ABSTRACT This paper presents the results of analysing the integrated light (IL) low-resolution spectra of globular clusters (GCs) in the M31 and Centaurus A groups of galaxies. The sample consists of eight very metal-poor GCs ($\rm [Fe/H]\le -2$ dex) with high signal-to-noise ratio spectra acquired with the telescopes: the 6-m SAO RAS (BTA), the Southern African Large (SALT), and the 6.5-m Magellan (MMT). We study the influence of contribution of the horizontal branch stars on the hydrogen Balmer line profiles in the IL spectra. By modelling the Balmer lines, as well as the metal lines in the observed spectra, we determine the optimum parameters of stellar evolution isochrones and, consequently, the parameters of the atmospheres of the cluster stars. For all the studied GCs, the parameters of horizontal branch stars set by the selected isochrones, the corresponding ages, and carbon abundances are presented for the first time. The abundances of several other elements (Mg, Ca, Ti, Cr, and Mn) were determined for five GCs for the first time. All the studied GCs have blue horizontal branches and are older than 10 Gyr. Their chemical abundances, with the exception of Mg and Mn, are in good agreement with the abundances of stars in the Galactic field. The reasons of low [Mg/Fe] and of high [Mn/Fe] are discussed. Study of the fundamental properties of stellar populations in old GCs facilitates a better understanding of the formation processes of their parent galaxies and nucleosynthesis in the early Universe.

Results of surface photometry of 50 galaxies in the Local Volume based on archived images obtained with the Hubble Space Telescope are presented. Integrated magnitudes in the V and I bands are introduced for the chosen galaxies, along with brightness and color profiles. The obtained photometric parameters are compared with the measurements of other authors.

Представлены результаты поверхностной фотометрии 50-ти галактик в Местном объеме на основе архивных изображений, полученных на космическом телескопе Хаббла. Для выборки галактик приводятся интегральные величины в полосах V и I, а также профили яркости и цвета. Проведено сравнение полученных фотометрических параметров с измерениями других авторов. The results of surface photometry of 50 galaxies in the Local Volume based on archival images obtained with the Hubble Space Telescope are presented. For the sample of galaxies, the integrated magnitudes in the V and I bands are given, as well as the brightness and color profiles. The obtained photometric parameters are compared with the measurements of other authors.

ABSTRACT A method is proposed for determining the properties of Type Ia supernovae from short-lived precursors – Prompt SNIa. This method is based on the assumption that this subtype of Type Ia supernovae exploded into low-metallicity globular clusters (GCs), and is responsible for the enrichment of the high-metallicity subgroup of GCs and circumgalactic clouds (CGCs) with the iron peak elements. We justify that CGCs are the formation places of GCs of both subgroups. The accuracy of the method depends, first, on the number of GCs, the spectra of which have been studied in detail, and second, on the number of chemical elements, the abundances of which have been worked out. Only those elements are of interest for this method that are produced in supernova explosions and are not produced at the previous stage of the stellar evolution. Our estimates of nucleosynthesis in low-metallicity supernova GCs are in the best agreement with the following Prompt SNIa model: Single Degenerate Pure Deflagration Models of white dwarfs (WDs) burning with masses in the range from $\rm 1.30$ to $1.31\, {\rm M}_{\odot}$ if carbon explodes in the centre of a WD with a low central density from $\rm 0.5 \times 10^9$ to $\rm 10^9\, {\rm g\,cm^{-3}}$ (Leung & Nomoto 2018).

This paper presents the results of the analysis of the integrated-light spectra of eight Galactic globular clusters with a relatively low luminosity and stellar density: Palomar 1, Palomar 2, Palomar 10, Palomar 13, Palomar 14, NGC 6426, NGC 6535, and NGC 6749. The absorption spectral indices in the Lick system were measured in their spectra, as well as in the spectra of bright clusters: NGC 7006, NGC 6229, NGC 6779, NGC 6205, NGC 6341, and NGC 2419. The age, metallicity, and approximate abundance of the $$\alpha $$ -process elements were determined for eight objects under study. The material of the study was the archival observational data of the 1.93-m telescope of the Haute-Provence Observatory. For seven out of eight objects, galactic analogs with close values of the Lick indices within the limits of their determination errors were found. The coincidence of the Lick indices implies the similarity of age and chemical composition. The available literature data confirm our conclusions regarding the similarity of the properties of the clusters’ stellar populations. According to the literature data on the spatial position and motion of objects, the objects of study turned out to belong, as a rule, to the same subsystems of the Galaxy as their analogs. No globular clusters with a complete set of Lick indices similar to those of Palomar 1 were found, which supports the literature conclusions about its possible extragalactic origin. Our photometry of stars in the VLT images and the Gaia DR3 data allowed us to estimate the metallicity, age, color excess, and distance for Palomar 10. The Gaia DR3 data for NGC 6426 were analyzed.

