The Fornax Cluster Spectroscopic Survey (FCSS) is an all-object survey of a region around the Fornax Cluster of galaxies undertaken using the 2dF multi-object spectrograph on the Anglo-Australian Telescope. Its aim was to obtain spectra for a complete sample of all objects with 16.5 < b_j < 19.7 irrespective of their morphology (i.e. including `stars', `galaxies' and `merged' images). We explore the extent to which (nearby) cluster galaxies are present in 2MASS. We consider the reasons for the omission of 2MASS galaxies from the FCSS and vice versa. We consider the intersection (2.9 square degrees on the sky) of our data set with the infra-red 2 Micron All-Sky Survey (2MASS), using both the 2MASS Extended Source Catalogue (XSC) and the Point Source Catalogue (PSC). We match all the XSC objects to FCSS counterparts by position and also extract a sample of galaxies, selected by their FCSS redshifts, from the PSC. We confirm that all 114 XSC objects in the overlap sample are galaxies, on the basis of their FCSS velocities. A total of 23 Fornax Cluster galaxies appear in the matched data, while, as expected, the remainder of the sample lie at redshifts out to z = 0.2 (the spectra show that 61% are early type galaxies, 18% are intermediate types and 21% are strongly star forming).The PSC sample turns out to contain twice as many galaxies as does the XSC. However, only one of these 225 galaxies is a (dwarf) cluster member. On the other hand, galaxies which are unresolved in the 2MASS data (though almost all are resolved in the optical) amount to 71% of the non-cluster galaxies with 2MASS detections and have redshifts out to z=0.32.
The Fornax Spectroscopic Survey is a large optical spectroscopic survey of ALL 14,000 objects with 16.5<Bj<19.7 in a 12 sq.deg area of sky centered on the Fornax Cluster. We are using the 400-fibre Two Degree Field spectrograph on the Anglo-Australian Telescope: the multiplex advantage of this system allows us to observe objects conventionally classified as `stars' as well as `galaxies'. This is the only way to minimise selection effects caused by image classification or assessing cluster membership. In this paper we present the first measurements of low surface brightness (LSB) galaxies we ha…
Thanks to the 2dF spectrograph on the Anglo-Australian Telescope, we have recently completed the first stage of a complete spectroscopic survey more than one order of magnitude larger than any previous study, measuring 7000 spectra in a 6 sq.deg. area as part of our study of the Fornax Cluster. In this article we describe the public release of 3600 spectra from our first field. We hope that this public release will encourage colleagues making surveys for rare objects to choose these fields, as much of the follow-up spectroscopy that might be required is available from our data.
The Fornax Spectroscopic Survey will use the Two degree Field spectrograph (2dF) of the Anglo-Australian Telescope to obtain spectra for a complete sample of all 14000 objects with 16.5<=Bj<=19.7 in a 12 square degree area centred on the Fornax Cluster. By selecting all objects---both stars and galaxies---independent of morphology, we cover a much larger range of surface brightness and scale size than previous surveys. In this paper we present results from the first 2dF field. Redshift distributions and velocity structures are shown for all observed objects in the direction of Fornax, includin…
We present a study of the internal kinematics and stellar populations of early-type galaxies in the Fornax cluster based on integral-field spectroscopic observations with Gemini South GMOS and VLT-VIMOS. Seven galaxies in a luminosity range of -21.3 < M_B < -17.7 have been observed with these integral field units (IFU). As first results, velocity and line strength maps are presented for NGC 1427 and NGC 1419.
