second will be blind-offset, once a pair of guide stars is line_4: obtained. Because novae are transient phenomena, we will use IUE and line_5: groundbased observations to predict the magnitude of the target well before line_6: observations with HST commence. All prerequisite SV tests (low and intermediate line_7: resolution sensitivity calibrations, interactive target acquisitions, etc.) line_8: have already been completed. The expected count rate for N2 at peak brightness line_9: was 17000 cts/sec (using SV calibrations for hot sources). Assuming that the line_10: magnitude is about 15 by the time of observation (mid August), the N2 count line_11: rate is expected to be about 100 cts/sec. The field is sparse enough to line_12: prevent confusion, but there is a sufficient number of guide stars available line_13: for coarse track. ! !end of general form text general_form_address: lname: SHORE fname: STEVEN mi: N. title: DR. category: PI inst: COMPUTER SCIENCES CORPORATION addr_1: CODE 681 GODDARD SPACE FLIGHT CENTER city: GREENBELT state: MD zip: 20771 country: USA phone: (301) 286-3748 ! lname: STARRFIELD fname: SUMNER mi: G. title: DR. category: CON inst: ARIZONA STATE UNIVERSITY addr_1: DEPT. OF PHYS. AND ASTRONOMY addr_2: ARIZ. STATE UNIV. city: TEMPE state: AZ zip: 85287 country: USA phone: (602) 965-7569 ! lname: SONNEBORN fname: GEORGE category: CON inst: LASP/GSFC addr_1: CODE 681 GODDARD SPACE FLIGHT CENTER city: GREENBELT state: MD zip: 20771 country: USA phone: (301) 286-3665 ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: NOVA-LMC-1991 descr_1: CENTRAL OBJECT pos_1: RA = 05H 04M 12.70S+/- 0.1S, pos_2: DEC = -70D 22' 16.2" +/- 0.1", equinox: 1950.0 pm_or_par: NO comment_1: COORDINATES AND FLUXES FOR NOVA comment_2: FROM IUE FLUX FROM SWP41456, comment_3: LWP20210, SCALED BY 1/10 (22 JUNE comment_4: 1991 FLUXES). fluxnum_1: 1 fluxval_1: F-LINE(1240)=3.0E-15 fluxnum_2: 2 fluxval_2: F-LINE(1550)=3.0E-15 fluxnum_3: 3 fluxval_3: F-LINE(2800)=3.0E-15 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: NOVA-LMC-1991 config: HRS opmode: ACQ aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 120S priority: 1 param_1: MAP=END-POINT, param_2: FAINT=5, req_1: INT ACQ FOR 20-31; req_2: CYCLE 1/ 1-33 ! linenum: 20.000 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: G160M wavelength: 1900 num_exp: 1 time_per_exp: 30S priority: 1 param_1: STEP-PATT=4 req_1: CALIB FOR 21; req_2: SEQ 20-22 NO GAP; req_3: CYCLE 1/ 20-22 comment_1: WAVELENGTH CALIBRATION LINE 21-22 comment_2: TO INCLUDE SPECTRUM Y BALANCE. ! linenum: 21.000 targname: NOVA-LMC-1991 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G200M wavelength: 1900.0 num_exp: 1 time_per_exp: 100M s_to_n: 10 fluxnum_1: 2 priority: 1 param_1: STEP-PATT=4, param_2: FP-SPLIT=TWO param_3: COMB=TWO ! linenum: 22.000 targname: NOVA-LMC-1991 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G160M wavelength: 1750.0 num_exp: 1 time_per_exp: 100M s_to_n: 10 fluxnum_1: 2 priority: 1 param_1: STEP-PATT=4, param_2: FP-SPLIT=TWO param_3: COMB=TWO ! linenum: 31.000 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: G160M wavelength: 1400 num_exp: 1 time_per_exp: 30S priority: 1 param_1: STEP-PATT=4 req_1: CALIB FOR 32; req_2: SEQ 31-33 NO GAP; req_3: CYCLE 1/ 31-33 comment_1: WAVELENGTH CALIBRATIONS LINES 32-33, comment_2: TO INCLUDE SPECTRUM Y BALANCE. ! linenum: 32.000 targname: NOVA-LMC-1991 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G160M wavelength: 1240 num_exp: 1 time_per_exp: 100M s_to_n: 15 fluxnum_1: 1 priority: 1 param_1: STEP-PATT=4, param_2: FP-SPLIT=TWO param_3: COMB=TWO ! linenum: 33.000 targname: NOVA-LMC-1991 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G160M wavelength: 1640.0 num_exp: 1 time_per_exp: 100M s_to_n: 10 fluxnum_1: 2 priority: 1 param_1: STEP-PATT=4, param_2: FP-SPLIT=TWO param_3: COMB=TWO ! ! end of exposure logsheet ! No scan data records found