In this work a search was carried out for globular clusters belonging to the Sagittarius (Sgr) tidal stream using the analysis of spatial positions, radial velocities relative to the Galactic Standard of Rest (V_{GSR}),proper motions and ratio of "age -- metallicity" ([Fe/H]) for globular clusters and for stars in the tidal stream. As a result, three categories of globular clusters were obtained: A -- most certainly in the stream: Terzan 8, Whiting 1, Arp 2, NGC 6715, Terzan 7, Pal 12; B -- kinematic outliers: Pal 5, NGC 5904, NGC 5024, NGC 5053, NGC 5272, NGC 288; C -- lowest rank candidates: NGC 6864, NGC 5466, NGC 5897, NGC 7492, NGC 4147.

We take a closer look at our published results of determination of ages, metallicities, helium mass fractions and abundances of chemical elements in Galactic globular clusters in order to find possible signatures of the phenomenon of multiple stellar populations in these data. Our analysis reveals that carbon abundances in the atmospheres of stars in the studied clusters change gradually during their evolution. The changes of the helium mass fraction and C, O, Mg and Na abundance anomalies caused by the effect of multiple stellar populations on the analyzed integrated-light spectra are detected through the comparison of our results with models of chemical evolution and literature data for Galactic field stars.

The established by us possibility to consider circumgalactic clouds (CGCs) as the remnants of the parent clouds in which globular clusters (GCs) have been formed (Acharova Sharina 2018) is based on a comparison of the following facts. First, the metallicities of CGCs at redshifts z <1 and of GCs in our and other galaxies show a bimodal distribution with a minimum near [Mg/H]=-1. Mean values and standard deviations of the Mg abundances in GCs and CGCs with [Mg/H]<-1 and [Mg/H]> -1 coincide within the typical error of measuring the elemental abundances in clouds: 0.3 dex (Acharova Sharina 2018). Second, a similar coincidence is observed for GCs and CGCs with [X/H]<-1 and [X/H]> -1 at redshifts 2

We present the results of determination of the age, helium mass fraction (Y), metallicity ([Fe/H]), and abundances of the elements C, O, Na, Mg, Ca, Ti, Cr and Mn for 26 globular clusters of the Galaxy. In this work, we apply a method developed by us that employs medium-resolution integrated-light spectra of globular clusters and models of stellar atmospheres and it is supplemented in this paper by the automatic calculation of microturbulence velocities of stars in the studied objects. Based on the data obtained for 26 objects, as well as the results of our previous studies, it is shown that the abundances of chemical elements that we measured, with the exception of carbon, are consistent with the literature estimates from the analysis of integrated-light spectra of clusters and from high-resolution spectroscopic observations of their brightest stars. Our estimates of [C/Fe] are consistent with the literature values obtained from the integrated-light spectra of clusters. We interpret the systematic difference between the derived [C/Fe] for globular clusters and the literature [C/Fe] values for the brightest stars of the clusters as a change of the chemical composition in the atmospheres of stars during their evolution. The estimated absolute ages and average Y for the clusters are in a reasonable agreement with the literature data from the analysis of color–magnitude diagrams of the objects.

The study of ages, helium mass fraction (Y) and chemical composition of globular clusters in dwarf galaxies is important for understanding the physical conditions at the main evolutionary stages of the host galaxies and for constraining the build-up histories of large galaxies. We present the analysis of integrated-light spectra of 8 extragalactic and 20 Galactic globular clusters (GCs) using our population synthesis method. We calculate synthetic spectra of GCs according to the defined stellar mass functions using model atmospheres and stellar parameters ($[Fe/H]$, $T_{eff}$, and $log g$) set by theoretical isochrones. The main advantage of our method is the ability to determine not only chemical composition but also the age and mean Y in a cluster by modelling and analysis of Balmer absorption lines. The knowledge of Y and anomalies of light elements in star clusters is one of the key points for understanding the phenomenon of multiple stellar populations.

AbstractWe compare the properties of stellar populations for globular clusters (GCs) and field stars in two dwarf spheroidal galaxies (dSphs): ESO269-66, a close neighbour of NGC5128, and KKs3, one of the few isolated dSphs within 10 Mpc. We analyse the surface density profiles of low and high metallicity (blue and red) stars in two galaxies using the Sersic law. We argue that 1) the density profiles of red stars are steeper than those of blue stars, which evidences in favour of the metallicity and age gradients in dSphs; 2) globular clusters in KKs3 and ESO 269-66 contain 4 and 40 percent of all stars with [Fe / H] ~ 1.6 dex and the age of 12 Gyr, correspondingly. Therefore, GCs are relics of the first powerful star-forming bursts in the central regions of the galaxies. KKs 3 has lost a smaller percentage of old low-metallicity stars than ESO269-66, probably, thanks to its isolation.

