1997AJ....113.1001H THEASTRONOMITCALJOURNAL to under however, 4 [email protected], reviews). these retically older carl@ 'Tiepartment [email protected] 5 galactic 6 3 guson 7 2 krist@ [email protected], the way 8 [email protected] 1 11 1001 1 Jet Jet Department Dominion Department Department Based ~ount Space California Dwarf the Propulsion evolution © Propulsion for lb6.jpl.nasa.gov, NASA stsci.edu objects Astron. stars Telescope on & Stromlo low American us systems Astronomical observations extended concentrated distribution defined galaxy, galaxy, and Deep has within tendency based Space small 147 1 Astrophysical Binggeli The Institute elliptical G. detailed of to of contract are of Gyr of luminosities Laboratory, Atmospheric a observationally J. M. E. have understand of have Astronomy, Physics and mean [email protected] Laboratory, study J. Science V on Astronomy, only population 113 Telescope. the BALLESTER, these ago. and while red in HAN, of and KRIST/ Siding both 5-26555. krs of asymptotic 1994, been with been Technology, (3), the context STELLAR stellar galaxies possible value of giant it of Observatory, @lb6.jpl.nasa.gov increasing I and Institute, Astronomical 1. The 2 systems 4800 than shows the Society. the CCD March the universe. and stellar the Spring INTRODUCTION J. New obtained extensively the Gallagher 4800 and J. Astronomy, [email protected] University G. branch NASAIESA of HB absence Oceanic of The distribution population Oak HB of R. the 6 star by images are for 3700 Mexico -0.91 Observatories, HOESSEL,2 a giant EAGB MS 1997 C. small populations theoretical and and Oak MOULD, Grove POPULATIONS clear [S0004-6256(97)02003-7] stars, color-magnitude 5071 metallicity many majority formation the among Over BURROWS, 170-25, Sciences, San with (RGB), the the of branch Grove & in Arizona of West State sizes in Drive, Hubble radial investigated, nearby which Martin stars the RGB investigators Wyse the universe the the studies 10 a Wisconsin of Pasadena, Received J. the Saanich Society central Private University, main University P. models of a Drive, Mail central past provides of variation Wide the history Space (EAGB) with S. indicates Drive, red State 7 appear tip galaxies, SCOWEN, most 1994 older J. these GALLAGHER Stop brightness. sequence decade extending EAGB horizontal at Bag, Road, CLARKE, galactocentric 0004-6256/97 Telescope, 1996 and California Mail diagram IN University, Baltimore, Field VOLUME field, for at large. both of and for numerous 169-237, to Box stars. (see a 2611 systems, stars. THE in • Michigan, Madison, an August the Victoria, the 9 unique be prima- Stop recent hence or the and Provided and theo stars K. ABSTRACT 30001 outer Fer Due Weston 6 more stars evolution presence 91125. obtained so, shows DWARF A A Maryland branch D. The to Pasadena, sense that STAPELFELDT, Tyler III, 7; 179-225, -1.0 Planetary 113, mean BC /113(3)11 similar indicates 2455 revised CR1SP, field Department Madison, 2 with populous radius. metallicity Electronic Creek J. V8X4M6, NUMBER Mall, have a instruments, instrument lagher in tions tions, the rily nificantly Telescope a at in Hayward, (HB), HOLTZMAN, 21218. distance number number of of the California of M ELLIPTICAL Pasadena, the 1996 this 8 dwarf by P.O., age in a 001/10/$10.00 the R. v< Camera-2 intermediate-aged Space dwarf A Tempe, previously of larger Wisconsin which that outer the et mail: 4500, a at December series Electronic metallicity GRIFFITHS, 5 the 1 Canada. A.C.T., Local gradient the [Fe/H] Ann strong al. A. 3 larger shows deeper of elliptical of Local Telescope modulus (HST) 91109. definition the elliptical [email protected] dispersion field; California Arizona LG the WATSON, 1996). LG NASA Las Arbor, is interesting 3 is Group Australia. P. Electronic younger (WFPC2) part red as 10 53706. radii. mail: superb Group that galaxies Electronic Cruces, galaxies. the been level. GALAXY allows B. and is 7 Michigan determined dispersion Science galaxy of clump, 85287. C. of also STETSON, galaxies. Large star [email protected], team 91109. dwarf the These 3 (m- Astrophysics carefully is In Electronic Electronic a GR1LLMA1R, (LG). imaging (several AND New mail: features, us