scholarly journals Multicolor Photometry and Age Estimates of Globular Clusters in M31

2005 ◽  
Vol 13 ◽  
pp. 206-206
Author(s):  
Jun Ma
Keyword(s):  
Globular Clusters ◽  
Band System ◽  
Broad Band ◽  
Spectral Energy ◽  
Population Synthesis ◽  
Intermediate Band ◽  
Wide Range ◽  
The Relationship ◽  
Multicolor Photometry ◽  
Age Estimates

AbstractWe present CCD multicolor photometry for 172 globular clusters (GCs), taken from the Bologna catalog (Battistini et al. 1987), in the nearby spiral galaxy M31. The observations were performed by using the National Astronomical Observatories 60/90 cm Schmidt Telescope in 13 intermediate-band filters, which covered a range of wavelength from 3800 to 10000 Å. This provides a multicolor map of M31 in pixels of 1.7 × 1.7 arcminutes. By aperture photometry, we obtain the spectral energy distributions (SEDs) for these GCs. Using the relationship between the Beijing-Arizona-Taiwan-Connecticut (BATC) intermediate-band system used for the observations and the UBVRI broad-band system, the magnitudes in the B and V bands are derived. The computed V and B–V are in agreement with the values given by Battistini et al. (1987) and Barmby et al. (2000). Finally, by comparing the photometry of each GC with theoretical stellar population synthesis models of Bruzual & Chariot (1996, hereafter BC96), we estimate ages of the sample GCs for different metallicities. The BC96 models provide the evolution in time of the spectrophotometric properties of simple stellar populations for a wide range of stellar metallicity. The results show that nearly all our sample GCs have ages more than 109 years, and most of them are around 1010 years old. At the same time, we find that GCs fitted by the metal-poor model are generally older than ones fitted by the metal-rich model.

scholarly journals Globular clusters in the outer halo of M 31

2019 ◽  
Vol 623 ◽  
pp. A65 ◽  
Author(s):  
Song Wang ◽  
Jun Ma ◽  
Jifeng Liu
Keyword(s):  
Globular Clusters ◽  
Selection Effect ◽  
Population Synthesis ◽  
Clear Trend ◽  
Intermediate Band ◽  
Near Ultraviolet ◽  
Poor Group ◽  
History Of ◽  
M 31 ◽  
Far Ultraviolet

In this paper, we present photometry of 53 globular clusters (GCs) in the M 31 outer halo, including the GALEX far-ultraviolet (FUV) and near-ultraviolet (NUV), SDSS ugriz, 15 intermediate-band filters of BATC, and 2MASS JHKs bands. By comparing the multicolour photometry with stellar population synthesis models, we determine the metallicities, ages, and masses for these GCs, aiming to probe the merging/accretion history of M 31. We find no clear trend of metallicity and mass with the de-projected radius. The halo GCs younger than ∼8 Gyr are mostly located at the de-projected radii around 100 kpc, but this may be due to a selection effect. We also find that the halo GCs have consistent metallicities with their spatially associated substructures, which provides further evidence of the physical association between them. Both the disc and halo GCs in M 31 show a bimodal luminosity distribution. However, we should emphasise that there are more faint halo GCs which are not seen in the disc. The bimodal luminosity function of the halo GCs may reflect a different origin or evolution environment in their original hosts. The M 31 halo GCs include one intermediate metallicity group (−1.5 < [Fe/H] < −0.4) and one metal-poor group ([Fe/H] < −1.5), while the disc GCs have one metal-rich group more. There are considerable differences between the halo GCs in M 31 and the Milky Way (MW). The total number of GCs in M 31 is approximately three times greater than in the MW, however M 31 has about six times more halo GCs than the MW. Compared to the halo GCs of M 31, those of the MW are mostly metal-poor. Both the numerous halo GCs and the higher-metallicity component are suggestive of an active merger history of M 31.

scholarly journals The Relationship between Stellar and Halo Masses of Disk Galaxies at z = 0.2 − 1.2

