- ID:
- ivo://CDS.VizieR/J/A+A/550/A9
- Title:
- VIPGI spectroscopic templates for FORS2
- Short Name:
- J/A+A/550/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The goal of this paper is twofold. Firstly, we present F-VIPGI, a new version of the VIMOS Interactive Pipeline and Graphical Interface (VIPGI) adapted to handle FORS2 spectroscopic data taken with the standard instrument configuration. Secondly, we investigate the spectro-photometric properties of a sample of galaxies residing in distant X-ray selected galaxy clusters, the optical spectra of which were reduced with this new pipeline.
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- ID:
- ivo://CDS.VizieR/J/A+A/615/A96
- Title:
- VI photometry in 3 dwarf galaxies
- Short Name:
- J/A+A/615/A96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundance and spatial distribution of dwarf galaxies are excellent empirical benchmarks against which to test models of structure formation on small scales. The nearby Centaurus group, with its two subgroups centered on Cen A and M 83, stands out as an important alternative to the Local Group for scrutinizing cosmological model predictions in a group of galaxies context. We have obtained deep optical images of three recently discovered M 83 satellite galaxy candidates with the FORS2 instrument mounted on the Very Large Telescope. We aim to confirm their group membership and study their stellar population. Deep V I-band photometry was used to resolve the brightest stars in our targets. Artificial star tests are performed to estimate the completeness and uncertainties of the photometry. The color-magnitude diagrams reveal the red giant branch (RGB) stars, allowing us to use the Sobel edge detection method to measure the magnitude of the RGB tip and thus derive distances and group membership for our targets. The mean metallicity of the dwarf galaxies were further determined by fitting BASTI model isochrones to the mean RGB locus.
- ID:
- ivo://CDS.VizieR/J/AJ/128/224
- Title:
- VI photometry in M33 outer regions
- Short Name:
- J/AJ/128/224
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep CCD photometry in the VI passbands using the WIYN 3.5m telescope of a field located approximately 20 southeast of the center of M33; this field includes the region studied by Mould & Kristian in 1986ApJ...305..591M. The color-magnitude diagram (CMD) extends to I~25 and shows a prominent red giant branch (RGB), along with significant numbers of asymptotic giant branch and young main-sequence stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/424/1113
- Title:
- VI photometry in Phoenix dwarf galaxy
- Short Name:
- J/MNRAS/424/1113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a wide-area photometric survey of the Phoenix dwarf galaxy, one of the rare dwarf irregular/dwarf spheroidal transition-type galaxies (dTs) of the Local Group (LG). These objects offer the opportunity to study the existence of possible evolutionary links between the late- and early-type LG dwarf galaxies, since the properties of dTs suggest that they may be dwarf irregulars in the process of transforming into dwarf spheroidals. Using FORS at the Very Large Telescope (VLT), we have acquired VI photometry of Phoenix. The data reach a signal-to-noise ratio (S/N)~10 just below the horizontal branch of the system and consist of a mosaic of images that covers an area of 26x26arcmin^2^ centred on the coordinates of the optical centre of the galaxy.
- ID:
- ivo://CDS.VizieR/J/AJ/149/66
- Title:
- VI photometry of 8 Cepheid candidates in M31
- Short Name:
- J/AJ/149/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ultra-long-period Cepheids (ULPCs) are classical Cepheids with pulsation periods exceeding ~80days. The intrinsic brightness of ULPCs are ~1 to ~3mag brighter than their shorter period counterparts. This makes them attractive in future distance scale work to derive distances beyond the limit set by the shorter period Cepheids. We have initiated a program to search for ULPCs in M31, using the single-band data taken from the Palomar Transient Factory, and identified eight possible candidates. In this work, we presented the VI-band follow-up observations of these eight candidates. Based on our VI-band light curves of these candidates and their locations in the color-magnitude diagram and the Period-Wesenheit diagram, we verify two candidates as being truly ULPCs. The six other candidates are most likely other kinds of long-period variables. With the two confirmed M31 ULPCs, we tested the applicability of ULPCs in distance scale work by deriving the distance modulus of M31. It was found to be {mu}_M31,ULPC_=24.30+/-0.76mag. The large error in the derived distance modulus, together with the large intrinsic dispersion of the Period-Wesenheit (PW) relation and the small number of ULPCs in a given host galaxy, means that the question of the suitability of ULPCs as standard candles is still open. Further work is needed to enlarge the sample of calibrating ULPCs and reduce the intrinsic dispersion of the PW relation before re-considering ULPCs as suitable distance indicators.
