Metallicities and ages of stellar populations at a high Galactic latitude field

We present an analysis of UBVRI data from the selected area SA 141. By applying recalibrated methods of measuring ultraviolet excess (UVX), we approximate abundances and absolute magnitudes for 368 stars over 1.3 deg² out to distances over 10 kpc. With the density distribution constrained from our previous photometric parallax investigations and with sufficient accounting for the metallicity bias in the UVX method, we are able to compare the vertical abundance distribution to those measured in previous studies. We find that the abundance distribution has an underlying uniform component consistent with previous spectroscopic results that posit a monometallic thick disc and halo with abundances of  [Fe/H]=−0.8  and −1.4, respectively. However, there are a number of outlying data points that may indicate contamination by more metal-rich halo streams. The absence of vertical abundance gradients in the Galactic stellar populations and the possible presence of interloping halo streams would be consistent with expectations from merger models of Galaxy formation. We find that our UVX method has limited sensitivity in exploring the metallicity distribution of the distant Galactic halo, owing to the poor constraint on the UBV properties of very metal-poor stars. The derivation of metallicities from broad-band UBV photometry remains fundamentally sound for the exploration of the halo but is in need of both improved calibration and superior data.     

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.     

Investigations of Stephenson's Hα stars

Hitherto unstudied objects from Stephenson's list of Hα emission line objects at high galactic latitude were observed spectroscopically to prove their nature. 9 out of 11 objects show Hα in emission. Spectroscopy combined with photometric information indicates most of them being classical Be stars, while one object is a Post‐AGB star and one a T‐Tauri star. The classification of two objects, which are showing Hα in emission, is unclear. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

First Byurakan Spectral Sky Survey. Stars of late spectral types. −11° ≤ δ ≤ −7° belt

A 10th list of late-type M and C stars found on plates of the First Byurakan Spectral Sky Survey in the − 11° ≤ δ ≤ − 7° belt with an area of about 1070 deg² is given. The list contains data on 169 red stars, 117 of which were found for the first time: 8 are new C stars, 3 are Cstar candidates, 104 are M stars, 1 is either an M or an S star, and 1 object on the survey plate cannot be classified. Of the 117 objects, 47 are unidentified IRAS sources. A statistical analysis of the objects that are and are not identified with IRAS sources shows that the identified stars are, with a high probability, brighter and have relatively more massive envelopes. Two stars were found to have fairly large brightness variability (with an amplitude of at least 6^m.O). Gasdust shells are assumed to exist around nine of the IRAS sources. The equatorial coordinates, spectral types, and stellar magnitudes, determined on Palomar E maps, are given for the selected objects. Translated from Astrofizika, Vol. 41. No. 4, pp. 545–559, October–December, 1998.     

First Byurakan Spectral Sky Survey. Blue Stellar Objects. XII. The Region -3° ≤ δ ≤ +1°

The twelfth list of blue stellar objects in the second part of the First Byurakan Spectral Sky Survey (FBS) is presented. This list contains 143 objects in the region -3° +1° at high latitudes with an area of approximately 992 square degrees (62 fields). The objects have magnitudes V of 11.8-18.1 and B-V colors ranging from -0.82 to +0.81. Of the 143 objects, 51 have been discovered for the first time. Equatorial coordinates, V magnitudes, color indices, and preliminary classifications of the objects are given. DSS identification charts are given for the newly discovered objects.     

The First Byurakan Spectral Sky Survey. Late-type stars. VI. The zone+69°≤δ≤+77°

We present the sixth list of red stars selected from the plates of the First Byurakan Spectral Sky Survey. These objects are located in the zone3 ^h 45 ^m 18 ^h and+69°+77°. The list contains data on 42 new objects. We suggest that there exists a dust cloud around 2 of them.Translated fromAstrofizika, Vol. 38, No. 2, 1995.     