2004 ◽  
Vol 220 ◽  
pp. 399-404
Author(s):  
Christopher J. Conselice ◽  
Kevin Bundy ◽  
Richard S. Ellis ◽  
Jarle Brinchmann ◽  
Nicole Vogt
Keyword(s):  
Stellar Population ◽  
Hubble Space Telescope ◽  
Spectral Energy ◽  
Disk Galaxies ◽  
Population Synthesis ◽  
Energy Distributions ◽  
Stellar Population Synthesis ◽  
Halo Masses ◽  
Stellar Masses ◽  
The Relationship

We present the results of a study to determine the co-evolution of the virial and stellar masses for a sample of 83 disk galaxies between redshifts z = 0.2 − 1.2. the virial masses of these disks are computed using measured maximum rotational velocities from Keck spectroscopy and scale lengths from Hubble Space Telescope imaging. We compute stellar masses based on stellar population synthesis model fits to spectral energy distributions including K(2.2μm) band magnitudes. We find no apparent evolution with redshift from z = 0.2 − 1.2 in the relationship between stellar masses and maximum rotational velocities through the stellar mass Tully-Fisher relationship. We also find no evolution when comparing disk stellar and virial masses. Massive disk galaxies therefore appear to be already in place, in terms of their virial and stellar masses, out to the highest redshifts where they can be morphologically identified.

scholarly journals Population synthesis of black hole binary mergers from star clusters

2020 ◽  
Vol 492 (2) ◽  
pp. 2936-2954 ◽  
Author(s):  
Fabio Antonini ◽  
Mark Gieles
Keyword(s):  
Black Hole ◽  
Globular Clusters ◽  
Initial Conditions ◽  
Star Clusters ◽  
Population Synthesis ◽  
Wide Range ◽  
Binary Mergers ◽  
Cluster Properties ◽  
Black Hole Binary ◽  
Merger Rate

ABSTRACT Black hole (BH) binary mergers formed through dynamical interactions in dense star clusters are believed to be one of the main sources of gravitational waves (GWs) for Advanced LIGO and Virgo. Here, we present a fast numerical method for simulating the evolution of star clusters with BHs, including a model for the dynamical formation and merger of BH binaries. Our method is based on Hénon’s principle of balanced evolution, according to which the flow of energy within a cluster must be balanced by the energy production inside its core. Because the heat production in the core is powered by the BHs, one can then link the evolution of the cluster to the evolution of its BH population. This allows us to construct evolutionary tracks of the cluster properties including its BH population and its effect on the cluster and, at the same time, determine the merger rate of BH binaries as well as their eccentricity distributions. The model is publicly available and includes the effects of a BH mass spectrum, mass-loss due to stellar evolution, the ejection of BHs due to natal and dynamical kicks, and relativistic corrections during binary–single encounters. We validate our method using direct N-body simulations, and find it to be in excellent agreement with results from recent Monte Carlo models of globular clusters. This establishes our new method as a robust tool for the study of BH dynamics in star clusters and the modelling of GW sources produced in these systems. Finally, we compute the rate and eccentricity distributions of merging BH binaries for a wide range of cluster initial conditions, spanning more than two orders of magnitude in mass and radius.

scholarly journals SPECTRAL ENERGY DISTRIBUTIONS AND AGE ESTIMATES OF 104 M31 GLOBULAR CLUSTERS

2010 ◽  
Vol 139 (4) ◽  
pp. 1438-1450 ◽  
Author(s):  
Song Wang ◽  
Zhou Fan ◽  
Jun Ma ◽  
Richard de Grijs ◽  
Xu Zhou
Keyword(s):  
Globular Clusters ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Age Estimates

scholarly journals J-PLUS: A wide-field multi-band study of the M 15 globular cluster

2019 ◽  
Vol 622 ◽  
pp. A179 ◽  
Author(s):  
Charles Bonatto ◽  
Ana L. Chies-Santos ◽  
Paula R. T. Coelho ◽  
Jesús Varela ◽  
Søren S. Larsen ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Broad Band ◽  
Asymptotic Giant Branch ◽  
Spectral Energy ◽  
Wide Field ◽  
Stellar Photometry ◽  
Spatial Coverage ◽  
Metal Abundances ◽  
Red Giant ◽  
Multi Band

