181 research outputs found
Observations of field and cluster RR Lyræ with Spitzer. Towards high precision distances with Population II stellar tracers
Indexación: Scopus.We present our project to calibrate the RR Lyræ period-luminosity-metallicity
relation using a sample of Galactic calibrators in the halo and globular clusters.https://www.epj-conferences.org/articles/epjconf/pdf/2017/21/epjconf_puls2017_07004.pd
Dark halo structure in the Carina dwarf spheroidal galaxy: joint analysis of multiple stellar components
Photometric and spectroscopic observations of the Carina dSph revealed that
this galaxy contains two dominant stellar populations of different age and
kinematics. The co-existence of multiple populations provides new constraints
on the dark halo structure of the galaxy, because different populations should
be in equilibrium in the same dark matter potential well. We develop
non-spherical dynamical models including such multiple stellar components and
attempt to constrain the properties of the non-spherical dark halo of Carina.
We find that Carina probably has a larger and denser dark halo than found in
previous works and a less cuspy inner dark matter density profile, even though
the uncertainties of dark halo parameters are still large due to small volume
of data sample. Using our fitting results, we evaluate astrophysical factors
for dark matter annihilation and decay and find that Carina should be one of
the most promising detectable targets among classical dSph galaxies. We also
calculate stellar velocity anisotropy profiles for both stellar populations and
find that they are both radially anisotropic in the inner regions, while in the
outer regions the older population becomes more tangentially biased than the
intermediate one. This is consistent with the anisotropy predicted from tidal
effects on the dynamical structure of a satellite galaxy and thereby can be
considered as kinematic evidence for the tidal evolution of Carina.Comment: 14 pages, 7 figures and 3 tables. Accepted for publication in MNRA
RR Lyrae mid-infrared Period-Luminosity-Metallicity and Period-Wesenheit-Metallicity relations based on Gaia DR3 parallaxes
We present new empirical infrared Period-Luminosity-Metallicity (PLZ) and
Period-Wesenheit-Metallicity (PWZ) relations for RR Lyrae based on the latest
Gaia EDR3 parallaxes. The relations are provided in the WISE and
bands, as well as in the and Wesenheit
magnitudes. The relations are calibrated using a very large sample of Galactic
halo field RR Lyrae stars with homogeneous spectroscopic [Fe/H] abundances
(over 1,000 stars in the band), covering a broad range of metallicities
(). We test the performance of our
PLZ and PWZ relations by determining the distance moduli of both galactic and
extragalactic stellar associations: the Sculptor dwarf spheroidal galaxy in the
Local Group (finding ), the Galactic globular
clusters M4 () and the Reticulum globular cluster
in the Large Magellanic Cloud (). The distance
moduli determined through all our relations are internally self-consistent
(within 0.05 mag) but are systematically smaller (by
2-3) than previous literature measurements taken from a variety of
methods/anchors. However, a comparison with similar recent RR Lyrae empirical
relations anchored with EDR3 likewise shows to varying extents a systematically
smaller distance modulus for PLZ/PWZ RR Lyrae relations.Comment: Accepted by ApJ, 14 pages, 5 Figures, 2 Table
Fiducial Stellar Population Sequences for the VJKs Photometric System
We have obtained broad-band near-infrared photometry for seven Galactic star
clusters (M92, M15, M13, M5, NGC1851, M71 and NGC6791) using the WIRCam
wide-field imager on the Canada-France-Hawaii Telescope, supplemented by images
of NGC1851 taken with HAWK-I on the VLT. In addition, 2MASS observations of the
[Fe/H] ~ 0.0 open cluster M67 were added to the cluster database. From the
resultant (V-J)-V and (V-Ks)-V colour-magnitude diagrams (CMDs), fiducial
sequences spanning the range in metallicity, -2.4 < [Fe/H] < +0.3, have been
defined which extend (for most clusters) from the tip of the red-giant branch
(RGB) to ~ 2.5 magnitudes below the main-sequence turnoff. These fiducials
provide a valuable set of empirical isochrones for the interpretation of
stellar population data in the 2MASS system. We also compare our newly derived
CMDs to Victoria isochrones that have been transformed to the observed plane
using recent empirical and theoretical colour-Teff relations. The models are
able to reproduce the entire CMDs of clusters more metal rich than [Fe/H] ~
-1.4 quite well, on the assumption of the same reddenings and distance moduli
that yield good fits of the same isochrones to Johnson-Cousins BV(RI)C
photometry. However, the predicted giant branches become systematically redder
than the observed RGBs as the cluster metallicity decreases. Possible
explanations for these discrepancies are discussed.Comment: 18 pages, 20 figures, Accepted for publication in A
Establishment and characterization of induced pluripotent stem cell (iPSCs) line UNIBSi014-A from a healthy female donor.
Abstract Peripheral blood mononuclear cells (PBMCs) derived from a healthy 40-year-old female were successfully transformed into induced pluripotent stem cells (iPSCs) by using the integration-free CytoTune-iPS Sendai Reprogramming method. The resulting iPSCs line exhibits a normal karyotype, expresses stemness markers and displays the differentiation capacity into the three germ layers. This human iPSCs line can be used as healthy control in disease modelling studies
New theoretical period-luminosity-metallicity relations for RR Lyrae in the Rubin-LSST filters
Metallicity of Galactic RR Lyrae from optical and infrared light curves. II. Period-Fourier-metallicity relations for first overtone RR Lyrae
- …