Investigation of faint Galactic carbon stars from the First Byurakan Spectral Sky Survey. II

Using recent astronomical databases, we investigate the characteristics of a list of new Galactic carbon (C) stars. These stars were discovered on the First Byurakan Spectral Sky Survey (FBS) plates and constitute the second part of our search for such objects. This second list of FBS C stars contains 44 objects. Slit spectra obtained by us with the BAO 2.6-m telescope confirm the carbon-rich nature of all of them. The list comprises 12 N-type carbon stars and 32 CH-type stars. We consider spectral types, B and R magnitudes retrieved from the USNO-B1.0 catalog, and JHK_s near-infrared photometry for stars extracted from the 2MASS point-source catalog. The R magnitudes of our objects are in the range 10 to 14. We derive distance estimates for all objects and find that most of the stars are located between approximately 3 and 20 kpc from the Sun. Their heights above or below the Galactic plane are in the range 1.5 to 13.0 kpc. Published in Astrofizika, Vol. 49, No. 2, pp. 197–208 (May 2006).     

A new gravitational lens from the MUSCLES survey: ULAS J082016.1+081216

We present observations of a new double-image gravitational lens system, ULAS J082016.1+081216, of image separation 2.3 arcsec and high (∼6) flux ratio. The system is selected from the Sloan Digital Sky Survey (SDSS) spectroscopic quasar list using new high-quality images from the UKIRT (United Kingdom Infrared Telescope) Deep Sky Survey (UKIDSS). The lensed quasar has a source redshift of 2.024, and we identify the lens galaxy as a faint red object of redshift  0.803 ± 0.001  . Three other objects from the UKIDSS survey, selected in the same way, were found not to be lens systems. Together with the earlier lens found using this method, the SDSS–UKIDSS lenses have the potential to significantly increase the number of quasar lenses found in SDSS, to extend the survey to higher flux ratios and lower separations, and to give greater completeness which is important for statistical purposes.     

First Byurakan Spectral Sky Survey. Stars of late spectral types. ix. -15 ≤ δ ≤-11 ° belt

A ninth list of late-type M and C stars found on plates of the First Byurakan Spectral Sky Survey in the -15 ≤ δ ≤-11° belt is given. Of the 123 selected objects, 83 were found for the first time (82 M stars and one carbon star of an early R0–R1 subtype). Of the 83 objects found for the first time, 15 are unidentified IRAS sources. It is established that 15 associated objects belong to spectral type M. Some new data are also given for the x-ray source 2E0019.2 — 1247. The equatorial coordinates, spectral types, and stellar magnitudes in the red band are given for the selected objects.     

A pilot study of the radio‐continuum emission from MASH planetary nebulae

We report an Australia Telescope Compact Array (ATCA) radio‐continuum observations of 26 planetary nebulae (PNe) at wavelengths of 3 and 6 cm. This sample of 26 PNe were taken from the Macquarie/AAO/Strasbourg Hα PNe (MASH) catalogue and previous lists. We investigate radio detection quality including measured and derived parameters for all detected or marginally detected PNe from this combined sample. Some 11 objects from the observed sample have been successfully detected and parametrized. Except for one, all detected PNe have very low radio surface brightnesses. We use a statistical distance scale method to calculate distances and ionised masses of the detected objects. Nebulae from this sample are found tobe large (>0.2 pc in diameter) and highly diluted which indicates old age. For 21 PNe from this sample we list integrated Hα fluxes and interstellar extinction coefficients, either taken from the literature or derived here from the Balmer decrement and radio to Hα ratio methods. Finally, our detected fraction of the MASH pilot sample is relatively low compared to the non‐MASH sub‐sample. We conclude that future radio surveys of the MASH sample must involve deeper observations with better uv coverage in order to increase the fraction of detected objects and improve the quality of the derived parameters (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A comparison catalogue ofHii-regions

