! File: 4240C.PROP ! Database: PEPDB ! Date: 20-FEB-1994:18:43:09 coverpage: title_1: PAGB STARS IN ELLIPTICAL AND BULGE-DOMINATED title_2: NEARBY GALAXIES -- REPEAT FOR HOPR#61 sci_cat: STELLAR POPULATIONS sci_subcat: OLD FIELD STARS proposal_for: RPT/GO cont_id: 2719 pi_title: PROF. pi_fname: FRANCESCO pi_lname: BERTOLA pi_inst: DEPARTMENT OF ASTRONOMY PADUA UNIVERSITY pi_country: ITALY pi_phone: +39-49-661499 keywords_1: PAGB STARS, POPULATION II, ELLIPTICAL GALAXIES, keywords_2: UV IMAGING hours_pri: 7.05 num_pri: 3 foc: Y funds_amount: 32816 funds_length: 12 funds_date: OCT-91 pi_position: PROF. OF ASTRONOMY off_fname: CESARE off_lname: CHIOSI off_title: PROFESSOR off_inst: DIPARTIMENTO DI ASTRONOMIA off_addr_1: VICOLO OSSERVATORIO,5 off_city: PADOVA off_zip: I-35122 off_country: ITALY off_phone: +39-49-661499 off_telex: 432071 ASTROS I ! end of coverpage abstract: line_1: We propose to search for the stellar population which produces the far line_2: ultraviolet rising branch from 1200-1800 A in the spectral energy line_3: distributions of early-type galaxies. One of the most likely sources of this line_4: hot emission are evolved post-asymptotic giant branch (PAGB) stars. We estimate line_5: that the brightest PAGB stars at the distance of M31 can be unambiguously line_6: detected using the far-UV imaging capabilities of HST+FOC. The possible line_7: presence of other kinds of hot stellar components that could contribute flux to line_8: the rising branch (e.g. young stars, accreting white dwarf stars in binaries) line_9: can also be detected in these images, as they will be intrinsically brighter line_10: than PAGB stars, but less numerous. If the source of this far -UV flux is PAGB line_11: stars, their absolute magnitudes in galaxies of different mean metallicities line_12: are critical tests of current theories of PAGB evolution. ! ! end of abstract general_form_proposers: lname: BERTOLA fname: FRANCESCO title: PROF. inst: DEPARTMENT OF ASTRONOMY PADUA UNIVERSITY country: ITALY esa: Y ! lname: BURSTEIN fname: DAVID title: DR. inst: ARIZONA STATE UNIVERSITY country: USA ! lname: BUSON fname: LUCIO title: DR. mi: M. inst: ASTRONOMICAL OBSERVATORY PADUA country: ITALY esa: Y ! lname: CHIOSI fname: CESARE title: PROF. inst: DEPARTMENT OF ASTRONOMY PADUA UNIVERSITY country: ITALY esa: Y ! lname: DI SEREGO ALIGHIERI fname: SPERELLO title: DR. inst: ARCETRI ASTROPHYSICAL OBSERVATORY country: ITALY esa: Y ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: We propose to image the central regions of M31, M32 and NGC 205 by using the line_2: FOC in the F/48 configuration. We need to image each target using the far-UV line_3: filter F150W. To avoid problems related to the disuniformity in the response line_4: and defect in the photocatode, we are requesting that two images (about one line_5: hour each) be obtained for each galaxy, in order to provide reliable number line_6: counts of faint UV-bright stars (a critical test of the new PAGB models). line_7: The F150W filter isolates the spectral region where PAGB stars are relatively line_8: the brightest, and where the galaxy background is very low. The bulge of M31 line_9: is an object of high metallicity for which we expect about 200 bright PAGB line_10: stars within the F/48 aperture. Fewer bright PAGB stars are expected in M32 line_11: (about 20), both from the known lower UV flux in that galaxy, and from the line_12: lower metallicity. The fewest PAGB stars are expected to be found in NGC 205, line_13: but blue horizontal branch stars could be present if there is a wide mix of line_14: metallicity in this galaxy. In addition, the presence of known, ongoing star line_15: formation in NGC 205 could contribute significant numbers of main sequence, line_16: stars even in regions without obvious star formation. In all cases we expect line_17: to detect individual stars in these galaxies, of which both the luminosities line_18: and the number will be important to this study. ! question: 4 section: 1 line_1: To detect bright PAGB stars (Mv about +1) in external galaxies it is line_2: necessary to operate in the far-UV (both where they emit their largest flux, line_3: and at which they are more easily discriminated against redder stars) with a line_4: large telescope, since they are faint (mv > 25). High angular resolution is line_5: necessary to isolate crowded objects against a non negligible background. line_6: The observations here proposed represent a one of the final goals of a long line_7: term project carried out by the proposers both from space (IUE) and from the line_8: ground (Lick Observatory), as well through theoretical modelling of the late line_9: stages of stellar evolution. ! question: 5 section: 1 line_1: Our estimate of the exposure times with the aberrated HST is based on the line_2: following ingredients: 1. We require a 10% photometric accuracy (S/N=10) for line_3: a PAGB star at the knee of the slowest of the Schoenberner (1983, Ap.J. 272, line_4: 708) evolutionary tracks (M_core=0.546M_o, log L/L_o=2.95, log T_e=4.93, line_5: hereafter our reference PAGB star) and a clear detection (S/N=5) for a PAGB line_6: star which is one magnitude fainter. 2. We concentrate on the F/48 + F150W line_7: combination, which gives the best contrast between the hot stellar population line_8: and the underlying cold stars. 3. We use the measured FOC PSF in the UV and line_9: in particular the fact that 15% of the PSF flux is contained in the central line_10: 13 pixels (radius of 0.09 arcsec). This core is the important part of the PSF line_11: for the detection and measurement of faint point sources. 4. We consider the line_12: following components of the background: the detector background as measured line_13: in orbit (0.0019 cnt/s/pix), the sky background, which is dominated by the line_14: diffuse galactic light as given in Fig. 42 of the FOC Instrument Handbook, line_15: and the contribution due to unresolved sources and to the wings of the PSF line_16: of the resolved sources. In order to estimate this third background component line_17: we take all the flux measured by Burstein et al. (1988, Ap.J. 328, 440) in line_18: the large IUE aperture and we assume it is distributed with a radial profile line_19: like the B-band one given by Kent (1987, A.J. 94, 306) for M32. In a 2 hour line_20: exposure with the F150W filter, subdivided into two single exposures slightly line_21: shifted by 1 arcsec, we foresee a S/N varying between 8 at the nucleus and 14 line_22: at the edge of the field for our reference PAGB star, while S/N will be 5 at 2 line_23: arcsec from the nucleus and 7 at the edge for a PAGB one magnitude fainter. ! question: 7 section: 1 line_1: We plan to use the data from the pipeline calibration (RSDP) at STScI. line_2: Eventual recalibration is possible at the ST-ECF using IRAF/STDAS and line_3: the instrument database (CDBS). Analysis of the data will be carried out line_4: with the photometric packages in MIDAS (ROMAFOT, DAOPHOT), available line_5: at ESO, Firenze and Padova. ! question: 10 section: 1 line_1: VAX 730+1.5Gb disk+Jupiter 7 Image Disp/Decnetted to VAX 780 cluster at line_2: Dept. of Astronomy ASU. VAX 8530 + MIDAS/IRAF reduction packages in Padova. line_3: SUN IPC Workstations + MIDAS/IRAF packages in Firenze. ! !end of general form text general_form_address: lname: BERTOLA fname: FRANCESCO title: PROF. category: PI addr_1: DIP.TO DI ASTRONOMIA addr_2: VICOLO OSSERVATORIO, 5 city: PADOVA I-35122 country: ITALY ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: NGC221-UV-STARS name_2: M32 descr_1: EXT-STAR; PAGB STAR; HOST=NGC221 pos_1: PLATE-ID = 01JV, pos_2: RA = 0H 42M 41.71S +/- 0.05S, pos_3: DEC = +40D 51' 54.1" +/- 0.5" equinox: 2000 rv_or_z: V = -217 comment_1: FLUXVAL_2 IS FOR THE REFERENCE comment_2: PAGB STAR AT 4" FROM THE NUCLEUS. fluxnum_1: 1 fluxval_1: V=18.7+/-0.5, TYPE=O5 V, E(B-V)=0.08 fluxnum_2: 2 fluxval_2: F(1500)=11+/-4E-18 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: NGC221-UV-STARS config: FOC/48 opmode: IMAGE aperture: 512X512 sp_element: F150W num_exp: 1 time_per_exp: 24M s_to_n: 10 fluxnum_1: 2 priority: 1 req_1: GUIDE TOL 0.010"; req_2: CYCLE 1 ! ! end of exposure logsheet ! No scan data records found