Context. As a consequence of internal and external dynamical processes, Galactic globular clusters (GCs) have properties that vary radially. Wide-field observations covering the entire projected area of GCs out to their tidal radii (rtidal) can therefore give crucial information on these important relics of the Milky Way formation era. Aims. The Javalambre Photometric Local Universe Survey (J-PLUS) provides wide field-of-view (2 deg2) images in 12 narrow, intermediate and broad-band filters optimized for stellar photometry. Here we have applied J-PLUS data for the first time for the study of Galactic GCs using science verification data obtained for the very metal-poor ([Fe/H] ≈−2.3) GC M 15 located at ~10 kpc from the Sun. Previous studies based on spectroscopy found evidence of multiple stellar populations (MPs) through their different abundances of C, N, O, and Na. Our J-PLUS data provide low-resolution spectral energy distributions covering the near-UV to the near-IR, allowing us to instead search for MPs based on pseudo-spectral fitting diagnostics. Methods. We have built and discussed the stellar radial density profile (RDP) and surface brightness profiles (SBPs) reaching up to rtidal. Since J-PLUS FoV is larger than M 15’s rtidal, the field contamination can be properly taken into account. We also demonstrated the power of J-PLUS unique filter system by showing colour-magnitude diagrams (CMDs) using different filter combinations and for different cluster regions. Results. J-PLUS photometric quality and depth are good enough to reach the upper end of M 15’s main-sequence. CMDs based on the colours (u − z) and (J0378 − J0861) are found to be particularly useful to search for splits in the sequences formed by the upper red giant branch (RGB) and asymptotic giant branch (AGB) stars. We interpret these split sequences as evidence for the presence of MPs. Furthermore, we show that the (u − z) × (J0378 − g) colour–colour diagram allows us to distinguish clearly between field and M 15 stars, which is important to minimize the sample contamination. Conclusions. The J-PLUS filter combinations (u − z) and (J0378 − J0861), which are sensitive to metal abundances, are able to distinguish different sequences in the upper RGB and AGB regions of the CMD of M 15, showing the feasibility of identifying MPs without the need of spectroscopy. This demonstrates that the J-PLUS survey will have sufficient spatial coverage and spectral resolution to perform a large statistical study of GCs through multi-band photometry in the coming years.

SPECTRAL ENERGY DISTRIBUTIONS AND AGE ESTIMATES OF 39 GLOBULAR CLUSTERS IN M31

2009 ◽  
Vol 137 (6) ◽  
pp. 4884-4896 ◽  
Author(s):  
Jun Ma ◽  
Zhou Fan ◽  
Richard de Grijs ◽  
Zhenyu Wu ◽  
Xu Zhou ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Age Estimates

Spectral Energy Distributions and Age Estimates of 172 Globular Clusters in M31

2003 ◽  
Vol 125 (2) ◽  
pp. 727-741 ◽  
Author(s):  
Linhua Jiang ◽  
Jun Ma ◽  
Xu Zhou ◽  
Jiansheng Chen ◽  
Hong Wu ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Age Estimates

The Problem of Identifying and Modeling the Relationship between Monetary Factor and Inflation in the Russian Economy

2008 ◽  
pp. 61-76
Author(s):  
A. Porshakov ◽  
A. Ponomarenko
Keyword(s):  
Money Supply ◽  
Money Demand ◽  
Russian Economy ◽  
Long Run ◽  
Complex Approach ◽  
Wide Range ◽  
Long Time ◽  
The Relationship ◽  
Supply Side Factors

The role of monetary factor in generating inflationary processes in Russia has stimulated various debates in social and scientific circles for a relatively long time. The authors show that identification of the specificity of relationship between money and inflation requires a complex approach based on statistical modeling and involving a wide range of indicators relevant for the price changes in the economy. As a result a model of inflation for Russia implying the decomposition of inflation dynamics into demand-side and supply-side factors is suggested. The main conclusion drawn is that during the recent years the volume of inflationary pressures in the Russian economy has been determined by the deviation of money supply from money demand, rather than by money supply alone. At the same time, monetary factor has a long-run spread over time impact on inflation.

