! File: 4416C.PROP ! Database: PEPDB ! Date: 22-FEB-1994:10:59:30 coverpage: title_1: THE HOT STELLAR COMPONENT IN THE CENTERS OF M31 AND M32: title_2: CYCLE3 HIGH sci_cat: GALAXIES & CLUSTERS sci_subcat: STELLAR POPULATIONS proposal_for: GO pi_fname: HENRY pi_mi: C. pi_lname: FERGUSON pi_inst: UNIVERSITY OF CAMBRIDGE pi_country: ENGLAND hours_pri: 11.64 num_pri: 2 foc: Y off_fname: DONALD off_lname: LYNDEN-BELL off_title: DIRECTOR off_inst: 8014 off_addr_1: THE OBSERVATORIES off_addr_2: MADINGLEY ROAD off_city: CAMBRIDGE off_zip: CB3 0HA off_country: ENGLAND off_phone: (0223) 337548 ! end of coverpage abstract: line_1: We propose to construct a far-UV color-magnitude diagram for the line_2: point sources detected in FOC images of the centers of M31 and M32. line_3: These data will be used, in conjunction with spectroscopy obtained line_4: by the Hopkins Ultraviolet Telescope, to provide constraints line_5: on the mix of stars responsible for the far-UV emission in old, line_6: metal-rich stellar populations. Our inference from the existing HUT line_7: and FOC data is that the resolved sources are mostly low-mass PAGB stars. line_8: If so, our observations will provide the first direct estimates of line_9: the PAGB star mass distribution, and will provide important insight line_10: into the differences in the evolution of the stellar populations in line_11: these two galaxies, the amount of mass-loss among the AGB progenitor line_12: stars and evolution along the PAGB. By combining our observations line_13: through different filters, we will be able to assess the emission-line line_14: contribution and search for variability. Comparison with the HUT line_15: data will allow a precise estimate of the contribution to the far-UV line_16: light from PAGB stars of different mass, and will allow a more line_17: precise determination of the spectral-energy distribution of the line_18: remaining unresolved population. ! ! end of abstract general_form_proposers: lname: FERGUSON fname: HENRY title: PI mi: C. inst: UNIVERSITY OF CAMBRIDGE country: UNITED KINGDOM esa: Y ! lname: KING fname: IVAN mi: R. inst: UC-BERKELEY country: USA ! lname: DAVIDSEN fname: ARTHUR mi: F. inst: JOHNS HOPKINS UNIVERSITY country: USA ! lname: STANFORD fname: S. ADAM inst: UC-BERKELEY country: USA ! lname: DEHARVENG fname: JEAN-MICHEL inst: CNRS LABORATOIRE D'ASTRONOMIE SPATIALE country: FRANCE esa: Y ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: The FOC will be used in f/96 mode with the F275W and F175W filters line_2: in zoom mode (0.022 X 0.044 arcsec pixels) to obtain images of line_3: the M31 bulge and of M32 in the far UV. We strongly prefer to use line_4: f/48 mode if it becomes available again for imaging. line_6: We originally proposed to obtain photometry accurate to 10% line_7: in the F150W and F220W filters to the detection limit of the line_8: existing f/48 F175W image. This is not possible in the f/96 mode. line_9: Instead, we aim to obtain F275W images sufficient to get line_10: S/N ~ 10 on a T=20000K star with STMAG=21 in the F175W bandpass. line_11: The additional shorter F175W exposures will be combined with line_12: the existing f/48 F175W images to obtain nearly the same S/N, line_13: and will also serve to test the calibration. line_15: We wish to keep the orientation the same as the previous f/48 line_16: F150W observations, so that we do not lose stars off the corners line_17: of the field. line_19: Note that if the observations are to be carried out in f/48 line_20: mode, some of our requirements will change, and this could line_21: potentially affect the scheduling of the observations. In line_22: particular, the ORIENTations will likely be different, and line_23: we would require DARK time for F150W observations. ! question: 4 section: 1 line_1: The stars we propose to observe are detectable only in the far-UV. The line_2: integrated spectra of M31 and M32 have