We have used the 2dF spectrograph on the Anglo-Australian Telescope to obtain a complete spectroscopic sample of all objects in the magnitude range, Bj= 16.5 to 19.8, regardless of morphology, in an area centred on the Fornax Cluster of galaxies. Among the unresolved targets are five objects which are members of the Fornax Cluster. They are extremely compact stellar systems with scale lengths less than 40 parsecs. These ultra-compact dwarfs are unlike any known type of stellar system, being more compact and significantly less luminous than other compact dwarf galaxies, yet much brighter than a…
We describe a sample of thirteen bright (18.5<Bj<20.1) compact galaxies at low redshift (0.05<z<0.21) behind the Fornax Cluster. These galaxies are unresolved on UK Schmidt sky survey plates, so would be missing from most galaxy catalogs compiled from this material. The objects were found during initial observations of The Fornax Spectroscopic Survey. This project is using the Two-degree Field spectrograph on the Anglo-Australian Telescope to obtain spectra for a complete sample of all 14000 objects, stellar and non-stellar, with 16.5<Bj<19.7, in a 12 square degree area centered on the Fornax …
We briefly review our photometric and spectroscopic study of RR Lyrae variable stars in the bar of the Large Magellanic Cloud (LMC), that allowed us to reconcile the so-called "short" and "long" distance moduli of the LMC on the value mod_LMC=18.51 +/- 0.085 mag. Then we present preliminary results from the photometric study of a 33' x 34' area in the Fornax dwarf spheroidal galaxy containing the stellar clusters Fornax 3 (NGC 1049) and 6. We identified about 1000 candidate variables in this field of Fornax, and report the first detection and measure of about 60 RR Lyrae variable stars in the …
We present a new set of deep HI observations of member galaxies of the Fornax cluster. We detected 35 cluster galaxies in HI. The resulting sample, the most comprehensive to date, is used to investigate the distribution of HI in the cluster galaxies. We compare the HI content of the detected cluster galaxies with that of field galaxies by measuring HI mass-to-light ratios and the HI deficiency parameter of Solanes et al. (1996). The mean HI mass-to-light ratio of the cluster galaxies is 0.68+/-0.15, significantly lower than for a sample of HI-selected field galaxies (1.15+/-0.10), although not…
This paper investigates the possibility that UCD galaxies in the Fornax cluster are formed by the threshing of nucleated, early-type dwarf galaxies (hereafter dwarf galaxies). Similar to the results of Cote et al. (2006) for the Virgo cluster, we show that the Fornax Cluster observations are consistent with a single population in which all dwarfs are nucleated, with a ratio of nuclear to total magnitude that varies slowly with magnitude. Importantly, the magnitude distribution of the UCD population is similar to that of the dwarf nuclei in the Fornax cluster. The joint population of UCDs and t…
Major axis rotation curves and velocity dispersions profiles, extending out to about one effective radius, are presented for 15 ellipticals and S0's out of the photometric sample of Fornax cluster galaxies studied by Caon \etal\ (1994). A brief description of the spectroscopic and photometric characteristics of each galaxy is provided, together with a comparison with previous studies. Six of the nine E's are possibly misclassified S0's or ellipticals harboring a disk-like component. Two galaxies (NGC~1399 and 1404) show a hint of counter-rotation. Evidence is given that the \bright\ and the \o…
To study the effect of metallicity on the mass-loss of AGB stars, we have conducted mid-infrared photometric measurements of AGB stars in the Sagittarius and Fornax Dwarf Spheroidal Galaxies ([Fe/H]=-1.1 and -1.3) with the 10-micron camera of VISIR at the VLT. These observations combined with previous near-infrared photometric measurements allow us to estimate mass-loss rates in these galaxies. We show here that the observed AGB display dust-driven mass-loss. Dust mass-loss rate are found to be in the range 0.2$\times10^{-10}-1.3\times10^{-8}$ M$_{\odot}$yr$^{-1}$ for the observed AGB stars in…
We present the results of spectroscopic observations of 10 nucleated dwarf elliptical galaxies (dE's) in the Fornax cluster. The blue spectra of Fornax dE galaxies indicate a wide range of metallicities at a given luminosity, similar to those of intermediate to \it metal-rich globular clusters. Metal abundances derived in this paper are well correlated with optical colors and agree with previous spectroscopic results. A discrepancy with metallicities inferred from infrared colors is evident; possible causes include an intermediate age population and dilution of spectral features by a blue ligh…
Various formation channels for the puzzling ultra-compact dwarf galaxies (UCDs) have been proposed in the last few years. To better judge on some of the competing scenarios, we present spectroscopic [Fe/H] estimates for a sample of 26 compact objects in the central region of the Fornax cluster, covering the magnitude range of UCDs and bright globular clusters. We find a break in the metallicity distribution of compact objects at M_V ~ -11 mag (~3*10^6 M_sun): for M_V<-11 mag the mean metallicity is [Fe/H]=-0.62 +/- 0.05 dex, 0.56 +/- 0.15 dex higher than for M_V>-11 mag. This metallicity break…