For complete information about the apparent distribution ofHii-regions along the whole galactic equator a Catalogue of 698 known emission nebulae is given on the basis of 13 lists and catalogues of these objects. The main catalogue used for the northern sky was that of Sharpless (1959) including 313 objects while the coverage of the southern sky can be characterized by a greater number of smaller catalogues represented in the first place by that of Rodgerset al. (1960) and that of Gum (1955). ForHii-regions, only optical data were taken into account.Where several authors describe the complex of nebulosities a more detailed specification of objects is preferred. The objects in the Catalogue are listed according to their right ascensions for 1950. As only three catalogues applied here give also the objects out of the belt ±15° around the galactic equator, the Catalogue is divided into two parts. The first (main) part contains 667 objects lying within this belt, the second contains 31 objects lying outside it. A Summary Table listing the objects from the two parts according to their galactic longitudes involving, in addition, the 50-yrs precession for every object is also added.An attempt was made not to repeat contingent errors present in the source-catalogues. The maps of the POSS were often used. Coincidences with SNR and planetaries were sought for independently of identifications given in the source-catalogues. The list of objects from the source-catalogues ofHii-regions excluded as SNR, planetaries and galaxies is also given.Astrophysics and Space Science Review Paper.     

Variable blue objects in Kapteyn Selected Area 94

We present a list of ultraviolet excess objects in the Palomar Schmidt field centred on Kapteyn Selected Area 94. All these objects were selected on the basis of optical variability. They can serve as quasar candidates.     

RATAN-600 7.6-cm deep sky strip surveys at the declination of the SS433 source during the 1980–1999 period. Data reduction and the catalog of radio sources in the right-ascension interval 7h ≤ R.A. < 17h

We use two independent methods to reduce the data of the surveys made with RATAN-600 radio telescope at 7.6 cm in 1988–1999 at the declination of the SS433 source. We also reprocess the data of the “Cold” survey (1980–1981). The resulting RCR (RATAN COLD REFINED) catalog contains the right ascensions and fluxes of objects identified with those of the NVSS catalog in the right-ascension interval 7 ^h ≤ R.A. < 17 ^h . We obtain the spectra of the radio sources and determine their spectral indices at 3.94 and 0.5 GHz. The spectra are based on the data from all known catalogs available from the CATS, Vizier, and NED databases, and the flux estimates inferred from the maps of the VLSS and GB6 surveys. For 245 of the 550 objects of the RCR catalog the fluxes are known at two frequencies only: 3.94 GHz (RCR) and 1.4 GHz (NVSS). These are mostly sources with fluxes smaller than 30mJy. About 65% of these sources have flat or inverse spectra (α > −0.5). We analyze the reliability of the results obtained for the entire list of objects and construct the histograms of the spectral indices and fluxes of the sources. Our main conclusion is that all 10–15 mJy objects found in the considered right-ascension interval were already included in the decimeter-wave catalogs.     

First Byurakan Spectral Sky Survey. Blue stellar objects. XI. Region +80 ≤ δ ≤ +90°

The eleventh list of blue stellar objects in the second part of the First Byurakan Spectral Sky Survey (FBS) is presented. The list consists of 64 objects located in the region +80 +90° and 2^h 08^m a 20^h 15^m. The objects haveV magnitudes in the range 12.3–17.4 andB–V color indices in the range -0.55-+0.55. Of the 98 objects, 56 are newly discovered. Tentative classifications are given for 28 objects, of which there is one planetary nebula, 6 possible quasars, 15 possible white dwarfs, and 6 possible cataclysmic variables. Two of the latter are possibly novae having erupted at the epoch of exposure of the FBS plates in this region.Translated fromAstrofizika, Vol. 39, No. 4, pp. 531–540, November, 1996.     

Spatial distribution of antisymmetrically-curved extragalactic radio-jets

In order to fine the observational restrictions for theoretical models explaining curvatures of extragalactic jets, tails, or lobes, a list of 365 objects has been extracted from published data. Radio sources exhibiting both jets curved in the same direction (called typeV) are equally frequent as those exhibiting them with opposite directions. Among the last antisymmetric types, two possibilities are considered: when jets draw a clockwise (typeS) or counterclockwise (typeN) image. TypesS andN are not only equally frequent as expected, but they do not have preferred locations in the sky. At least at large scales, once a jet is thrown out, it has an equal chance to be sent in any direction, independently of the one followed by its twin counterjet.     

