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The Distance to NGC 5128 (Centaurus A)
No full textAbstractIn this paper we review the various high precision methods that are now available to determine the distance to NGC 5128. These methods include: Cepheids, TRGB (tip of the red giant branch), PNLF (planetary nebula luminosity function), SBF (surface brightness fluctuations), and Long Period Variable (LPV) Mira stars. From an evaluation of these methods and their uncertainties, we derive a best-estimate distance of 3.8±0.1 Mpc to NGC 5128 and find that this mean is now well supported by the current data. We also discuss the role of NGC 5128 more generally for the extragalactic distance scale as a testbed for the most direct possible comparison among these key methods.</jats:p
Long Period Variables in NGC 5128
No full textLong Period Variable stars are ubiquitous among the bright red
giant branch stars in NGC 5128. Mostly they are found
to be brighter than the tip of the first ascent giant branch with magnitudes
ranging from about to . They have periods
between 155 and 1000 days and K-band amplitudes between 0.1 and 2 mag,
characteristic of semi-regular and Mira variables. We
compare the colors, periods and amplitudes of these variables with those
found in old stellar populations like Galactic globular clusters and
Galactic bulge as well as with intermediate-age Magellanic Cloud long period
variables.
The population of stars above the tip of the red giant branch (RGB)
amounts to 2176 stars
in the outer halo field (Field 1) and 6072 stars in the inner halo
field (Field 2). The comparison of the luminosity functions
of the Galactic bulge, M 31 bulge and NGC 5128 halo fields shows an
excess of bright AGB stars extending to .
The large majority of these sources belong to the
asymptotic giant branch (AGB)
population in NGC 5128. Subtracting the foreground
Galactic stars and probable blends, at least 26% and 70%
of AGB stars are variable in Fields 1 and 2, respectively.
The average period of NGC 5128 LPVs
is 395 days and the average amplitude 0.77 mag. Many more short period
Miras are present in Field 2 than in Field 1 indicating a difference in the
stellar populations between the two fields.
Period and amplitude distributions and
near-IR colors of the majority of LPVs in NGC 5128
are similar to the Galactic bulge variables. However, some ~10%
of LPVs have periods longer than 500 days and thus probably more massive,
hence younger, progenitor stars. A few carbon star candidates are
identified based on their red and colors.
The Globular Cluster System of NGC 5128
No full textWe present preliminary results from a new wide-field photometric investigation of the globular cluster system of NGC 5128. NGC 5128 is the nearest giant elliptical and thus its globular cluster system serves as prototype for those of this important galaxy type. We have obtained images from IMACS at the Magellan telescope in excellent seeing that allow us to not only resolve globular clusters but derive their structural parameters. This extensive database provides a wealth of data to study the globular clusters in unprecedented detail. We discuss here the resolution of the clusters and their preliminary structural parameters.Peer reviewed: YesNRC publication: Ye
The distance to the giant elliptical galaxy NGC 5128
No full textThe distance to NGC 5128, the central galaxy of
the Centaurus group and the nearest giant elliptical to us,
has been determined
using two independent distance indicators: the
Mira period-luminosity (PL) relation and the luminosity of the tip
of the red giant branch (RGB). The data were taken at two
different locations in the halo of
NGC 5128 with the ISAAC near-IR array on ESO VLT.
From more than 20 hours of observations with ISAAC a very deep
Ks-band luminosity function was constructed. The tip
of the RGB is detected at mag.
Using an empirical calibration
of the K-band RGB tip magnitude, and
assuming a mean metallicity of dex and
reddening of , a distance modulus of NGC 5128
of was derived. The comparison of
the H-band RGB tip magnitude in NGC 5128 and the Galactic Bulge
implies a distance modulus of NGC 5128 of
in
good agreement with the K-band RGB tip
measurement.
The inner halo field has larger photometric errors, brighter
completeness limits and a larger number of blends.
Thus the RGB tip feature is not as sharp as in the outer halo field.
The population of stars above the tip of the RGB amounts to 2176 stars
in the outer halo field (Field 1) and 6072 stars in the inner halo
field (Field 2). The large majority of these sources belong to the
asymptotic giant branch (AGB)
population in NGC 5128 with numerous long period variables.
Mira variables were used to
determine the distance of NGC 5128 from a period-luminosity relation
calibrated using the Hipparcos parallaxes and LMC Mira period-luminosity
relation in the K-band. This is the first Mira period-luminosity relation
outside the Local Group. A distance modulus
of was derived,
adopting the LMC distance modulus of .