stars seen formation continued mail: outer in Institute, this implied on The Electronic 48109. NGC to and M) to Magellanic elliptical NGC much results Electronic [email protected] Mexico J. board is study While paper, at [email protected] 4 from re-examine are 0 other © field WESTPHAL" © a mail: also J. =24.39 quality studied smaller Electronic Gyr) 147 mail: which including small 1997 TRAUGER, by 147 1997 more more 5 the are ceased the of program 88003-8001. mail: shows most [email protected] present galaxy we J. based [email protected], galaxy mail: 1 the stars Am. is the [email protected], RGB HESTER, considered stellar number of Cloud is prevent American radii. using operated Data detail [email protected], mail: centrally of the derived relative Hubble the at a Astron. on a [email protected], in we in 5 the NGC weak color by least well [email protected], stellar The populations Hubble HST MARCH the the ground-based Electronic (LMC) and 9 have of by System LG our the Soc. AURA, to observa study galaxies WFPC2 popula studied Space a (Gal 1997 1001 mail: sig Inc. of in 1997AJ....113.1001H FIG. u2ob0101t u2obQ103t has u2ob0202p NGC an other content. shown. other and indicators concentrated cently companions of Rootname most u2ob010dt u2ob0102t no u2ob0204p u2ob010bt u2ob0109t u2ob0106t u2ob0105t u2ob0104t u2ob0201p u2ob0108t u2ob0107t u2ob0203p & u2ob010ct u2ob010at (Richer 1002 the Hunter ~ NGC outer stars - 1. ' © long .... : STSci Ill ' ' ~ NGC .. of hand, two ~· A 185 ... - reported ;f '~. HAN . American ... ~'. the 15X et .:. •: younger .. For ... . 147 field ...... ~ . been ... . ~ in companions 1981), Digitized al. and . . 15 companion the 205 ET to example, blue NGC is 1984; arcmin of F555W F814W F814W F555W F555W F814W F814W F814W F555W F555W F555W F555W F814W F555W F814W F555W F814W NGC recognized the ..... one study Filter AL.: the NGC than but all stars Sky TABLE discovery 147 of giant square Davidge NGC ). .. no 205 contain Astronomical Survey. of .. 12 :• early the (Hodge ~. (NGC ~ dwarfs 147 (Hodge • evidence deep 1. :r Gyr. field 147 contain spiral three to Exposure Observation .. by The studies .... 2400 2800 2800 1300 1300 1300 1300 1300 : 1300 1300 1300 1300 1300 ' of 1992; 400 400 500 600 185, of be • ground-based intermediate-age However, to 1963; Mould . .. WFPC2 1976)...... NGC a well ' M31. our special was few dust . ·. NGC Lee have ~· •: Hodge 147, own known log. found et ..... moderately FOVs Moreover, As clouds •: et ' ; Davidge al. Society outer outer outer outer outer inner inner inner inner Field outer outer outer outer outer outer outer outer 205), taken ... in ..... revealed ~ Galaxy, . compared al...... : .. of 1973; terms CCD (1983) , ~ .. ~ ~"· dwarf for . from .. our 1993); and as .. ·: : populations these .. two (1994) ...... well NGC images Gallagher .. the .... bright NGC of that centrally elliptical 24MAY95 24MAY95 24MAY95 24MAY95 detected 21JUN95 21JUN95 21JUN95 21JUN95 21JUN95 21JUN95 21JUN95 21JUN95 21JUN95 21JUN95 21JUN95 21JUN95 21JUN95 • ·• .. . fields ..... archives on Date to stellar Pop ·. .. Provided as both 147 185 the the as- re are in to I fields "See edented obtained cesses dratically in least lowing globular defining in images #1, ID ID DAOPHOT-IIIALLFRAME WF these region, ymptotic known tively. bias populations presents Stetson "The scribed servations. south 6, of 3 3 ology and indicating obtained 2 2 *Tables (b) (a) 1 1997. 1 we two the the Two We Stellar pixels by footnote and coordinate data and of Only in two of conclude of F555W central No 2(a) the have all the fields 798.57 798.63 800.83 800.97 800.78 800.99 Hodge reveal and the the the based fields detail. . in the x• x• the the dark at giant with cluster, PSF the reduction. central 2. varying 4 pointings. TABLE obvious the that TABLE and Figures to photometry Stetson nuclear the procedure in chips OBSERVATIONS on observation obtained first galaxy NASA of other Table system ein centered region the were frames 2(b) images construction the images the on clusters branch In an joining -88 with 1995 2(a). NGC page 2(b). in 1021.15 1022.03 853.44 850.89 Sec. 889.63 978.08 Hodge stellar galaxy WFPC2 can intermediate-age 2(a). Point