We present new B-V color-magnitude diagrams for Fornax globular cluster 3 and the surrounding field where our data reach one magnitude below the horizontal branch which is at V_HB_=21.28. After subtracting the field stars from the cluster CMD, we found no evidence for an intrinsic width of the red giant branch because the scatter is only slightly wider than the photometric errors. We determine that there is an intrinsic width to the horizontal branch because the scatter is larger than the photometric errors. After comparing our data with earlier photometry, we find 7 possible variable stars, both within and outside the instability strip, out of a total of 74 horizontal branch stars. We calculate the horizontal branch type of cluster 3 to be of intermediate color, -0.110+/-0.104, which when compared to Fornax cluster 1, having similar metallicity, suggests a second-parameter pair. Five carbon star candidates identified by Jorgensen & Jimenez (1997, Cat. <J/A+A/317/54>) are marked in the field-subtracted color-magnitude diagram. (c) 1997 American Astronomical Society.
The Fornax cluster provides an unparalleled opportunity of investigating the formation and evolution of early-type galaxies in a dense environment in detail. We aim at kinematically characterising photometrically detected globular cluster (GC) candidates in the core of the cluster. We used VLT/VIMOS spectroscopic data from the FVSS survey in the Fornax cluster, covering one square degree around the central massive galaxy NGC 1399. We confirm a total of 777 GCs, almost doubling previously detected GCs, using the same dataset as was used before. Combined with previous literature radial velocity measurements of GCs in Fornax, we compile the most extensive spectroscopic GC sample of 2341 objects in this environment. We found that red GCs are mostly concentrated around major galaxies, while blue GCs are kinematically irregular and are widely spread throughout the core region of the cluster. The velocity dispersion profiles of blue and red GCs show a quite distinct behaviour. Blue GCs exhibit a sharp increase in the velocity dispersion profile from 250 to 400km/s within 5 arcminutes (~29kpc~1r_eff_ of NGC 1399) from the central galaxy. The velocity dispersion profile of red GCs follows a constant value between 200-300km/s until 8 arcminutes (~46kpc~1.6r_eff_, and then rises to 350km/s at 10 arcminutes (~58kpc~2r_eff_). Beyond 10 arcminutes and out to 40 arcminutes (~230kpc~8r_eff_), blue and red GCs show a constant velocity dispersion of 300+/-50km/s, indicating that both GC populations trace the cluster potential. We kinematically confirm and characterise the previously photometrically discovered overdensities of intra-cluster GCs. We found that these substructured intra-cluster regions in Fornax are dominated mostly by blue GCs.
We present a panoramic study of the Fornax dwarf spheroidal galaxy, using data obtained as part of the VLT Survey Telescope (VST) ATLAS Survey. The data presented here - a subset of the full survey - uniformly cover a region of 25deg^2^ centred on the galaxy, in g, r and i bands. This large area coverage reveals two key differences to previous studies of Fornax. First, data extending beyond the nominal tidal radius of the dwarf highlight the presence of a second distinct red giant branch population. This bluer red giant branch appears to be co-eval with the horizontal branch population. Secondly, a shell structure located approximately 1.4{deg} from the centre of Fornax is shown to be a mis-identified background overdensity of galaxies. This last result casts further doubt on the hypothesis that Fornax underwent a gas-rich merger in its relatively recent past.
We present VLT eclipse photometry for the giant planet CoRoT-1b. We observed a transit in the R-band filter and an occultation in a narrow filter centered on 2.09{mu}m. Our analysis of this new photometry and published radial velocities, in combination with stellar-evolutionary modeling, leads to a planetary mass and radius of 1.07^+0.13^_-0.18_M_{Jup}_ and 1.45^+0.07^_-0.13_R_{Jup}, confirming the very low density previously deduced from CoRoT photometry. The large occultation depth that we measure at 2.09{mu}m (0.278^0.043^_-0.066_% ) is consistent with thermal emission and is better reproduced by an atmospheric model with no redistribution of the absorbed stellar flux to the night side of the planet.
We use the very deep and homogeneous I-band selected dataset of the FORS Deep Field (FDF) to trace the evolution of the luminosity function over the redshift range 0.5<z<5.0. We show that the FDF I-band selection down to I_AB_=26.8 misses of the order of 10% of the galaxies that would be detected in a K-band selected survey with magnitude limit K_AB_=26.3 (like FIRES). Photometric redshifts for 5558 galaxies are estimated based on the photometry in 9 filters (U, B, Gunn g, R, I, SDSS z, J, K and a special filter centered at 834nm).
We present low resolution multi-object spectroscopy of an I-band magnitude limited (I_AB_~23-23.5) sample of galaxies located in an area centered on the Hubble Deep Field-South (HDFS). The observations were obtained using the Focal Reducer/low dispersion Spectrograph (FORS) on the ESO Very Large Telescope. Thirty-two primary spectroscopic targets in the HST-WFPC2 HDFS were supplemented with galaxies detected in the Infrared Space Observatory's survey of the HDFS and the ESO Imaging Deep Survey to comprise a sample of 100 galaxies for spectroscopic observations. Based on detections of several emission lines, such as [OII]3727, H{beta} and [OIII]5007, or of other spectroscopic features, we measured accurate redshifts for 50 objects in the central HDFS and flanking fields. The redshift range of the current sample of galaxies is 0.6-1.2, with a median redshift of 1.13 (at I~23.5 not corrected for completeness). The sample is dominated by starburst galaxies with only a small fraction of ellipticals (~10%). For the emission line objects, the extinction corrected [OII]3727 line strengths yield estimates of star formation rates in the range 0.5-30M_{sun}_/yr. We used the present data to derive the [OII]3727 luminosity function up to redshift of 1.2. When combined with [OII]3727 luminosity densities for the local and high redshift Universe, our results confirm the steep rise in the star formation rate (SFR) to z~1.3.