New measurements of K-band spectral features are presented for eleven early-type galaxies in the nearby Fornax galaxy cluster. Based on these measurements, the following conclusions have been reached: (1) in galaxies with no signatures of a young stellar component, the K-band Na I index is highly correlated with both the optical metallicity indicator [MgFe]' and central velocity dispersion; (2) in the same galaxies, the K-band Fe features saturate in galaxies with sigma > 150 km/s while Na I (and [MgFe]') continues to increase; (3) [Si/Fe] (and possibly [Na/Fe]) is larger in all observed Forna…
We have measured central line strengths for a magnitude-limited sample of early-type galaxies in the Fornax cluster, comprising 11 elliptical (E) and 11 lenticular (S0) galaxies, more luminous than MB=-17. When compared with single-burst stellar population models we find that the centres of Fornax ellipticals follow a locus of fixed age and have metallicities varying roughly from half solar to two times solar. The centres of (lower luminosity) lenticular galaxies, however, exhibit a substantial spread to younger luminosity-weighted ages indicating a more extended star formation history. Galaxi…
The relation between the Ultra Compact Objects (UCOs) recently discovered in the Fornax cluster (Drinkwater et al. 2000, Hilker et al. 1999) and the brightest globular clusters associated with the central galaxy NGC 1399 has been investigated. The question was adressed whether the UCOs constitute a distinct population of objects not linked to globular clusters or whether there is a smooth transition between both populations. Therefore, a spectroscopic survey on compact objects in the central region of the Fornax cluster was carried out with the 2.5m du Pont telescope (LCO). UCOs and the bright…
We model three dSph galaxies, Draco, Ursa Minor and Fornax, as axisymmetric stellar systems embedded in spherical dark-matter potentials, which are in dynamical equilibrium without significant external tidal forces. We construct non-parametric two- and three-integral models that match the observed surface-density profiles and the current kinematic samples of $\sim150-200$ stars per galaxy; these models naturally produce the so-called ``extra-tidal extensions", which had previously been suggested as evidence of tidal stripping. Isochrone, NFW and power-law models fit the data, but we strongly r…
Based on FORS2-VLT long-slit spectroscopy, the analysis of the central absorption line indices of 9 S0 galaxies in the Fornax Cluster is presented. Central indices correlate with central velocity dispersions as observed in ellipticals. However, the stellar population properties of these S0s indicates that the observed trends are produced by relative differences in age and alpha-element abundances and not in metallicity ([Fe/H]) as previous studies have found in elliptical galaxies. The observed scatter in the line indices vs. velocity dispersion relations can be partially explained by the rota…
The Fornax Cluster Spectroscopic Survey (FCSS) project utilises the 2dF multi-object spectrograph on the AAT. Its aim is to obtain spectra for a complete sample of all 14000 objects with 16.5<bj<19.7 irrespective of their morphology in a 12 sq deg area centred on the Fornax Cluster. A sample of 24 Fornax Cluster members has been identified from the first 2dF field (3.1 sq deg in area) to be completed. This is the first complete smaple of cluster objects of known distance with well defined selection limits. 19 of the galaxies (with -15.8<M_B<-12.7) appear to be conventional dwarf elliptical or …
We have measured central line strengths for a complete sample of early type galaxies in the Fornax cluster, comprising 11 elliptical and 11 lenticular galaxies, more luminous than M_B=-17. In contrast to the elliptical galaxies in the sample studied by Gonzalez (and recently revisited by Trager) we find that the Fornax ellipticals follow the locus of galaxies of fixed age in Worthey's models and have metallicities varying from roughly solar to three times solar. The lenticular galaxies however exhibit a substantial spread to younger luminosity weighted ages indicating a more extended star form…
Radial velocities of 94 galaxies brighter than about V_tot = 20 mag in the direction of the central Fornax cluster have been measured. Except for 8 Fornax members, all galaxies lie in the background. Among the 8 members, there are 5 nucleated dwarf ellipticals that are already listed in the FCC (Ferguson 1989, AJ 98, 367). Two of the 3 ``new'' members are very compact and have surface brightnesses comparable to globular clusters, however their luminosities are in the range of dwarf elliptical nuclei. The measured line indices (especially Mg2, H beta, and iron) of the brighter of the compact ob…