Moderate resolution spectra of four globular clusters in the dwarf spheroidal galaxy IKN obtained with the 6-m telescope of the Special Astrophysical Observatory have been used to determine the radial velocities, ages, and metallicities of the clusters, and also to derive the first approximate estimates of the abundances of Mg, Ca, and C. Cross-correlation with radial-velocity standards, fitting of the observed spectra with model spectra, diagnostic diagrams based on the Lick absorption indices, and comparison of the spectra and absorption indices with those of Galactic globular clusters are applied. The integrated spectrum of the two bright clusters IKN4 and IKN5, which are close to the center of the galaxy in projection on the celestial sphere, yields the heliocentric radial velocity Vh = 38 ± 30 km/s, age T =12.6 ± 2 Gyr, metallicity [Fe/H] = −2.1 ± 0.2 dex, and abundance of α-process elements [α/Fe] ∼ 0.5 dex. The integrated spectrum of the two weaker clusters IKN1 and IKN3, which are far from the center of the galaxy, yielded the radial velocity Vh = −39 ± 50 km/s. Despite the low signal-to-noise ratio in the integrated spectrum for IKN1 and IKN3, all the analysis methods applied indicate that these two objects have approximately the same age and metallicity as IKN4 and IKN5. According to the measured Lick indices $${{\rm{H}}_{\delta {\rm{F}}}}$$ and Hβ, the studied globular clusters in IKN have blue horizontal branches.

We compare the properties of the stellar populations of the globular clusters and field stars in two dwarf spheroidal galaxies (dSphs): ESO 269-66, a near neighbor of the giant S0 galaxy NGC 5128, and KKs 3, one of the few extremely isolated dSphs within 10 Mpc. The histories of star formation in these galaxies are known from previous work on deep stellar photometry of images from the Hubble Space Telescope (HST). The age and metal content for the nuclear globular clusters in KKs 3 and ESO 269-66 are known from published spectroscopic studies: T = 12.6 billion years, Fe/H] = -1.5, and -1.55 dex. We use the Sersic function to construct and analyze the profiles of the surface density of the stars with high and low metallicities (red and blue) in KKs 3 and ESO 269-66, and show that (1) the profiles of the density of red stars are steeper than those of blue stars, which is indicative of gradients of metallicity and age in the galaxies, and (2) the globular clusters in KKs 3 and ESO 269-66 contain roughly 4 and 40%, respectively, of all the old stars in the galaxies with metallicities [Fe / H] ~ -1.5 ÷ -1.6 dex and ages of 12-14 billion years. The globular clusters are, therefore, relicts of the first, most powerful bursts of star formation in the central regions of these objects. It is probable that, because of its isolation, KKs 3 has lost a smaller fraction of old low-metallicity stars than ESO 269-66. Keywords: galaxies: dwarf- galaxies: star clusters- galaxies: KKs 3, ESO 269-66

Deep stellar photometry of one of the most distant Galactic globular clusters, Palomar 3, based on frames taken with the VLT in Johnson-Cousins broadband V and Ifilters is presented, together with medium-resolution stellar spectroscopy in the central region of the cluster obtained with the CARELEC spectrograph of the Observatoire de Haute Provence and measurements of the Lick spectral indices for the integrated spectrum. Computations of the orbital parameters of Palomar 3 and nine Galactic globular clusters with similar metallicities and ages are also presented. The orbital parameters, age, metallicity, and distance of Palomar 3 are estimated. The interstellar absorption is consistent with and supplements values from the literature. The need to obtain more accurate data on the proper motions, ages, and chemical compositions of the cluster stars to elucidate the origin of this globular cluster is emphasized.

We present the results of determinations of age, helium abundance (Y), metallicity ([Fe/H]), and estimations of abundances of the elements: C, N, O, Mg, Ca, Ti, Cr, Ni, Sr, and Ba of four globular clusters in the neighborhood of the Andromeda galaxy ([SD2009]GC7,Mayall II, Mackey-GC1 (MGC1), and Bol 298 (MGC6)) and of six Galactic clusters. Medium-resolution long-slit integrated-light spectra from the clusters under study were used to determine the parameters.Observations of extra-galactic objects were carried out with the 6-m SAO RAS telescope using the SCORPIO-1 multimode focal reducer. Galactic globular clusters NGC6341 (M92), NGC6838 (M71), and NGC7078 were observed with the CARELEC spectrograph at the 1.93-m telescope of the Haute-Provence Observatory. The integratedlight spectra of Galactic globular clusters NGC104, NGC6121 (M4), and NGC7078 (M15) were taken from the spectral library by Schiavon.We selected the best isochrone for each cluster by comparison of the shapes and intensities of the observed and theoretical Balmer line profiles.

The abundance of alpha elements and iron in stars of globular clusters shows the composition of the gaseous medium, in which they have been formed. In the present paper, we discuss a possibility to consider dense clouds of circumgalactic gas (partial Lyman limit systems and Lyman limit systems) observed in the 100 - 130 kpc neighbourhood of galaxies at redshifts of 0.1<z<1.1 as being the residual parts of clouds, in which globular clusters have been formed. Conclusions have been drawn based on statistical analysis of the abundance of magnesium and iron in globular clusters and in circumgalactic clouds and on the spatial location of objects of both types.