Photometry of the poorly studied galactic open star clusters King 13, King 18, King 19, King 20, NGC 136, and NGC 7245

We present the results of our BV R _c I _c CCD photometry for six Galactic open star clusters toward the Perseus spiral armperformed at the Special Astrophysical Observatory of the Russian Academy of Sciences. Based on these data and using JHK _s photometry from the 2MASS catalog, we have determined the ages, distances, and color excesses for the clusters: 710 Myr, 2960₋₃₄₀⁺⁴⁰⁰ pc, 0_· ^m 56 ± 0_· ^m 04 (King 13); 130 Myr, 3010₋₂₈₀⁺³⁰⁰ pc, 0_· ^m 69 ± 0_· ^m 04 (King 18); 560 Myr, 2630₋₂₇₀⁺³¹⁰ pc, 0_· ^m 69 ± 0_· ^m 08 (King 19); 160 Myr, 1750₋₇₀⁺⁸⁰ pc, 0_· ^m 77 ± 0_· ^m 05 (King 20); 250 Myr, 5220₋₃₂₀⁺³⁵⁰ pc, 0_· ^m 70 ± 0_· ^m 09 (NGC 136); 320 Myr, 3390₋₂₀₀⁺²¹⁰ pc, 0_· ^m 43 ± 0_· ^m 03 (NGC 7245).     

Selection,Statistics and Photometry of Compact Galaxies with Different Instrumental Equipment. Part I

On plates taken with 2 different photographic telescopes compact galaxies in 3 fields near M₃ and M₉₂ were selected. The integral magnitudes and maximum angular diameters of the compacts were determined. The RITCHEY -CHRéTIEN telescope of the FIGL Observatory for Astrophysics (FOA) with a focal ratio of 1:8.3 has a scale of 1 mm = 16.3, while the Tautenburg SCHMIDT with 1:3.2 has a scale of 1 mm ≌ 52°. From the selection statistics for both telescopes results nearly the same number of objects (50) up to 18^m.5 in V in a field of 1.5□°.60% of these objects are identical. An integral photometry on B plates of the same limiting magnitude from both telescopes leads to nearly the same brightness of objects, while they are o^m.5 fainter on FOA V plates. Because of its smaller focal ratio this telescope does not record the halo parts of the compacts. This is clearly demonstrated by the maximum equidensitometric diameters which on FAO plates are on the average only half of those determined on Tautenburg plates. A diameter magnitude diagram is shown.     

Search for LBV candidates in the M33 galaxy

A total of 185 luminous blue variable star (LBV) candidates with V<18_·^m 5 are selected based on the results of aperture photometry. The primary selection criterion is that the prospective candidate should be a blue star with Hα emission. In order not to overlook appreciably reddened LBV candidates, we compose an additional list of 25 red (0_·^m35< B − V < 1_·^m2, V < 18_·^m5) emission star candidates. A comparison with the list of known variables in the M33 galaxy showed 29% of our selected candidates to be photometrically variable. We also find our list to agree well with the lists of emission-line objects obtained in earlier papers using different methods.     

Catalog of equatorial coordinates and <Emphasis Type="Italic">B</Emphasis>-magnitudes of stars of the FON project

The catalog of equatorial coordinates α and δ and B-magnitudes of stars of the northern sky (from–4° to +90°) was created as a part of the FON project at the Main Astronomical Observatory of the National Academy of Sciences of Ukraine. The data accumulated in the Joint Digital Archive of the Ukrainian Virtual Observatory were used. The total number of processed plates is 2260. Astronegatives were digitized with Microtek ScanMaker 9800XL TMA and Epson Expression 10000XL scanners in the 1200 dpi scanning mode. The majority of plates have a size of 30 × 30 cm (13000 × 13000 pixels). The catalog contains the data on 19451751 stars and galaxies with B ≤ 16.5m at the epoch of 1988.1. The coordinates of stars and galaxies were obtained in the Tycho-2 reference system, and B-magnitudes were determined in the system of photoelectric standards. The mean internal errors of the catalog are σ_αδ = 0.23″ and σ_B = 0.14^m for all objects or σ_αδ = 0.10″ and σ_B = 0.07^m for stars in the B = 7^m–14^m range. The convergence between the catalog and Tycho-2 is characterized by the following values: 0.06′′ and 0.15^m. The mean-square difference in coordinates from the catalog and from UCAC-4 is σ_αδ = 0.30′′ (18 742 932 objects, or 96.36% of stars and galaxies, were cross-identified).     