scholarly journals Planetary Nebulae in M31: Abundances, and comparison with bright Planetary Nebulae in the LMC

1997 ◽  
Vol 180 ◽  
pp. 475-476
Author(s):  
M. G. Richer ◽  
G. Stasińska ◽  
M. L. McCall
Keyword(s):  
Planetary Nebula ◽  
Luminosity Function ◽  
Large Population ◽  
Wavelength Region ◽  
Planetary Nebulae ◽  
Surprising Result ◽  
Population Synthesis ◽  
Abundance Distribution ◽  
Wide Range ◽  
The Mean

We have obtained spectra of 28 planetary nebulae in the bulge of M31 using the MOS spectrograph at the Canada-France-Hawaii Telescope. Typically, we observed the [O II] λ3727 to He I λ5876 wavelength region at a resolution of approximately 1.6 å/pixel. For 19 of the 21 planetary nebulae whose [OIII]λ5007 luminosities are within 1 mag of the peak of the planetary nebula luminosity function, our oxygen abundances are based upon a measured [OIII]λ4363 intensity, so they are based upon a measured electron temperature. The oxygen abundances cover a wide range, 7.85 dex < 12 + log(O/H) < 9.09 dex, but the mean abundance is surprisingly low, 12 + log(O/H)–8.64 ± 0.32 dex, i.e., roughly half the solar value (Anders & Grevesse 1989). The distribution of oxygen abundances is shown in Figure 1, where the ordinate indicates the number of planetary nebulae with abundances within ±0.1 dex of any point on the x-axis. The dashed line indicates the mean abundance, and the dotted lines indicate the ±1 σ points. The shape of this abundance distribution seems to indicate that the bulge of M31 does not contain a large population of bright, oxygen-rich planetary nebulae. This is a surprising result, for various population synthesis studies (e.g., Bica et al. 1990) have found a mean stellar metallicity approximately 0.2 dex above solar. This 0.5 dex discrepancy leads one to question whether the mean stellar metallicity is as high as the population synthesis results indicate or if such metal-rich stars produce bright planetary nebulae at all. This could be a clue concerning the mechanism responsible for the variation in the number of bright planetary nebulae observed per unit luminosity in different galaxies (e.g., Hui et al. 1993).

scholarly journals Polymorphic Iterable Sequential Effect Systems

2021 ◽  
Vol 43 (1) ◽  
pp. 1-79
Author(s):  
Colin S. Gordon
Keyword(s):  
Algebraic Structure ◽  
Position Effect ◽  
Type Systems ◽  
Sequential Effect ◽  
Prior Work ◽  
Sequential Effects ◽  
Wide Range ◽  
The Relationship ◽  
Categorical Semantics

Effect systems are lightweight extensions to type systems that can verify a wide range of important properties with modest developer burden. But our general understanding of effect systems is limited primarily to systems where the order of effects is irrelevant. Understanding such systems in terms of a semilattice of effects grounds understanding of the essential issues and provides guidance when designing new effect systems. By contrast, sequential effect systems—where the order of effects is important—lack an established algebraic structure on effects. We present an abstract polymorphic effect system parameterized by an effect quantale—an algebraic structure with well-defined properties that can model the effects of a range of existing sequential effect systems. We define effect quantales, derive useful properties, and show how they cleanly model a variety of known sequential effect systems. We show that for most effect quantales, there is an induced notion of iterating a sequential effect; that for systems we consider the derived iteration agrees with the manually designed iteration operators in prior work; and that this induced notion of iteration is as precise as possible when defined. We also position effect quantales with respect to work on categorical semantics for sequential effect systems, clarifying the distinctions between these systems and our own in the course of giving a thorough survey of these frameworks. Our derived iteration construct should generalize to these semantic structures, addressing limitations of that work. Finally, we consider the relationship between sequential effects and Kleene Algebras, where the latter may be used as instances of the former.

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