WFPC2 dark each y• y• 2 in region. selected is (1994b, center. We is NGC Deep degree a NGC and deep June be point obtained stars defined of 147 2 Astrophysics shown in an of summary are apparent are software field clouds below, log. found Spread population was the present in 147-inner 3 a #3, Holtzman 147-Quter outer to with F555W(V) F555W images in 21 on 25.270 for (Plates 25.780 26.247 26.965 26.033 25.998 (see given AND Sees. Figure here CCD be for The by central 1994c). Vo Vo the in which carried for at at 1995 or close WFPC2 we HSTIWFPC2 simply the the Functions our for (Stetson DATA ein centered region of (800,800). the central images our 3, star temperature. field the 31 describe field of and AAS form 1 field HST. our population of in 4, and study May et globular to 0.630 0.724 0.168 0.339 0.148 0.104 is shows Since analyses stacking and NGC and clusters outer uv uv this and REDUCTION either photometry.* al. F814W out photometry. simultaneously, and study. CD-ROM the image some region outer were Data These 1994a), X 24 32) F814W(/) of 5. galaxy (PSF) Handbook (1995) content. and our dates ALLFRAME 2419 region. the with field. Finally, up NGC for 24.861 24.206 24.482 25.224 24.717 25.203 cluster calibrated show fields, other 4 of Y data is The of images observations Io Io high the locations System Series, are derived arcrninutes the using at present, of in the NGC and using the contiguous 147, in method v3.0), than mosaics was Table our unprec another respec images quality central in Hodge units stellar Vol. Pal were 0.125 0.316 0.450 0.166 0.552 0.390 qua 1002 14 Sec. new pro it fol one ob de the 0'[ 0'[ the and by of 7, at is of 8, 4 1 1997AJ....113.1001H in trated FIG. The for able The extinction overplotted Tuc. F555W Holtzman 20, magnitude there time rections were by by photometric single exposures our field, instrument_news/WFPC2/Wfpc2_cte/ctetop.htrnl). geometric 1003 Holtzman's this tion weight-averaged posures, (- field V communication) the The and 50, The P. each Stetson 4. 1000 © images phenomenon output to total problem, by were (400-500 inner further is B. and The 100,200,300,500, photometry HAN reject American I final reliability the moderate 25 20 and 25 20 as for image. we Stetson, are s) magnitudes V field. number distortion et 38,203 (- described number 0 for independently from for were by photometric the vs anomaly magnitudes F814W the ET also al. processed cosmic-ray 200 which each (V-!) The approximately the s) RGB These AL.: effect (1995) using ALLFRAME to density corrected is taken background of may in and s) file in magnitudes of DAOPHOT give the star 0 curves effects NGC our text. magnitudes appears fainter the 700) with Astronomical and using stellar files of for outer his be contours, 0 by and so-called at in were zero-points ALLFRAME events The a ! outer charge stars 0 147 DoPHOT each of found checked the the final correcting each were for vs (Holtzman than the is field the relative Galactic and to objects per (V-!) PSF-fitting converted in WFPC2, cooler 0.05 a this field. which detector make and aperture colors optimal filter. list then photometric transfer the 1/80X80 for observed at long data distribution 0 effect mag http://www.stsci.edu/ftp/ by globular other photometry stellar of were fields, diagrams all are These is a CCD combined for were (1300-2800 versus et photometry star originally 2 Saha drawn 78,421 the that of to estimate (more Society efficiency. corrections al. exposure random magnitudes. based for corrected the in photometry clusters, standard observed we temperature, stars raw for lists of 1995), long window at short coefficients both (1996, made the levels details the in to on and magnitudes all and discovered of hot stars Ml5 exposures produce 78,421 for the our files, exposure time short s). and then and Another area. Cousins • the of the calibra in derived no private Galactic pixels. filters. is and Since Since about pack- (5, Provided inner inner short illus cor raw Also raw stars and one and ex 10, of 47 a A(V for each four overplotted extinction Tuc. in (V- AAS tinction trated FIG. the the within brated ors and age, are order distributions in 20, Also magnitude were stars sity 