Activity of the 1998 Leonid shower from video records

Abstract— Video observations of the Leonid shower aboard two aircraft in the 1998 Leonid multi-instrument aircraft campaign and from ground locations in China are presented. Observing at altitude proved particularly effective, with four times higher rates due to low extinction and low angular velocity at the horizon. The rates, derived from a total of 2500 Leonid meteors, trace at least two distinct dust components. One dominated the night of 1998 November 16/17. This two-day wide component was rich in bright meteors with r = N (m + 1)/N (m) ≈ 1.5 (s = 1.4) and peaked at an influx of 3.1 ± 0.4 × 10^?12 m^?2 s^?1 (for particles of mass <7 × 10^?5 g) at solar longitude Λ₀ ≈ 234.52 (Eq. J2000). The other more narrow component peaked on 1998 November 17/18 at Λ₀ = 235.31 ± 0.01. Rates were elevated above the broad component between Λ₀ = 235.15 and 235.40, symmetric around the current node of the parent comet 55P/Tempel-Tuttle, peaking at 5.1 ± 0.2 × 10^?12 m^?2 s^?1. The population index was higher, r = 1.8 ± 0.1 (s = 1.7), but not as high as in past Leonid storms (r = 3.0). The flux profile of this component has an unusual asymmetric shape, which implies a blend of contributions from at least two different but relatively recent epochs of ejection. The variation of r across the profile might be due to mass-dependent ejection velocities of the narrowest component. High rates of faint meteors occurred only in an isolated five-minute interval at Λ₀ = 235.198, which is likely the result of a single meteoroid breakup in space.     

A dwarf nova in Taurus

In searchs for flare stars in the vicinity of the Pleiades cluster, three flares were detected in 1970,1972, and 1977 in a star with the coordinates α ₁₉₅₀ = 3 ^h 48 ^m ·9, δ _l950 = 25‡15’.8. The star’s brightness at a minimum is >21 ^m ·5. The star was tentatively assigned to the U Gem type. To confirm this assumption, we examined photographic plates for the period of 1947–1987. As a result, we found 12 more flares. The average recurrence time based on the 1963–1977 observations is about 330 days, and the maximum flare amplitude is >6 ^m .Narrow superflares and steady-state flares lasting over 40 days have been observed in the star. The results show that this is a dwarf nova of the UGSU subtype. Translated from Astrofizika, Vol. 42, No. 1, pp. 47–52, January–March, 1999.     

Optical properties of single-component zodiacal light models

To provide material for interpretations of forthcoming zodiacal light measurements the characteristics of 468 single-component, in-ecliptic models are summarized in two survey diagrams. The models are based on Mie theory and on a power law dn ∞ r^?γα^?kdα for the dependence of the particle number density n on solar distance r and on the size parameter α (circumference/wavelength). The size range involves particles with α_min ≤ α ≤ 120; (α_min = 1,2,4,10,60), flat (k = 2·5) and steep (k = 4) size spectra, and complex refractive indices m = m₁ ? m₂i with m₁ = 1·33; 1·5; 1·7 and m₂ = 0; 0·01; 0·05; 0·1.The models suggest that the spatial variation of dust particle number densities should be less than about ∞ r^?0·5 in the ecliptic plane. Either dielectric particles of tenth-micron size or absorbing particles of half-micron size or very slightly absorbing particles of some tens of microns in size are able to produce polarization that agrees in sign and location of the maximum with the observations. Ambiguities can only be removed by considering intensity and polarization over a wide range of wavelengths.     

Lymanα forests and the evolution of the universe

The Lyα forest absorption lines in the spectra of quasars are interpreted as caused by the crossings of the light beam with the walls of a bubble structure (expanding with the Hubble flow only). Then, the typical separation between the absorption lines is proportional to the mean size of the bubbles. The variable factor is the expansion rate H[z]. The Friedmann regression analysis of the observed line separations determines the density parameter ω₀ and the normalized cosmological term λ₀ = λc²/3H²₀ of the appropriate cosmological model: ω₀ = 0.014 ± 0.002, λ₀ = 1.080 ± 0.006. Depending on the Hubble parameter this method reveals the values of the present mean matter density pm,0 = 2.6 h² · 10⁻²⁸ kg m⁻³ and of the cosmological constant Λ = 3.77 h² · 10⁻⁵² m⁻² (with h = H₀/(100 km/s·Mpc)). According to our analysis all models with Λ = 0 must be excluded. The curvature of space is positive. The curvature radius R₀ is 3.3 times the Hubble radius (c/H₀). The age t₀ is 2.8 times the Hubble age (H₀⁻¹).     

