! 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