We studied the properties of the globular cluster systems of five early--type galaxies in the Fornax galaxy cluster: NGC 1374, NGC 1379, NGC 1387, NGC 1427, and the central giant elliptical NGC 1399. From the investigation of their number of globular clusters, specific frequency, color distribution, surface density profile, and spatial distribution, we conclude that our faint ellipticals have no more globular clusters than spirals of the same mass, and neither differ in their other properties. For these galaxies there is no need to imply a different formation scenario of the globular cluster s…
We present the results of a spectroscopic survey of 675 bright (16.5<Bj<18) galaxies in a 6 degree field centred on the Fornax cluster with the FLAIR-II spectrograph on the UK Schmidt Telescope. We measured redshifts for 516 galaxies of which 108 were members of the Fornax Cluster. Nine of these are new cluster members previously misidentified as background galaxies. The cluster dynamics show that the dwarf galaxies are still falling into the cluster whereas the giants are virialised. Our spectral data reveal a higher rate of star formation among the dwarf galaxies than suggested by morphologi…
The Fornax Cluster is a conspicuous cluster of galaxies in the southern hemisphere and the second largest collection of early-type galaxies within <~ 20 Mpc after the Virgo Cluster. In this paper,we present a brief introduction to the ACS Fornax Cluster Survey - a program to image, in the F475W (g_475) and F850LP (z_850) bandpasses, 43 early-type galaxies in Fornax using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. Combined with a companion survey of Virgo, the ACS Virgo Cluster Survey, this represents the most comprehensive imaging survey to date of early-type galaxies…
We have used a large format CCD camera to survey the nearby Fornax cluster and its immediate environment for low luminosity low surface brightness galaxies. Recent observations indicate that these are the most dark matter dominated galaxies known and so they are likely to be a good tracer of the dark matter in clusters. We have identified large numbers of these galaxies consistent with a steep faint end slope of the luminosity function (alpha~ -2) down to MB ~ -12. These galaxies contribute almost the same amount to the total cluster light as the brighter galaxies and they have a spatial exten…
We have measured K-band surface brightness fluctuations (SBFs) of 19 early-type galaxies in the Fornax cluster. Combining our results with published data, we find the absolute SBF magnitude Mbar_K = (-5.84)+(3.6)*[(V-I)-1.15]. The intrinsic cosmic scatter of Mbar_K appears to be larger than that of I-band SBFs. The discovery of a correlation between K-band SBFs and V-I color is a new clue into the star formation histories of early-type galaxies. This relation naturally accounts for galaxies previously claimed to have anomalously bright K-band SBFs, namely M32 and NGC 4489. Models indicate that…
We present studies of the Extreme Ultraviolet (EUV) emission in the Fornax cluster of galaxies; a relatively nearby well-studied cluster with X-ray emitting cluster gas and a very large radio source. We examine both the large-scale (~size of the X-ray emitting cluster gas), and the small-scale (<arcmin) emission. We find that this cluster has large-scale diffuse EUV emission. However, at the sensitivity level of the existing EUVE data, this emission is due entirely to the low energy tail of the X-ray emitting gas. We have also examined small-scale structures in raw EUVE images of this cluster.…
We report the results of a survey for novae in and between the galaxies of the Fornax cluster. Our survey provides strong evidence that intracluster novae exist and that they provide a useful, independent measure of the intracluster light in Fornax. We discovered six strong nova candidates in six distinct epochs spanning eleven years from 1993 to 2004. The data were taken with the 4m and the 1.5m telescopes at CTIO. The spatial distribution of the nova candidates is consistent with $\sim$16-41% of the total light in the cluster being in the intracluster light, based on the ratio of the number …
We have identified ten candidate intergalactic planetary nebulae in the Fornax galaxy cluster. These objects were found during observations in 1992 and 1993 in three fields chosen well away from any Fornax galaxy at 15 arcmin, 30 arcmin, and 45 arcmin from the centre of Fornax. We used the usual method of blinking images taken in a narrow OIII filter, with images taken in an adjacent broad filter. The measured fluxes in the narrow, broad, and I bands are consistent with these unresolved objects being planetary nebulae immersed in an intergalactic population of stars. Such a population is expec…
We present a photometric study of the globular cluster systems of the Fornax cluster galaxies NGC 1374, NGC 1379, and NGC 1387. The data consists of images from the wide-field MOSAIC Imager of the CTIO 4-m telescope, obtained with Washington C and Kron-Cousins R filters. The images cover a field of 36 x 36 arcmin, corresponding to 200 x 200 kpc at the Fornax distance. Two of the galaxies, NGC 1374 and NGC 1379, are low-luminosity ellipticals while NGC 1387 is a low-luminosity lenticular. Their cluster systems are still embedded in the cluster system of NGC 1399. Therefore the use of a large fi…