VV Orionis – improved elements

TheUBV light curves obtained by Duerbeck (1975) andHa (wide) and Ha (narrow) light curves obtained by Chambliss & Davan (1987) of the detached eclipsing binary VV Orionis (VV Ori) were analysed using the Wilson-Devinney method fixing the two parametersT _h (25,000 K) and q(0.4172), resulting in the following absolute elements:A = 13.605 ± 0.03 LR_⊙,R _h = 5.03 ±0.03R _⊙, R_c = 2.43 ±0.02R _⊙,M _bol,h = -5.18 ± 0.11,M _bol,c = -1.54 ± 0.06,m _h =10.81 + 0.42m _⊙ andm _c = 4.51 ± 0.41m _⊙. The de-reddened colours obtained from applying the reddening corrections ofE(B-V) = 0^m.05 andE(U-B) = O ^m .04, and the derived temperatures of the components, gave spectral types ofB 1.5V for the primary and 54-5V with anUV excess of 0 ^m ·3 for the secondary component. A comparison of the logL and logT _e of the components with the observed ZAMS shows the primary component to be a little above and the secondary component to be a little below/or on the ZAMS. A comparison of the properties of the components of VV Ori and a few other detached systems with the normal stars in the logL, logR and logT _e versus logm planes, indicated a need for either a readjustment of the scales of the above parameters or modifications in the theoretical models. From the position of the components on the evolutionary tracks of Pop I composition computed by Schaller et al. (1992) it is noticed that while the primary component of W Ori had slightly evolved along the main-sequence, its secondary is still unevolved. The age of VV Ori is found to be 10 ± 1 million years and it is at a distance of 368 ± 10 pc.     

Total-to-selective extinction ratio in nearby and distant objects

In an area of nearly 23.1 square degrees centered at α(1950) = 23^h57^m and δ(1950) = + 59δ48' magnitudes, colors, and spectral classes were determined for 1419 stars brighter than m_pg = 13^m.00. Star counts were made in this area for all objects brighter than m_pg = m_pv = 15^m.5. Altogether 50585 stars were included in the pv counts. The original photographic data have been transformed to the B, V system. From star counts the ratio of total-to-selective extinction was derived to be R ≉ 4.0 ± 0.2. It depends on the distance to the stars under consideration as well as on the surface density of the objects inside the considered region. In einem Gebiet von annähernd 23.1 Quadratgrad mit den Mittelpunktskoordinaten α(1950) = 23^h57^m und δ(1950) = 59°48' werden für 1419 Sterne heller als m_pg = 13^m.00 Helligkeiten, Farben und Spektraltypen bestimmt. Sternzählungen in Helligkeitsintervallen m_pg und m_pv wurden für alle Objekte heller als m_pg = m_pv = 15^m.5 durchgeführt. Für diese 50585 Sterne wurden die gemessenen photographischen und photovisuellen Helligkeiten in das B, V-System transformiert. Im Ergebnis dieser Sternzählungen wurde ein Wert von R ≉ 4.0 ± 0.2 abgeleitet. Er hängt sowohl von der Entfernung der betrachteten Objektgruppen als auch von der Flächendichte der Sterne innerhalb der Region ab.     

The Diameter of (106) Dione

The mean diameter D = 147 ± 3 km of (106) Dione is derived from visual observations in Denmark, Germany and the Netherlands of the occultation of AGK₃ + 25°0989 on 1983 January 19. Photoelectric magnitudes are: B(1, 2°.4) = 8^m.51 ± 0^m.06 and B – V = 0^m.65 ± 0^m.07. The visual albedo is pv = .064. Constraints on the axis of rotation are derived from the observed elliptical contour.     

Orbite de l'etoile double visuelle ADS 1538 = Σ 186

The physical and orbital elements of the binary star ADS 1538 = Σ 168 (α₁₉₀₀ = 01^h50^m.7, δ₁₉₀₀ = +01°21'; α₂₀₀₀ = 01^h55^m·8, δ₂₀₀₀ = +01°51') are determined. The absolute visual magnitudes of the two components are 4^m.04 resp. 4^m.17, the masses 1.34 M_⊙ resp. 1.29 M_⊙.     