been measured by IUE line_3: \acite{Johnson79; Welch 1982; Burstein 1988}. M31 was observed by by line_4: HUT \acite{Ferguson 1991 ApJ; Ferguson Davidsen submitted}. line_5: Low-resolution far-UV images were obtained from a sounding rocket line_6: \acite{BCHHOS85} and more recently from the UIT \acite{O'Connell 1991 line_7: Stellar; O'Connell 1992 ApJ}. No resolved sources were detected in line_8: these images. Far-UV images have been taken in 1991 with HST. line_9: In the M31 F175W image \acite{King 1992 ApJ}, 137 sources were detected line_10: in the $44 \times 44\arcsec$ FOC $f/48$ field of view. Estimates from line_11: this image suggest that resolved sources provide roughly 15\% of the line_12: total flux at 1750\ang. More recent images were obtained at 1500\ang line_13: with the F130LP+F150W filters \acite{Bertola 1992}. These images were line_14: not as deep as expected, and the field of view was $22 \times line_15: 22\arcsec$, so fewer sources were detected. Preliminary estimates from line_16: these images suggest that the resolved sources contribute a much larger line_17: proportion of the far-UV flux \acite{Buson 1992}. line_19: While we expect the FOC calibrations now planned for Cycle 2 to resolve line_20: much of the discrepancy about the contribution of the resolved sources line_21: to the total far-UV flux, the wavelength coverage and depth of the line_22: existing images is insufficient to constrain the temperature line_23: distribution of the point sources and the amount of emission-line ! question: 4 section: 2 line_1: contamination. A color-magnitude diagram with a wide UV baseline will line_2: provide the necessary constraints, and will allow for the first time a line_3: direct estimate of the PAGB star mass distribution. line_5: For comparison with the existing F175W image, there is are great line_6: advantages to to carrying out these observations in f/48 mode if line_7: it becomes possible to do so. ! question: 4 section: 3 line_1: To measure the PAGB-star mass distribution (assuming that is what most line_2: of the sources are), we will try to assign stars to evolutionary tracks line_3: like those shown in Fig. 3. To do this adequately for a large enough line_4: sample, we desire photometric accuracy better than 0.1 mag down to an line_5: ST magnitude $m = 21.0$. This should be sufficient to probe the mass line_6: distribution down to the Schoenberner 0.546 solar-mass track, and should line_7: allow detection to even lower masses. line_9: It is not possible to achieve this desired sensitivity in f/96 mode line_10: within the time allocated by the TAC. In f/96 mode, the best combination line_11: of temperature discrimation and sensitivity can be obtained by using line_12: the F275W and F175W filters. The F175W observations will serve to line_13: calibrate and increase the S/N of the existing f/48 images. The F175W line_14: images are not quite as deep as the F275W images. line_16: The ingredients in the exposure time calculation are as follows: line_17: Source spectral Energy distribution: line_18: - We have used a Kurucz (1992) model atmosphere with T_eff = 20000K line_19: and log(g) = 4.5. For a source of this temperature detected at line_20: 1 count/s in the f/48 F175W filter, the count rate would be 1.25 line_21: and 3.02 in the f/96 F175W and F275W filters, respectively. line_22: Diffuse UV background + redleak: line_23: - For M31 we used a spectral-energy distribution compiled by ! question: 4 section: 4 line_1: Burstein (1992); for M32 we used the IUE SED from Burstein (1988), line_2: joined at 3300A to the "cold-E" 15Gyr model of Rocca-Volmerange & line_3: Guiderdoni (1987). To normalize, we estimated the mean background line_4: (after subtracting dark-count) within the central 15 arcsec diam line_5: (3.2e-3 counts/pixel) for M31; 2.9e-3 counts/pixel for M32). Folding line_6: through the SYNPHOT-generated response functions, gives 