We acquired radial velocities of a significant number of globular clusters (GCs) on wide fields between galaxies in the nearby Fornax cluster of galaxies, in order to derive their velocity dispersion radial profile and to probe the dynamics of the cluster. We used FLAMES on the VLT to obtain accurate velocities for 149 GCs, within a ~500x150 kpc strip centered on NGC 1399, the Fornax central galaxy. These objects are at the very bright tail (M_V < -9.5) of the GC luminosity function, overlapping the so-called ``ultra-compact dwarfs'' magnitude range. Eight of the brightest FLAMES-confirmed mem…
By utilising the large multi-plexing advantage of the 2dF spectrograph on the Anglo-Australian Telescope, we have been able to obtain a complete spectroscopic sample of all objects in a predefined magnitude range, 16.5<Bj<19.7, regardless of morphology, in an area towards the centre of the Fornax Cluster of galaxies. Among the unresolved or marginally resolved targets we have found five objects which are actually at the redshift of the Fornax Cluster, i.e. they are extremely compact dwarf galaxies or extremely large star clusters. All five have absorption line spectra. With intrinsic sizes les…
We present BVI photometry of 190 galaxies in the central region of the Fornax Cluster observed with the Michigan Curtis Schmidt Telescope. The cluster members exhibit a strong surface brightness-magnitude relation in our data: both giant and dwarf ellipticals decrease in surface brightness as luminosity decreases. However the surface brightness-magnitude relation is no longer a reliable method for determining cluster membership at surface brightnesses fainter than 22 mag/sq.arcsec. The newly discovered ultra-compact dwarf galaxies (UCDs) lie well off the normal surface brightness-magnitude rel…
We describe a population of compact objects in the centre of the Fornax Cluster which were discovered as part of our 2dF Fornax Spectroscopic Survey. These objects have spectra typical of old stellar systems, but are unresolved on photographic sky survey plates. They have absolute magnitudes -13<Mb<-11, so they are 10 times more luminous than any Galactic globular clusters, but fainter than any known compact dwarf galaxies. These objects are all within 30 arcminutes of the central galaxy of the cluster, NGC 1399, but are distributed over larger radii than the globular cluster system of that ga…
We present the combined results of two investigations: a large-scale study of the globular cluster system (GCS) around NGC 1399, the central galaxy of the Fornax cluster, and a study of the GCSs around NGC 1374, NGC 1379 and NGC 1387, three low-luminosity early-type galaxies located close to the centre of the same cluster. In both cases, the data consist of images from the wide-field MOSAIC Imager of the CTIO 4-m telescope, obtained with Washington C and Kron-Cousins R filters, which provide good metallicity resolution. The colour distributions and radial projected densities of the GCSs are an…
The Multibeam survey at the Parkes Radio Telescope has provided a wealth of 21 cm HI data. We have mosaicked ten standard HIPASS cubes to produce a datacube approximately 25 deg x 25 deg in size, centred on NGC1399, the optical centre of the Fornax Cluster. Some properties of the initial approx. 80 galaxies identified in HI are described. In the optical, Ferguson's Fornax Cluster Catalogue (FCC) identified 340 likely member galaxies in the central 40 sq.deg. In the radio we have detected a more uniform sheet of about 80 galaxies at the cluster velocity extending up to 15 deg from the cluster c…
We present the results of a search for globular clusters in the surroundings of 15 low surface brightness dwarf galaxies belonging to the Fornax Cluster, which was carried out on CCD images obtained with the C and T1 filters of the Washington photometric system. The globular cluster candidates show an extended and probably bimodal (C-T1) color distribution, which is inconsistent with the presence of a single population of metal-poor clusters detected in several dwarf galaxies. The surface number density of these candidates shows no concentration towards the respective dwarf galaxies, in whose …
We describe a search for compact dwarf galaxies in the Fornax cluster using the FLAIR spectrograph on the UK Schmidt Telescope. We measured radial velocities of 453 compact galaxies brighter than Bt=17.3 and found seven new compact dwarf cluster members that were not classified in previous surveys as members of the cluster. These are amongst the most compact, high surface brightness dwarf galaxies known. The inclusion of these galaxies in the cluster does not change the total luminosity function significantly but they are important because of their extreme nature; one in particular appears to …