Catalog of positions and <Emphasis Type="Italic">B</Emphasis>-magnitudes of stars in the circumpolar region of the Northern Sky Survey (FON) project

The catalog of equatorial coordinates α and δ and B-magnitudes of stars has been created at the Main Astronomical Observatory, National Academy of Sciences of Ukraine (MAO NASU), for the circumpolar region (from 58° to 90°) of the Northern Sky Survey (FON) project within the work on the rational use of resources accumulated in the JDA (Joint Digital Archive) of the Ukrainian Virtual Observatory (UkrVO). The total number of processed plates is 477. The plates were digitized with the using Microtek ScanMaker 9800XL TMA and Epson Expression 10000XL scanners (scanning mode was 1200 dpi, the linear size of plates was 30 × 30 cm or 13000 × 13000 px). The catalog includes 1 975 967 stars and galaxies with B of up to 16.5 ^m as of the epoch of 1985.28. The coordinates of stars and galaxies were obtained in the Tycho-2 reference system and B-magnitudes were obtained in the system of photoelectric standards. The internal errors of the catalog for all the objects are σ_αδ = 0.23′′ and σ _B = 0.12 ^m , and those for stars of the B range from 8 ^m –14 ^m , 0.11′′ and 0.06 ^m , respectively. The convergence between the calculated and reference positions is σ_αδ = 0.06′′ (for 171124 stars from Tycho-2), and that between the photoelectric stellar B-magnitudes is σ _B = 0.15m (for 5130 stars). The external error from the comparison with UCAC-4 are σ_αδ = 0.33′′ (1928367 stars and galaxies have been cross identified).     

Schmidt plate survey in the galactic centre direction. 1. Investigation of open clusters in the Sagittarius-Carina spiral arm

A study of four open clusters on Tautenburg Schmidt plates in the direction to the Galactic Centre (l = 17.0°, b = +0.8°) is presented. In a field of 8.95 square degrees proper motions and B, V magnitudes were determined for about 36 500 stars up to the limiting magnitudes B = 17^m.9, V = 16^m.8. For stars brighter than B = 16^m an accuracy of about 3 mas/year has been estimated for proper motions. The rms errors of stellar magnitudes and (B—V) colours is about 0.1 mag. There are two open clusters already known in this sky area: Trumpler 32 (C 1814-133) and NGC 6611 (C 1816-138). By the inspection of the plates two additional anonymous clusters were identified near the double star ADS 11285 or BD −14°5014 (C 1819-146) and near the star BD −14°5016 (C 1820-146). The cluster membership determination was carried out using information on spatial and proper motion distributions of stars in the field. The colour-magnitude diagrams up to the limiting stellar magnitude were constructed. For each cluster interstellar extinction A_V, diameters of the core and corona, ages and spatial velocity components (V, W) relative to the LSR in the Y, Z-galactic directions were derived. The distances to the clusters were obtained to 1720 pc, 2260 pc, 2130 pc and 2130 pc for Trumpler 32, NGC 6611, C 1819-146 and C 1820-146, respectively. All clusters are situated in the Sagittarius-Carina spiral arm. Their spatial location confirms the assumption that galactic spiral arms are close to logarithmic spirals with a characteristic angle of about 20 degrees.     

Polar-ring galaxies: New candidates and statistics

We present the results of our observational study of two candidates for polar-ring galaxies (PRGs). Both objects, A2330-3751 and SDSS J000911.57-003654.7, are giant edge-on galaxies with large-scale structures resembling polar rings observed along their minor axes. The optical diameter of the putative ring reaches 60 kpc in A2330-3751 and 18 kpc in SDSS J000911.57-003654.7. To estimate the space density of PRGs, we have constructed their luminosity function in the range of B-band absolute magnitudes from −17_· ^m 5 to −21_· ^m 5. We have found that ∼10⁻³ of the nearby galaxies exhibit polar structures. Polar rings around early-type (E/S0) galaxies are encountered approximately a factor of 3 more frequently than those around spiral ones. According to our estimates, ∼20–30 PRGs in which large-scale rings are seen almost face-on must be observed among relatively bright galaxies (B ≤ 15 ^m ).     