1.15e-3 line_7: counts/pixel in the F175W filter and 8.71e-3 counts/pixel with F275W line_8: for M31. For M32, the background is 1.13e-3 and 1.30e-2, respectively. line_9: Airglow + detector background: line_10: - For 90 degree solar zenith angle, Fig. 41 of the FOC Instrument line_11: Handbook gives 2.0e-2 counts/pixel with no filters. The resulting line_12: rates using the filter transmissions at Ly-alpha from SYNPHOT are line_13: 2.0e-3 and 5.9e-7 through the F175W and F275W filters, respectively. line_14: Detector background (dark count) was taken to be 6e-4 counts/pixel. line_16: Exposure times were calculated using equation 1 of section 6.0 in the line_17: FOC Instrument Handbook. While profile fitting will be used to do the line_18: photometry in the real data, for our purposes here we computed the line_19: exposure times for stars measured through apertures of the sizes given line_20: in the different rows of Table 9, and chose the aperture with the line_21: shortest exposure time. In the Table below, R_S_tot is the count rate line_22: for a source with an ST magnitude of m_F175W = 21 in the f/48 F175W line_23: filter, integrated over the entire PSF, R_B_tot is the total ! question: 4 section: 5 line_1: background in counts/pixel, and R_S and R_B are the source and line_2: background count rates in a 0.176 arcsec radius aperture. line_4: RESULTS OF EXPOSURE TIME ESTIMATE line_5: Galaxy Filter R_S_tot R_B_tot R_S R_B Exposure (sec) line_6: M31 F175W 0.24 1.9e-3 0.11 0.57 16000 line_7: M31 F275W 0.58 9.3e-3 0.13 0.45 11000 line_8: M32 F175W 0.24 1.9e-3 0.11 0.54 16000 line_9: M32 F275W 0.58 1.4e-2 0.13 0.61 16000 line_11: We were granted 14.62 hours of spacecraft time by the TAC. line_12: We must therefore shorten exposure times, and choose to do line_13: so in the F175W filter, where we can get some S/N back line_14: by combining with the existing f/48 images. We put more line_15: time on M31 because the existing f/48 image is slightly line_16: lower qualitiy than the M32 image due to defocussing in line_17: the detector. The exposure times shown in the exposure line_18: log section reflect these modifications of the exposure line_19: times times shown in the above table. ! question: 5 section: 1 line_1: For both the F175W and the F275W exposures, we wish to use the same line_2: orientation as the previous FOC F150W observations. This is to line_3: avoid losing stars off the corners of the field. The desired orientations line_4: are 97D for M31, and 98D for M32. Our pointing positions are line_5: chosen to be the same as those of the FOC F150W observations line_6: (program ID 2719). Our f/96 22x22" field with thus include all line_7: the stars in the F150W f/48 22x22" field. (The existing f/48 line_8: F175W images were taken in zoom mode, and completely include our line_9: proposed f/96 field.) line_11: Our orientation requirements and pointing positions would change line_12: if we were allowed to use f/48 mode, because we would then like line_13: to align the new images with the existing F175W images, rather line_14: than the existing F150W image. ! question: 6 section: 1 line_1: ! question: 7 section: 1 line_1: Data will be reduced at Berkeley using the same procedures that were line_2: used to analyze the F175W image. Source detection will be carried out line_3: by eye and using DAOFIND. Photometry will be performed on the line_4: un-deconvolved images using DAOPHOT. Standard monte-carlo procedures line_5: will be used to estimate completeness. line_7: Both images will be deconvolved to look for extended emission that line_8: might be indicative of planetary nebulae. line_10: Color-magnitude diagrams and color-color diagrams will be be compared line_11: to models constructed from theoretical evolutionary tracks, using line_12: stellar model atmospheres to predict the far-UV fluxes. line_13: Spectral-synthesis software developed by HF for analysis of the HUT