In this paper we briefly review the properties of the dwarf galaxy population at the core of the Fornax cluster, as well as the properties of the extraordinary rich globular cluster system and the cD halo around the central galaxy NGC 1399. In turn, the question whether a scenario in which dwarf galaxies have been accreted and dissolved in the cluster center can explain the observed properties is addressed. The possibility of accretion of a certain number of dwarf galaxies, the stripping of their globular clusters and gas, and the formation of new globular clusters from stripped infalling gas …
We present the results of a search for clusters in dwarf irregular galaxies in the Virgo and Fornax Cluster using HST WFPC2 snapshot data. The galaxy sample includes 28 galaxies, 11 of which are confirmed members of the Virgo and Fornax clusters. In the 11 confirmed members, we detect 237 cluster candidates and determine their V magnitudes, V-I colors and core radii. After statistical subtraction of background galaxies and foreground stars, most of the cluster candidates have V-I colors of -0.2 and 1.4, V magnitudes lying between 20 and 25th magnitude and core radii between 0 and 6 pc. Using H…
The luminosity gap between novae (M_R < -10) and supernovae (M_R > -14) is well known since the pioneering research of Zwicky and Hubble. Nearby galaxy clusters and concentrations offer an excellent opportunity to search for explosions brighter than classical novae and fainter than supernovae. Here, we present the results of a B-band survey of 23 member galaxies of the Fornax cluster, performed at the Las Campanas 2.5-m Irene duPont telescope. Observations with a cadence of 32 minutes discovered no genuine fast transient to a limiting absolute magnitude of M_B=-9.3 mag. We provide a detailed a…
To study the effect of metallicity on the mass-loss rate of asymptotic giant branch (AGB) stars, we have conducted mid-infrared photometric measurements of such stars in the Sagittarius (Sgr dSph) and Fornax dwarf spheroidal galaxies with the 10-$μ$m camera VISIR at the VLT. We derive mass-loss rates for 29 AGB stars in Sgr dSph and 2 in Fornax. The dust mass-loss rates are estimated from the $K-[9]$ and $K-[11]$ colours. Radiative transfer models are used to check the consistency of the method. Published IRAS and Spitzer data confirm that the same tight correlation between $K-[12]$ colour and…
We present extended stellar kinematics for a sample of 13 elliptical galaxies in the Fornax cluster. Major-axis velocity dispersion profiles (VDPs) and rotation curves (RCs) are given for 12 of the galaxies. A major feature of this data is the spatial extension: for 8 galaxies the data extends beyond 1 R_e, and for 5 it extends beyond 2 R_e. Compared to the previously available data, this corresponds to an increase in spatial coverage by a factor from 1 to 5. Five of the ellipticals in the sample turn out to be rotationally-supported systems, having positive rotation parameter log (V/sigma)*. …
We present HI 21cm line observations, obtained with the Australia Telescope Compact Array, of two dwarf elliptical galaxies (dEs) in the Fornax cluster: FCC032 and FCC336. The optical positions and velocities of these galaxies place them well within the Fornax cluster. FCC032 was detected at the 3sigma significance level with a total HI flux density of 0.66+-0.22 Jy km s^-1 or an HI mass of 5.0+-1.7 10^7 h_75^-2 M_sun. Based on our deep Halpha+[NII] narrow-band images, obtained with FORS2 mounted on the VLT, this dE was already known to contain 600-1800 h_75^-2 M_sun of ionised Hydrogen (depen…
We studied and compared the radial profiles of globular clusters and of the stellar bulge component in three galaxies of the Fornax cluster observed with the WFPC2 of the HST. A careful comparative analysis of these distributions confirms that stars are more concentrated toward the galactic centres than globular clusters, in agreement with what was observed in many other galaxies. If the observed difference is the result of evolution of the globular cluster system sstarting from initial profiles similar to those of the halo--bulge stellar components, a relevant fraction of their mass (74%, 47%…
This article presents and discusses a method for measuring the proper motions of the Galactic dwarf spheroidal galaxies using images taken with the Hubble Space Telescope. The method involves fitting an effective point spread function to the image of a star or quasi-stellar object to determine its centroid with an accuracy of about 0.005 pixel (0.25 milliarcseconds) -- an accuracy sufficient to measure the proper motion of a dwarf spheroidal galaxy using images separated by just a few years. The data consist of images, dithered to reduce the effects of undersampling, taken at multiple epochs w…
We review some properties of ultracompact dwarf galaxies (UCDs) in Fornax and of their brighter counterparts in Abell 1689, among which are two M32 twins, and discuss various possible UCD formation scenarios. We note that it is indispensable to carefully take into account the bright end of the globular cluster luminosity function when estimating the number density of UCDs. It is suggested that the search for more luminous UCDs in dense and rich galaxy clusters is the best way towards establishing UCDs as a new class of galaxies.