A plea for better astrophysical and astrometric data in case of double stars of peculiar interest

Summary TheIAU Symposium No. 61 (Perth, 1973, “New Problems in Astrometry’) makes clear that radiosources will play an important role for astrometry in view of the linkage of reference systems. The purposes developed later were to link the various systems from the earth and the solar system to the most inertial possible one. Extragalactic radiosources are the most reliable objects but they are faint. So, intermediate objects are needed. Among them the radiostars, optical objects having radioemission at a certain level and for given frequencies have a fundamental and key position. Most of such radiostars are double or multiple ‘binaries’ as it can be seen from the list of reference stars issued by the Working Group of Commission 24, Working Group created in 1978. The last issue of the core list of radiostars was presented by Ch. de Vegt (Chairman of the WG) on the occasion of the last General Assembly of the IAU (November 1985). A recent study of the system α Scorpii (Antares) has shown that the data concerning the magnitude and the spectral type are not accurate enough, according to the accuracy obtained for the astrometric position (±0 _. ^s 003 for an astrolabe campaign in right ascension). There is also a need for better knowledge about the orbits. In the case of the astrolabe observations, if the distance between the components in <3″ the astrometric position concerns the photocenter and accurate physical properties are needed for comparison with the radio position. Better astrophysical properties are strongly needed for all radiostars to be used as references, during the time the astrometrists have to improve the accuracy of their measurements both in optical and radio fields. Presented by S. Débarbat.     

Search for Candidate Objects with the Sunyaev–Zeldovich Effect in the Radio Source Vicinities—galaxies: clusters: general

Based on the data from the Westerbork Northern Sky Survey performed at a frequency of 325 MHz in the range of right ascensions 0^h ≤ α < 2^h and declinations 29° < δ < 78° and using multi-frequency Planck maps, we selected candidate objects with the Sunyaev–Zeldovich effect. The list of the most probable candidates includes 381 sources. It is shown that the search for such objects can be accelerated by using a priori data on the negative level of fluctuations in the CMB map with removed low multipoles in the direction to radio sources.     

Studies of blue objects at high galactic latitudes

Continuing the survey for faint blue objects at high galactic latitudes, a field of 25 square degrees centered at the Coma Cluster of Galaxies has been examined on two-color plates taken with the 90-67 cm Schmidt telescope of Asiago. 487 objects have been identified. A selected list of those with the largest negative color index is given in Table I. Identification charts, notes and comments follow.     

Spectral observations of FBS blue stellar objects in the zone δ = + 35°

The next list of spectral data on blue stellar objects (BSOs) is presented. 58 FBS objects in a zone with a central declination δ = + 35° were observed with the 2.6-m telescope at the Byurakan Observatory during 1990–1991. In addition, 3 objects were observed (3 CCD spectra were obtained) with the BAO 2.6-m and OHP 1.93-m telescopes in 1997–2000 using modern instrumentation. 9 white dwarfs, 47 hot subdwarfs, and 2 HBB stars have been discovered. Spectra of the 10 most interesting objects are given. __________ Translated from Astrofizika, Vol. 51, No. 2, pp. 277–283 (May 2008).     

First Byurakan Spectral Sky Survey. Blue stellar objects. VIII. zone +65° ≤ δ ≤, + 69°

The eighth list of blue stellar objects in the second part of the First Byurakan Spectral Sky Survey (FBS) is presented. The objects are located in the zone +65° +69° and 5 ^h 15^m 18 ^h 05^m.The list contains data on 98 blue stellar objects detected, of which 73 are previously unknown. A preliminary classification of the objects is given. The exact coordinates of the centers and the limiting magnitudes of the plates for this zone have been determined using the charts of the Palomar Sky Survey.Translated from Astrofizika, Vol. 37, No. 2, pp. 197–206, April–June, 1994.This work has been performed with financial support of the ESO C&EE fund (A-02-043).