The Foundation Supernova Survey aims to provide a large, high-fidelity, homogeneous, and precisely calibrated low-redshift Type Ia supernova (SN Ia) sample for cosmology. The calibration of the current low-redshift SN sample is the largest component of systematic uncertainties for SN cosmology, and new data are necessary to make progress. We present the motivation, survey design, observation strategy, implementation, and first results for the Foundation Supernova Survey. We are using the Pan-STARRS telescope to obtain photometry for up to 800 SNe Ia at z<~0.1. This strategy has several unique advantages: (1) the Pan-STARRS system is a superbly calibrated telescopic system, (2) Pan-STARRS has observed 3/4 of the sky in grizyP1 making future template observations unnecessary, (3) we have a well-tested data-reduction pipeline, and (4) we have observed ~3000 high-redshift SNe Ia on this system. Here, we present our initial sample of 225 SN Ia grizP1 light curves, of which 180 pass all criteria for inclusion in a cosmological sample. The Foundation Supernova Survey already contains more cosmologically useful SNe Ia than all other published low-redshift SN Ia samples combined. We expect that the systematic uncertainties for the Foundation Supernova Sample will be two to three times smaller than other low-redshift samples. We find that our cosmologically useful sample has an intrinsic scatter of 0.111mag, smaller than other low-redshift samples. We perform detailed simulations showing that simply replacing the current low-redshift SN Ia sample with an equally sized Foundation sample will improve the precision on the dark energy equation-of-state parameter by 35 per cent, and the dark energy figure of merit by 72 per cent.
Be stars undergo outbursts producing a circumstellar disk from the ejected material. The beating of non-radial pulsations has been put forward as a possible mechanism of ejection. We analyze the pulsational behavior of the early B0.5IVe star HD 49330 observed during the first CoRoT long run towards the Galactical anticenter (LRA1). This Be star is located close to the lower edge of the {beta} Cephei instability strip in the HR diagram and showed a 0.03mag outburst during the CoRoT observations. It is thus an ideal case for testing the aforementioned hypothesis.
We present here the results of a Fourier photometric decomposition of a representative sample of ~100 isolated CIG galaxies (Catalog of Isolated Galaxies) in the morphological range Sb-Sc. This study is an integral part of the AMIGA (Analysis of the Interstellar Medium of Isolated Galaxies) project. It complements the photometric analysis presented in our previous paper for the same sample of disc galaxies by allowing a description of the spiral structure morphology. We also estimate dynamical measures like torque strength for bar and spiral, and also the total non-axisymmetric torque by assuming a constant mass-to-light ratio, and explore the interplay between the spiral and bar components of galaxies. Both the length (l_bar_) and the contrast (e.g. A_2b_) of the Fourier bars decrease along the morphological sequence Sb-Sbc-Sc, with bars in earlier types being longer and showing higher contrast. The bars of Sb galaxies are ~ three times longer than the bars in Sc types, consistent with our previous study. We find that the longer bars are not necessarily stronger (as quantified by the torque Q_b_measure), but longer bars show a higher contrast A_2b_, in very good agreement with theoretical predictions. Our data suggest that bar and spiral components are rather independent in the sense that the torque strengths of the two components are not correlated. The total strength Q_g_ is a very reliable tracer of the bar strength measure Q_b_, the two quantities showing a very tight linear correlation. Comparison with a similar sample of disc galaxies (same morphological range) extracted from the OSUBGS (Ohio State University Bright Galaxy Survey) indicates that the isolated CIG/AMIGA galaxies host significantly longer Fourier bars and possibly show a different distribution of spiral torque Q_s_. The Fourier analysis also revealed a potential case of counterwinding spiral structure (KIG652/NGC5768), which deserves further kinematic study. We find that m=2 (i.e. dominating two-armed pattern) is the most common spiral arm multiplicity among the sample of Sb-Sc CIG/AMIGA galaxies (~40 per cent), m=2 and 3 and m=1 and 2 are found in ~28 and ~13 per cent of isolated galaxies, respectively.
The superb phase resolution and quality of the OGLE data on LMC and SMC Cepheids, together with existing data on Galactic Cepheids, are combined to study the period-colour (PC) and amplitude-colour (AC) relations as a function of pulsation phase. Our results confirm earlier work that the LMC PC relation (at mean light) is more consistent with two lines of differing slopes, separated at a period of 10 days. However, our multi-phase PC relations reveal much new structure which can potentially increase our understanding of Cepheid variables. These multi-phase PC relations provide insight into why the Galactic PC relation is linear but the LMC PC relation is non-linear. This is because the LMC PC relation is shallower for short (logP<1) and steeper for long (logP>1) period Cepheids than the corresponding Galactic PC relation. Both of the short and long period Cepheids in all three galaxies exhibit the steepest and shallowest slopes at phases around 0.75-0.85, respectively. A consequence is that the PC relation at phase ~0.8 is highly non-linear. Further, the Galactic and LMC Cepheids with logP>1 display a flat slope in the PC plane at phases close to the maximum light. When the LMC period- luminosity (PL) relation is studied as a function of phase, we confirm that it changes with the PC relation. The LMC PL relation in V- and I-band near the phase of 0.8 provides compelling evidence that this relation is also consistent with two lines of differing slopes joined at a period close to 10 days.