- ID:
- ivo://CDS.VizieR/J/ApJ/654/186
- Title:
- VI photometry of Cepheids in NGC 5128
- Short Name:
- J/ApJ/654/186
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss a new distance to NGC 5128 (Centaurus A) based on Cepheid variables observed with the Hubble Space Telescope. Twelve F555W (V) and six F814W (I) epochs of cosmic-ray-split WFPC2 observations were obtained. A total of 56 bona fide Cepheids were discovered, with periods ranging from 5 to ~50 days; five of these are likely Population II Cepheids of the W Virginis class, associated with the bulge or halo of NGC 5128.
- ID:
- ivo://CDS.VizieR/J/AJ/124/3222
- Title:
- VI photometry of Draco and UMi galaxies
- Short Name:
- J/AJ/124/3222
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present (V, I) photometry of two wide (~25x25arcmin^2^) fields centered on the low surface brightness dwarf spheroidal galaxies Draco and Ursa Minor. New estimates of the distance to these galaxies are provided [(m-M)_0_(UMi)=19.41+/-0.12 and (m-M)_0_(Dra)=19.84+/-0.14], and a comparative study of their evolved stellar population is presented.
- ID:
- ivo://CDS.VizieR/J/A+AS/124/559
- Title:
- VI photometry of dwarf galaxies
- Short Name:
- J/A+AS/124/559
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tables show the photometry and colour index for the observed galaxy, with the image parameter SHARP. This parameter is a measure of the difference between the observed width of the object and the psf model.
- ID:
- ivo://CDS.VizieR/J/MNRAS/343/665
- Title:
- VI photometry of globular cluster systems
- Short Name:
- J/MNRAS/343/665
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have studied the globular cluster systems of seven giant, edge-on spiral galaxies using Hubble Space Telescope imaging in V and I. The galaxy sample covers the Hubble types Sa to Sc, allowing us to study the variation of the properties of globular cluster systems along the Hubble sequence.
- ID:
- ivo://CDS.VizieR/J/ApJ/453/48
- Title:
- VI photometry of HST faint field galaxies
- Short Name:
- J/ApJ/453/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a complete morphologically classified sample of 144 faint field galaxies from the HST Medium Deep Survey with 20.0=<Imag<22.0mag. We compare the global properties of the ellipticals and early- and late-type spirals and find a non-negligible fraction (13/144) of compact blue [(V-I)<1.0mag] systems with r^1/4^ profiles. We give the differential galaxy number counts for ellipticals and early-type spirals independently and find that the data are consistent with no-evolution predictions based on conventional flat Schechter luminosity functions (LFs) and a standard cosmology. Conversely, late-type/irregulars show a steeply rising differential number count with slope ({delta}logN/{delta}m)=0.64+/-0.1. No-evolution models based on the Loveday et al. (1992ApJ...390..338L) and Marzke et al. (1994AJ....108..437M & 1994ApJ...428...43M) local luminosity functions underpredict the late-type/irregular counts by 1.0 and 0.5dex, respectively, at Imag=21.75mag. Examination of the irregulars alone shows that ~50% appear inert and the remainder have multiple cores. If the inert galaxies represent a non-evolving late-type population, then a Loveday-like LF ({alpha}=~-1.0) is ruled out for these types, and an LF with a steep faint end ({alpha}=~-1.5) is suggested. If multiple core structure indicates recent star formation, then the observed excess of faint blue field galaxies is likely a result of et evolutionary processes acting on a steep field LF for late-type/irregulars. The evolutionary mechanism is unclear, but 60% of the multiple-core irregulars show close companions. To reconcile a Marzke-like LF with the faint redshift surveys, this evolution must be preferentially occurring in the brightest late-type galaxies with z>=0.5 at m_I_=21.75mag.