The mean of the two methods yields a
distance modulus to NGC 5128 of
corresponding to Mpc
Block Card 5128 Rowland Road
No full textThis image was produced by the Auditor's Office in Lucas County, Ohio for tax assessment purposes. Associated dates are approximate. Descriptive terms related to this photograph include: Dwelling | 5128 Rowland Road (Toledo, Ohio) | Side gabled | Hopeland (Toledo, Ohio) | Greenwood Area (Toledo, Ohio) | West Toledo Area (Toledo, Ohio) | Folk House Styl
Block Card 5128 Kellogg Road
No full textThis image was produced by the Auditor's Office in Lucas County, Ohio for tax assessment purposes. Associated dates are approximate. Descriptive terms related to this photograph include: Ranch houses | 5128 Kellogg Road (Toledo, Ohio) | Dwelling | Westhaven First Addition (Toledo, Ohio) | Reynolds Corners Area (Toledo, Ohio
The P2X7R-antagonist AFC-5128 ameliorates chronic experimental autoimmune encephalomyelitis in a preventive and therapeutic paradigm
No full textBACKGROUND: Multiple sclerosis (MS) is characterized by chronic inflammation driven by central nervous system (CNS)-resident immune cells such as microglia, especially during the progressive phase of the disease. The P2X7 receptor (P2X7R), a risk protein for MS, is ubiquitously expressed on immune cells. AFC-5128, a CNS-penetrating small molecule inhibitor of P2X7R, is a promising agent for the treatment of autoimmune diseases such as MS.METHODS: In vitro, the effects on the calcium influx of primary murine microglia were assessed via Fluo-4 calcium imaging. In vivo, MOG35-55 immunized C57BL/6 mice were treated with AFC-5128, fingolimod (FTY) or vehicle in different treatment paradigms. The mice were scored daily. Microglial marker expression, immune cell phenotyping and serum cytokine analyses were performed via flow cytometry. Immune cell infiltration, demyelination and Iba1+/CD3+ cells were detected in spinal cord cross-sections. The effects of MOG35-55 T-cell restimulation were assessed in vitro.RESULTS: In vitro, treatment of primary microglia with 10 µM AFC-5128 reduced the influx of calcium following ATP stimulation (p<0.0001). In vivo, treatment of mice with AFC-5128 led to a reduction in overall EAE scores in acute and chronic EAE, with the best effects using 200 mg/kg body weight AFC-5128 (p<0.0001). Peripheral immune cell subsets (B cells, T cells and macrophages) and serum cytokine levels of chronic EAE mice treated in a therapeutic paradigm were not affected. While the expression of homeostasis markers of microglia in AFC-5128-treated mice was not affected, there was a trend toward lower expression of phagocytosis-associated markers. Late therapeutic treatment with AFC-5128 had only mild effects on chronic EAE.CONCLUSION: The treatment of EAE mice with AFC-5128 improved acute and chronic EAE in different treatment paradigms, with positive effects on histological markers and slight modulation of microglial marker expression. Mechanistically, calcium influx of microglia was reduced following AFC-5128 treatment, which implies the ability of AFC-5128 to stabilize calcium homeostasis. Therefore, therapeutic inhibition of P2X7R via AFC-5128 has the potential for translation into a treatment of both relapsing and progressive forms of multiple sclerosis
Spectrophotometry of globular clusters in NGC 5128 (centaurus a) : determination of their metallicities
Get PDFWe have carried out spectrophotometry in the range 3600–9700Å of five globular clusters in NGC 5128 for which previous photometric studies suggested a high metal content. We compare the equivalent widths of a set of metallic features of the NGC 5128 clusters with those of well-studied Galactic and M31 globular clusters. This enables us to derive a reliable ranking and estimate of the metallicity for the NGC 5128 clusters. The reddening is obtained from the comparison of the continuum distribution of the observed clusters with those of reference clusters. The present spectroscopic study clarifies the question raised in the photometric studies about the NGC 5128 clusters metallicities. We conclude that, in the present NGC 5128 sample, no object has actually a metallicity higher than solar, unlike what happens in M31
The P2X7R-antagonist AFC-5128 ameliorates chronic experimental autoimmune encephalomyelitis in a preventive and therapeutic paradigm
No full text Multiple sclerosis (MS) is characterized by chronic inflammation driven by central nervous system (CNS)-resident immune cells such as microglia, especially during the progressive phase of the disease. The P2X7 receptor (P2X7R), a risk protein for MS, is ubiquitously expressed on immune cells. AFC-5128, a CNS-penetrating small molecule inhibitor of P2X7R, is a promising agent for the treatment of autoimmune diseases such as MS.
, the effects on the calcium influx of primary murine microgl\)ia were assessed via Fluo-4 calcium imaging. , MOG immunized C57BL/6 mice were treated with AFC-5128, fingolimod (FTY) or vehicle in different treatment paradigms. The mice were scored daily. Microglial marker expression, immune cell phenotyping and serum cytokine analyses were performed via flow cytometry. Immune cell infiltration, demyelination and Iba1/CD3 cells were detected in spinal cord cross-sections. The effects of MOG T-cell restimulation were assessed .
, treatment of primary microglia with 10 M AFC-5128 reduced the influx of calcium following ATP stimulation (p<0.0001). , treatment of mice with AFC-5128 led to a reduction in overall EAE scores in acute and chronic EAE, with the best effects using 200 mg/kg body weight AFC-5128 (p<0.0001). Peripheral immune cell subsets (B cells, T cells and macrophages) and serum cytokine levels of chronic EAE mice treated in a therapeutic paradigm were not affected. While the expression of homeostasis markers of microglia in AFC-5128-treated mice was not affected, there was a trend toward lower expression of phagocytosis-associated markers. Late therapeutic treatment with AFC-5128 had only mild effects on chronic EAE.
The treatment of EAE mice with AFC-5128 improved acute and chronic EAE in different treatment paradigms, with positive effects on histological markers and slight modulation of microglial marker expression. Mechanistically, calcium influx of microglia was reduced following AFC-5128 treatment, which implies the ability of AFC-5128 to stabilize calcium homeostasis. Therefore, therapeutic inhibition of P2X7R via AFC-5128 has the potential for translation into a treatment of both relapsing and progressive forms of multiple sclerosis
Interstellar lines in the spectra of the globular clusters around NGC 5128
Get PDFThree of the brightest globular clusters associated with the peculiar radio galaxy NGC 5128 have been observed spectroscopically. In addition to interstellar Ca II lines from our own Galaxy, two of the three show interstellar Ca II lines arising in NGC 5128. The radial velocities are not consistent with gas which shares the motion of the elliptical galaxy. In one case, the gas is possibly associated with the rotating inclined disk of gas seen close to the nucleus. The interstellar clouds are between 12 and 30 kpc from the nucleus of NGC 5128, depending on whether they are in an extension of the rotating disk and how the disk is warped
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