200, (RGB) the Finally, Our 50, The the E(B- 5. in by inner first listed > outer 0 was 1) columns. by the per )=0.576 table 300, outer 0 CDROM defined overplotted The 100,200,300,600, to the magnitudes 0 CMD, 0.02 V the loci complete the 20 25 20 25 as law to column better 0 grid-area two constructed and are V -(V- fields field. V)(Burstein following in described number 600, 0 are we indicate diagram 3. mag. of vs the NASA by are the to THE outer sets the applied (V-1) The shown and as illustrate the RGB 900) are Cardelli be overlaid of density second /) photometry two COLOR-MAGNITUDE number for in in and magnitudes of Galactic A(/ 0 extinction-corrected fields, (5, each shown 0 curves sections. text. into and 900) stars by the andl the ASCII photometry below. Astrophysics a 3.1 & magnitude 0 10, contours, 0 )=0.365, correction the The and dividing / et table. Heiles on stars inner 0 figures 80X80 0 of respectively. Field density per 20, in -(V- vs al. globular relative relative Galactic and the tables, third A per (V-1) data Figs. 50, grid-area which (1989). field, The colors running Stars diagrams. 1984), 1/80X80 errors are the grids; agree adopting /) contour distribution will for 100, 0 columns, 4 globular Tables coordinates distribution diagrams are 0 and cluster and were DIAGRAMS window diagrams the Galactic We The 2 Rv=3.2, drawn be magnitudes 200, of are Data with number for the (5, 5, corrected the red The clusters, 2(a) published maps use first a given for of 10, respectively, the M15 while window 300, at contour value each the of giant levels the extinction number and for System V 20, of 3 of outer is and of •. 0 stars Ml5 h color the in 500, 38,203 for entries ([Fe/H}= ·...... , : , the the the 2(b), the given and other 50, area. 1-1 the 1 of of the branch Galactic 0 on an is levels and (5, , inner field. stars 700) stars cali den 1003 0.18 100, illus col Also stars and star last ex the for 10, of of In 47 in to 1997AJ....113.1001H rate from fields, in detected dicts lactic total MIS Fla. matter Armandroff role. rate ner below for clearly outer appears dicts each in in affect inner ing CMDs: detected cluster globular RGB stars (Figs. 1004 147 11% -2.17) the the the Some Several (5) (4) (3) (2) (1) 6. that field, the © ([Fe/H]= is in cluster (see number some are in about 19 are field. is The field star inner our outer inner The 4 A No Both Both the somewhat which of the stars clusters HAN present American and outer the the larger much to and plotted above well-defined centered Sec. color-magnitude fact, and of count main analysis HB are extended interesting 22. EAGB 15 was within, The field. main 100 47 -2.17) outer field field, fields fields (1990). ET 5) (V-I)o the of is shown. field (V-/) in foreground 4 broader the This as in level. Tuc I in the are AL.: sequence 405 less below) foreground crowding a model NGC filled and This higher outliers the sequence both respectively, but field, and at actual tiny region show show same about in 2 ([Fe/H]= foreground corresponds Stars and AGB NGC A exposed the 0 inner dots. outer 147, 47 no Astronomical (red) features =0.95, result particular, fields, than diagrams fraction of distance which was Tuc([Fe/H]= in a a magnitude (V-1) HB contalnination 136 Hodge the within of The Hodge stars stars 0 .,'.,-· in 147 Ratnatunga stars in well-defined strong ~ field the horizontal turnoff field 0 0 that stars : used , 5, 5, is about EAGB stars -0.71), the stars ROB and the / by (V-I)o are 2 is of 0 mainly ... in EAGB are 2 stars above 0 of 1, =24.12 to I in than respectively; modulus 0 =0.90, the and inner arcseconds not more with lnight the clump the color-magnitude to immediately loci Hodge are with a level 0 reliably 4% the -0.71} the lilnit. stars predicted scale stars 6 in 2 enough visual taken fraction in of branch clearly the & due arcseconds region. V total in outer field our than RGB; / in Galactic in the in is 2, be / < 0 on Bahcall Society are 0 The in <20.3 the of tip the the the to and at of 27 =24.05 the detected, from Galaxy. smaller magnitude outer the may number overplotted. this field. 