We are using the 2dF spectrograph on the Anglo-Australian Telescope to obtain spectra for a complete sample of all 14000 objects with 16.5<B<19.7 in a 12 square degree area centred on the Fornax cluster. The aims of this project include the study of dwarf galaxies in the cluster (both known low surface brightness objects and putative normal surface brightness dwarfs) and a comparison sample of background field galaxies. We will also measure quasars, any previously unrecognised compact galaxies and a large sample of Galactic stars. Here we present initial results from the first 680 objects obse…
We present spectroscopic data for individual stars observed from 2004 March through 2008 August as part of our Michigan/MIKE Fiber System (MMFS) survey of four dwarf spheroidal (dSph) galaxies: Carina, Fornax, Sculptor and Sextans. Using MMFS at the Magellan/Clay Telescope at Las Campanas Observatory, we have acquired 8855 spectra from 7103 red giant candidates in these Galactic satellites. We list measurements of each star's line-of-sight velocity (median error +/- 2.1 km/s) and spectral line indices for iron and magnesium absorption features. We use globular cluster spectra to calibrate the …
The results of the Fornax Compact Object Survey (FCOS) are presented. The FCOS aims at investigating the nature of the Ultra Compact Dwarf galaxies (UCDs) recently discovered in the center of the Fornax cluster (Drinkwater et al. 2000). 280 unresolved objects in the magnitude space covering UCDs and bright globular clusters (18<V<21 mag) were observed spectroscopically. 54 new Fornax members were discovered, plus five of the seven already known UCDs. Their distribution in radial velocity, colour, magnitude and space was investigated. It is found that bright compact objects (V<20 or M_V<-11.4 m…
We have obtained long-slit spectroscopy for a sample of 9 S0 galaxies in the Fornax Cluster using the FORS2 spectrograph at the 8.2m ESO VLT. From these data, we have extracted the kinematic parameters, comprising the mean velocity, velocity dispersion and higher-moment H3 and H4 coefficients, as a function of position along the major axes of these galaxies. Comparison with published kinematics indicates that earlier data are often limited by their lower signal-to-noise ratio and relatively poor spectral resolution. The greater depth and higher dispersion of the new data mean that we reach wel…
We have discovered about 70 very faint dwarf galaxies in the Fornax Cluster. These dSphs candidates follow the same magnitude-surface brightness relation as their counterparts in the Local Group, and even extend it to fainter limits. The faintest dSph candidate in our sample has an absolute magnitude of M_V = -8.8 mag and a central surface brightness of mu_V = 27 mag/arcsec^2. There exists a tight color-magnitude relation for the early-type galaxies in Fornax that extends from the giant to the dwarf regime. The faint-end slope of the luminosity function of the early-type dwarfs is flat (alpha …
We present a photometric catalog (based on V and I photometry) of galaxies in the central regions of the Fornax galaxy cluster. Our 11 CCD fields cover 0.17 degrees in total. The limiting surface brightness is around 24 mag arsec^-2, similar to that of Ferguson's (1989, AJ 98, 367) catalog, whereas our limiting total magnitude is around V = 22 mag, about two magnitudes fainter. It is the surface brightness limit, however, that prevents us from detecting the counterparts of the faintest Local Group dwarf spheroidals. The photometric properties of all objects are presented as a catalog. The prop…