line_14: data has been modified to produce the evolutionary tracks shown on line_15: Figs. 2 and 3 of this proposal. Modifications now underway for further line_16: analysis of the HUT data and analysis of the proposed FOC data include line_17: incorporating a realistic spread in metallicity, providing for line_18: different enrichment of metals relative to helium, allowing different line_19: mass-loss laws on the RGB and AGB, and incorporating improved non-LTE line_20: model atmospheres for stars hotter than T_eff = 35000 K. Improved line_21: evolutionary tracks will be incorporated as they become available. line_23: Software developed independently by JMD is being used to model the ! question: 7 section: 2 line_1: luminosity function in the F175W image. The results from the separate line_2: models will be compared in the near future. line_4: A rough division of resonsibilities is as follows: HF is responsible line_5: for coordinating the overall effort, IK and AS provide expertise on the line_6: FOC and will be responsible for the initial data reduction and line_7: photometry. AFD provides expertise on the HUT data. HF and JMD are line_8: responsible for modeling the resulting color-magnitude diagram, line_9: although all will assist in its interpretation. ! question: 8 section: 1 line_1: ! question: 9 section: 1 line_1: King and Deharveng are on the FOC IDT; Davidsen is on the FOS IDT. line_2: The complete list of observations for these teams can be found in line_3: documents readily available. The direct precursor to this proposal is line_5: FOC-3105 UV IMAGING OF THE CENTERS OF M31 AND M32 line_7: Observations possibly related to this proposal include line_9: SAO-3121, MORPHOLOGY OF FAINT GALAXIES - PART II line_10: GTO-1277, IMAGING OF M31-GROUP GALAXIES line_11: GTO-1278, SPECTROSCOPY OF THE CENTERS OF M31, M32, AND NGC 205 line_12: GTO-1279, STRUCTURE OF GLOBULAR CLUSTERS line_13: GTO-1281, THE FAINT POPULATION IN BAADE'S WINDOW line_14: GTO-3218, (continuation of 1279) line_15: GTO-3219, (continuation of 1277) line_16: GTO-3325, (continuation of 1279, 3218) line_17: AUG-3684, IMAGING OF GLOBULAR CLUSTERS line_18: AUG-3685, IMAGING OF HIGH-REDSHIFT FIELD GALAXIES AND CLUSTERS line_19: AUG-3870, IMAGING IN THE M31 GROUP line_20: GTO-4138, IMAGING OF NGC 4472 line_21: GO-3647 THE STAR-FORMING HISTORY OF ELLIPTICAL GALAXIES ! question: 9 section: 2 line_1: The GO program is a Cycle-2 program of FOS spectroscopy with Ferguson line_2: as PI and Davidsen among the Co-I's. line_4: 3105 revealed PAGB stars in the center of M31 and showed that they line_5: account for only a small part of the UV upturn. M32 (in 1277) went line_6: into Crane et al., below, which found that none of the ellipticals line_7: observed so far have isothermal centers. ! question: 9 section: 3 line_1: ``The Current Ability of HST to Reveal Morphological Structure in line_2: Medium-Redshift Galaxies'', King, I.R., et al. (8 other authors), line_3: Astron. J. 102, 1553, 1991. line_5: ``Preliminary Analysis of an Ultraviolet HST FOC Image of the Center of line_6: M31'', King, I.R., et al. (19 other authors), Ap. J. Letters, 397, line_7: L35, 1992. line_9: ``FOC Observations of Galaxy Cores'', Crane, P.C., et al. (19 other line_10: authors), submitted to A. J. ! question: 10 section: 1 line_1: HF is funded by an SERC rolling grant for observational astronomy, line_2: through September 1993. Destination thereafter is likely STScI. line_3: Computing facilities at Cambridge include four SUN-4 computers line_4: dedicated to HST projects, with a total of 6 Gigabytes of disk storage, line_5: and exabyte cartridge tape systems for off-line storage. Each SUN has line_6: at least 24 Mb of core memory and three have i860 array processors to line_7: speed up image deconvolutions. These machines operate within a larger line_8: network of SUNs that can be used for HST data analysis as well. An line_9: extensive suite of software is installed on the SUNs, including IRAF, line_10: STSDAS, FIGARO, VISTA, and MEMSYS5. These systems are maintained by an line_11: in-house support staff funded by STARLINK. line_13: The data reduction facilities used by members of the FOC GTO team at line_14: Berkeley are available for this project. This includes four line_15: SPARCstation IPC's with 3 gigabytes of disk space dedicated to HST line_16: work. ! !end of general form text general_form_address: lname: FERGUSON fname: HENRY mi: C. category: PI inst: University of Cambridge addr_1: THE OBSERVATORIES, MADINGLEY ROAD city: CAMBRIDGE zip: CB3 0HA country: UNITED KINGDOM phone: (0223) 337548 telex: 817297 ASTRON G ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: NGC224 name_2: M31 name_3: ANDROMEDA GALAXY descr_1: E,301,910,913 pos_1: RA = 00H 42M 44.90S +/-1", pos_2: DEC = +41D 16' 08.0" +/-1" equinox: 2000 pm_or_par: N acqpr_1: EXT comment_1: FLUX 2 IS ST MAG = 21, OUR DESIRED comment_2: LIMIT FOR 10% PHOTOMETRY. FLUX 3 comment_3: CONVERTS THE OBSERVED F175W MEAN comment_4: BACKGROUND OF 3.2E-3 CTS/S/PIX BACK comment_5: TO A FLUX. THE BACKGROUND IN F/96 comment_6: F175W AND F275W ARE ESTIMATED IN comment_7: QUESTION 4 OF THE GENERAL FORM. fluxnum_1: 1 fluxval_1: SURF(V)=15.75 fluxnum_2: 2 fluxval_2: F(1750)=1.45E-17 fluxnum_3: 3 fluxval_3: SURF-CONT-BKG(1750)=1.02E-16 ! targnum: 2 name_1: NGC221 name_2: M32 descr_1: E,303,910 pos_1: RA = 00H 42M 41.71S +/- 1", pos_2: DEC = +40D 51' 54.1" +/- 1" equinox: 2000 comment_1: FLUX 2 IS ST MAG = 21, OUR DESIRED comment_2: LIMIT FOR 10% PHOTOMETRY. FLUX 3 comment_3: CONVERTS THE OBSERVED F175W MEAN comment_4: BACKGROUND OF 2.9E-3 CTS/S/PIX BACK comment_5: TO A FLUX. THE BACKGROUND IN F/96 comment_6: F175W AND F275W ARE ESTIMATED IN comment_7: QUESTION 4 OF THE GENERAL FORM. fluxnum_1: 1 fluxval_1: SURF(V)=15.77 fluxnum_2: 2 fluxval_2: F(1750)=1.45E-17 fluxnum_3: 3 fluxval_3: SURF-CONT-BKG(1750)=9.2E-17 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: NGC224 config: FOC/96 opmode: IMAGE aperture: 512X1024 sp_element: F175W num_exp: 1 time_per_exp: 9199S priority: 3 param_1: PIXEL=50X25 req_1: CYCLE 3; req_2: ORIENT 97D +/- 5D; comment_1: ORIENT REQUIRED TO KEEP SAME STARS AS comment_2: PREVIOUS F150W OBSERVATION. IT IS comment_3: PERMISSIBLE TO INCREASE ORIENT BY comment_4: 90D OR 180D. WOULD LIKE TO HAVE AT comment_5: LEAST THREE SUBEXPOSURES READ OUT comment_6: IF SCHEDULING ALLOWS. ! linenum: 2.000 targname: NGC224 config: FOC/96 opmode: IMAGE aperture: 512X1024 sp_element: F275W num_exp: 1 time_per_exp: 11396S priority: 1 param_1: PIXEL=50X25 req_1: CYCLE 3; req_2: SAME ORIENT FOR 2 AS 1 comment_1: ORIENT REQUIRED TO KEEP SAME STARS AS comment_2: PREVIOUS F150W OBSERVATION. IT IS comment_3: PERMISSIBLE TO INCREASE ORIENT BY comment_4: 90D OR 180D. WOULD LIKE TO HAVE AT comment_5: LEAST THREE SUBEXPOSURES READ OUT comment_6: IF SCHEDULING ALLOWS. ! linenum: 3.000 targname: NGC221 config: FOC/96 opmode: IMAGE aperture: 512X1024 sp_element: F175W num_exp: 1 time_per_exp: 4599S priority: 4 param_1: PIXEL=50X25 req_1: CYCLE 3; req_2: ORIENT 98D +/- 5D; comment_1: ORIENT REQUIRED TO KEEP SAME STARS AS comment_2: PREVIOUS F150W OBSERVATION. IT IS comment_3: PERMISSIBLE TO INCREASE ORIENT BY comment_4: 90D OR 180D. WOULD LIKE TO HAVE AT comment_5: LEAST THREE SUBEXPOSURES READ OUT comment_6: IF SCHEDULING ALLOWS. ! linenum: 4.000 targname: NGC221 config: FOC/96 opmode: IMAGE aperture: 512X1024 sp_element: F275W num_exp: 1 time_per_exp: 16000S priority: 2 param_1: PIXEL=50X25 req_1: CYCLE 3; req_2: SAME ORIENT FOR 4 AS 3 comment_1: ORIENT REQUIRED TO KEEP SAME STARS AS comment_2: PREVIOUS F150W OBSERVATION. IT IS comment_3: PERMISSIBLE TO INCREASE ORIENT BY comment_4: 90D OR 180D. WOULD LIKE TO HAVE AT comment_5: LEAST THREE SUBEXPOSURES READ OUT comment_6: IF SCHEDULING ALLOWS. ! ! end of exposure logsheet ! No scan data records found