An Unusual Group of Low Surface Brightness Galaxies in the Region 1046 + 65

Eine Gruppe von 11 Galaxien mit einer Flächenhelligkeit von etwa 26 mag/□” wurde in Richtung der M81-Gruppe entdeckt. Unter der Annahme gleicher Entfernung wie die M81-Gruppe stimmen ihre linearen Durchmesser (2–3 kpc) und ihre absoluten Helligkeiten (M_B = -11^m bis -12^m mit den Parametern der Zwerggalaxien der Lokalen Gruppe überein. Annahmen über die Stabilität der Zwerggruppe gegenüber M81 erlauben eine Abschätzung ihrer Gesamtmasse zu ℜ ≳ 1 · 10⁸ M ⊙ und ihres Masse-Leuchtkraftverhältnisses ℜ/L ≳ 1.2 (in Sonneneinheiten).     

THE BM Ori system. IV. A new component of the system

Cross correlations between observed and synthetic spectra are used to discover yet another satellite of BM Ori with the following characteristics: effective temperature T_eff = 4000 K, radius R = 16R_⊙, mass M = 1.8M_⊙, spectral type K7 III, absolute bolometric stellar magnitude M_b = + 4^m·0, axial rotation velocity V sini = 85 km/s, and relative luminosity 0.005 near the V band. __________ Translated from Astrofizika, Vol. 49, No. 1, pp. 111–120 (February 2006).     

Schmidt plate survey towards the Galactic centre. 2. Stellar statistics in the direction of the Sagittarius-Carina arm

A study of the structure and kinematics of the Galaxy from Tautenburg Schmidt plates taken towards the Galactic centre (l = 17.0°, b = +0.8°) is presented. Proper motions and B, V magnitudes were determined for about 36 500 stars up to the limiting magnitude V = 16^m.8 in a field of 8.95 square degrees. Proper motion accuracy of about 3 mas/year has been obtained for stars brighter than V = 15^m. The rms errors of stellar magnitudes and (B–V) colours is about 0.1 mag. The majority of field stars in the survey are main sequence stars and red giants of the disk. They belong to the Local or Sagittarius-Carina arms, or they are located between these spiral arms. Comparing the modelled and observed distributions of magnitudes and colours, we specified the interstellar extinction determined in the preceding study of open clusters in this field. The luminosity function towards the Galactic centre was determined for stars with absolute magnitudes from -4^m.35 to +9^m. Kinematical and spatial distribution parameters up to 4 kpc from the Sun were obtained as a function of galactocentric distance.     

NGC 4650 A: A nearly edge-on ring galaxy?

The peculiar galaxy NGC 4650 A (α=12^h 42^m. 1; = δ—40° 26′; 1950·0) has been studied by means of direct and spectral observations with the ESO 3·6-m telescope. It is interpreted as a prolate, elliptical galaxy surrounded by a warped ring of H II regions, dust and stars. The distance is 47 Mpc (H ₀=55 km s⁻¹ Mpc⁻¹). The ring is seen nearly edge-on (inclination 85°) and it rotates. It has a diameter of about 21 kpc and is bluer than the elliptical galaxy for which the (M/L _v) ratio is ∼12 in solar units. The observed configuration may be the result of interaction with the nearby galaxy, NGC 4650.     

Optical identification of IRAS point sources based on low-dispersion spectra from the First Byurakan Survey. V

Part five of optically identified point sources from the IRAS Point Source Catalog (PSC) contains data on 19 late-type stars. The identifications were based on the Digitized Sky Survey (DSS), the First Byurakan Survey (FBS), blue and red maps of the Palomar survey (POSS), and infrared fluxes at 12, 25, 60, and 100 mm in the region of +61° ≤ δ ≤ +65° and 05 ^h 30 ^m ≤ α ≤ 18 ^h 35 ^m with an area of 357 sq. deg. Of the 76 objects given in the IRAS PSC as unidentified sources of infrared radiation, 51 are associated with known stars in existing catalogs, 6 are objects from the FBS of late-type stars, and 19 sources remained unknown in the optical range. For the identified stars we determined the optical coordinates, their departures from the IR coordinates, the Vstellar magnitudes, the color indices CI,and the preliminary spectral subtypes. The objects have optical magnitudes in the range of 8 ^m −16 ^m .Gas-dust shells are assumed to exist around four of the sources. Finder charts from the DSS are given for 19 of the objects. Translated from Astrofizika, Vol. 42, No. 1, pp. 53–59, January–March, 1999.