We are using the Multibeam 21cm receiver on the Parkes Telescope combined with the optical Two degree Field spectrograph (2dF) of the Anglo-Australian Telescope to obtain the first complete spectroscopic sample of the Fornax cluster. In the optical the survey is unique in that all objects (both ``stars'' and ``galaxies'') within our magnitude limits (Bj=16.5 to 19.7) are measured, producing the most complete survey of cluster members irrespective of surface brightness. We have detected two new classes of high surface brightness dwarf galaxy in the cluster. With 2dF we have discovered a populat…
We present the first dynamical analysis of a galaxy cluster to include a large fraction of dwarf galaxies. Our sample of 108 Fornax Cluster members measured with the UK Schmidt Telescope FLAIR-II spectrograph contains 55 dwarf galaxies (15.5>bj>18.0 or -16>Mb>-13.5). Halpha emission shows that 36+/-8 per cent of the dwarfs are star-forming, twice the fraction implied by morphological classifications. The total sample has a mean velocity of 1493+/-36 km/s and a velocity dispersion of 374+/-26 km/s. The dwarf galaxies form a distinct population: their velocity dispersion (429+/-41 km/s) is large…
We investigate, via numerical simulations, the tidal stripping and accretion of globular clusters (GCs). In particular, we focus on creating models that simulate the situation for the GC systems of NGC 1404 and NGC 1399 in the Fornax cluster, which have poor (specific frequency $S_{\rm N}$ $\sim$ 2) and rich ($S_{\rm N}$ $\sim$ 10) GC systems respectively. We initially assign NGC 1404 in our simulation a typical $S_{\rm N}$ ($\sim$ 5) for cluster ellipticals, and find that its GC system can only be reduced through stripping to the presently observed value, if its orbit is highly eccentric (wit…
Aims. We determine masses and mass-to-light ratios of five ultra-compact dwarf galaxies and one dwarf elliptical nucleus in the Fornax cluster from high resolution spectroscopy. Methods. Velocity dispersions were derived from selected wavelength regions using a direct-fitting method. To estimate the masses of the UCDs a new modelling program has been developed that allows a choice of different representations of the surface brightness profile (i.e. Nuker, Sersic or King laws) and corrects the observed velocity dispersions for observational parameters (i.e. seeing, slit size). Results. The obse…
We investigate whether the globular clusters (GCs) in the recently published sample of GCs in the Fornax cluster by Bergond and coworkers are indeed intra-cluster objects. We combine the catalogue of radial velocity measurements by Bergond et al. with our CTIO MOSAIC photometry in the Washington system and analyse the relation of metal-poor and metal-rich GCs with their host galaxies. The metal-rich GCs appear to be kinematically associated with their respective host galaxies. The vast majority of the metal-poor GCs found in between the galaxies of the Fornax cluster have velocities which are …
We derive the relative distances to the Virgo, Fornax, and Coma clusters of galaxies by applying the Dn-sigma and the Fundamental Plane (FP) relations to the data of the homogeneous samples of early--type galaxies studied by Caon etal, Lucey etal, and Jorgensen etal. The two distance indicators give consistent results, the relative distance moduli to Fornax and Coma with respect to Virgo being Dmu(FV)=0.45+-0.15 and Dmu(CV)=3.55+-0.15) respectively. The formal error on D(m-M) may be as small as 0.07 mag (~3% in distance), provided that all the sources of bias are taken into account and a corre…
Type Ia supernovae are the best cosmological standard candles available. The intrinsic scatter of their decline-rate- and colour-corrected peak brightnesses in the Hubble diagram is within observational error limits, corresponding to an uncertainty of only 3km/s/Mpc of the Hubble constant. Any additional uncertainty, resulting from peak-brightness calibration, must be kept small by measuring distances to nearby host galaxies most precisely. A number of different distance determinations of the Fornax cluster of galaxies agree well on a distance modulus of 31.35+-0.04mag (18.6+-0.3Mpc). This lea…