1 0 24.39 least regions the of the (HB) to distinguishable inner of the in EAGB We cluster Hodge the contamination contamination outer globular mag evident (V-1) of RGB. the significantly EAGB center fact DaCosta each paper. and (1985) also model I field. the inner-field detected ~ in is of 0 for diagrams field RGB The than than 3. 1.5 • field. of indicat that V center present region, RGBs. the the clusters, 2 play of of These All 0 in range NGC Provided As stars stars > mag pre pre three Ga each and our the the are the the in the 19 & of a a a EAGB the regions ters. [Fe/H]=-1.9±0.15 sults enon 3, of cautionary open of clusters older galaxies color difference in concentration The galaxy increased The outer M Hodge Hodge FIG. three model were weight-averaging within predolninantly (1988) (e.g., =-2.17) 15 Fig. the It contain Three these 7. figure. by RGB field. CMDs The are is is selected circles at .0 z and Distribution clusters, Fall than ;j 8 ... Q) field 2 1, apparent has showed region 1 prediction, 6. consistent the is are 20 40 60 (e.g., in [Fe/H] arcseconds The and stars Hodge 0 phenomenon of crowding. and loci probably is more Note note: & good more the previously quite stars of are that mean NASA the 3 24.5 within than Strom Rees with in 47 of in concentrated respectively. = these field that clusters of that the that stellar metal NGC 3.2 general 2, the shown -2.17 the blue 4 the different HB Tuc the with V a other and 0 judging 2.5u known less stars of 1985). the Globular and et the clusters, radii level the magnitude stars Galactic CMD, clusters 14 field, Astrophysics RGB ([Fe/H]=-0.71) poor been the photometry al. the that Hodge 7 in rejection. metallicities overall agreement in is reliable stars. RGB -2.5±0.25, is in of Outer 1981; from (at central NGC idea Figs. the VHB=25.09:!:0.02, The globular the the and than which reported toward from , 5, 5, The stars, especially for are globular Cluster the 3, locus left that CMD outer globular that Cohen spectroscopic some also than 4 lie 147 Field the filled presented and region same for and and the with show curve within the the defined of of clusters 700 by respectively. for the field region in morphologies 6 Stars the clusters HB 5. 1988.) morphology these globular Hodge the dots arcseconds the are the centers Data the radii) DaCosta clusters stars of a spatial a stars The in which Stars stars our number CMDs each two stronger also Galactic in field 25.5 by of near represent each blue in This most field in Ml5 study in Fig. 1 each the is System of in clusters distribution clusters overlaid cluster, the and NGC have due the estimated their These & as panel. the phenom a stars from majority of of HB 6. of striking ([Fe/H] cluster. of central cluster cluster galaxy Hodge shown mould of to view. these bluer other Stars clus in stars 1004 147, host the the are are are the the the re the in by A 1997AJ....113.1001H inner RGB FIG. / relation the metal-poor tallicity the the will which use red sible CMDs. absolute clump" and galaxy of low Therefore 1005 require some stars scope of level Lyrae by (1991) adopt +17.0(V-I) with "RGB" +0.82. 0 =20.3 the A the In To weight-averaging 8. distance giant clump this low © evaluate the metallicity field using of O<(V-I) was clear tip 4.1 advance facts The RGB of determine the can RGB in HAN stars (to spend American The a iteratively varying indicates relation, In in derived metallicity, I in RGB this both (top) Distance branch / found 0 full properties calculate z 0 theoretical be ..0 ..0 z s s ;j ;j ...... ground-based during Q) Q) detection which our are a magnitude luminosity particular, as ET of Galactic given extinction-corrected 0 fields. paper. 300 (V-I) 200 100 estimated 100 galaxy roughly and ,- 4. 50 of stellar a necessarily deep 0 tip NGC AL.: 0 0 3 to ages, <0.5 1.5 DISTANCE distance part color -4.9[(V-I)o,- 19 we by this the that can their in be and (TRGB) by M NGC o. M photometry which outer like intermediate function of with also a Da Astronomical _ of 147 population luminosity-metallicity 25.09±0.02 1 discussion metallicities equal complicate stars and globular 0 3 range at .) self-consistent Metallicity Lee the using first both their data. as Below from NGC 147 model. Costa absolute field need more a approximate; AND 20 24.5