The galactic warp and rotations of the fundamental system

The proper motion in galactic latitude of O-B stars enables us to detect the kinematic behaviour of an optical counterpart of the large-scale warp of the HI gas layer in our Galaxy. A selected set of the proper motions of about 350 O-B stars within 3kpc from the sun (R₀=8.5kpc) is analyzed on the proper motion systems of N30, FK4, and FK5. A remarkable differece in the kinematic behaviour of the warp appears between the old systems (N30 and FK4) and FK5-system. On the old systems, the O-B stars in the belt 8.5kpcR<9.5kpc exhibit a systematic z-motion upward from the galactic plane forl180° and downward forl>180° with the mean proper motions of about ±0".4/century, respectively. On the other hand, the results on the FK5-system show no meaningful systematic z-motion, even though the O-B star layer exterior to the solar circle is inclined (3°) with respect to the galactic plane. These findings can neither be inferred from the model of the oblique material flow nor from the concepts of the precessional stellar rings and of the bending oscillation of a stellar disk. The remarkable difference in the kinematic behaviour of the warp, appearing between the old and new systems, is caused mainly by the conversion of the proper motions on the old systems into those on the J2000.0 frame. The conversion near the galactic plane is given by µ_b(FK4(J2000.0))–µ_b(FK4)–0.50 sinl/century. The implication of this relation is discussed in connection with the warping motion of stars detected here.     

Radial pulsation of less-massive yellow supergiants

The conclusions of the present paper broadly are: (a) The galactic concentration of doubles by comparing the distributions in galactic latitudes 0°<20° and >40° is nearly twice as large as the galactic concentration of stars in general. (b) The astrographic catalogues are not complete in the fainter magnitudes. (c) The large value of the ratioT:O _k (observed to optical number of pairs) from Kreiken's formula shows that almost all stars in the group 0<d5 and quite a few in the other two groups, viz., 5<d10 and 10<d15 might be shown true binaries. Consequently, Aitken's working definition of a true binary should be extended if it were to include all true binaries. (d) The doubles are probably stars of Population I. (e) The logarithm to the base 10 of the cumulative counts can be represented by an empirical relationA+B(m–1.5)+C(m–1.5)².Communication presented at the International Conference on Astrometric Binaries, held on 13–15 June, 1984, at the Remeis-Sternwarte Bamberg, Germany, to commemorate the 200th anniversary of the birth of Friedrich Wilhelm Bessel (1784–1846)     

On the weakness of diffuse galactic light off the Milky Way

Observations have been selected in Tenerife Zodiacal Light Data, which make it possible to separate the diffuse galactic light from other components. Far from the Milky Way (30°|b|60°) the diffuse galactic light shows a decreasing slope which cannot exceed –0.3S ₁₀ vis. per degree of galactic latitude, and is probably a very weak component of the total extraterrestrial light.     

Short period Miras and Galactic Structure

Red Giants on the Asymptotic Giant Branch typically are more luminous than M _K = -7 mag. Therefore, a new Two Micron Sky Survey which will go as faint as m _K = 10 mag will be able to observe most of these stars in the Milky Way. Such a complete census will enable us to develop a much better understanding of Galactic Structure. It will be important to separate the luminous red giants into their different subclasses because these subclasses trace different Galactic Populations. For example, Miras with periods less than 300 days can be used to study the thick disk while Miras with periods greater than 300 days belong to the thin disk.     

Study of the outer galactic structure for 288°≤l≤310°, −7°≤b≤2°

The structure of the outer part of the Galaxy is studied, based upon 21-cm line observations of Hi in the region 288°l310°, –7°b2°.In this longitude range the galactic plane is strongly bend toward negative latitudes.The principal outer structure is a spiral arm which has a pitch angle of 10° and is formed by several concentrations differing in shape and size. There exists also a secondary concentration which could be a split from the previous structure.Possible hypotheses about the origin of the later feature are discussed.     

Galactic4He and heavy elements enrichment by stellar nucleosynthesis

The contribution to the galactic abundance of He and heavy elements by stellar nucleosynthesis is calculated as a function of time, keeping account of present knowledge about stellar and galactic evolution. A model is used which distinguishes the phase of the contracting halo from the subsequent history of the disc. Various uncertainties involved both in stellar and in galactic evolutionary theory are discussed. The amount of⁴He produced by stars of different masses and ejected in interstellar medium is fairly well known from stellar theory, while we have assumed its primordial abundance as a free parameter, ranging from 0 up to 0.4. We find that stellar activity provides a significant contribution to the cosmic⁴He, though not sufficient to explain the observed abundance. The best agreement with observational data (Y 0.26 andY _now0.28) is obtained starting with a primordial abundanceY =(0.20–0.23), which is consisten with the Big-Bang theory predictions and with recent observational estimates. The contribution to the abundance of heavy elements depends on the last stellar stages and on the final explosion mechanism, which are only now beginning to be understood. Nevertheless, in the framework of present theories, we individuate a stellar evolutionary scheme reproducing the observedZ abundances for Populationi and Populationii stars, with the correctly estimated Y/Z value. In this scheme, only stars belonging to two narrow mass ranges (10m/m 15 andm/m 80) are allowed to eject metal-enriched matter, possibly with the solar (C+O)/(Si+Fe) ratio.     

Possible evidence for a massive black hole in a quasar with double redshift systems

With the aid of a simple black hole model of quasars we have found that the majority of the distinguishable emission lines in the spectrum of the quasar 1604+179 can be assigned to two redshift systems,z _r =3.712 andz _b =2.701. The appearance of double emission redshifts means that this quasar might be a massive black hole (of mass 10⁸ M M10¹¹ M ) with a ring-like emission line region (of radius 1 light-day r ₀1 light-year) in its accretion disk.     

Linearized limb-darkening coefficients for use in analysis of eclipsing binary light curves

Linear limb-darkening coefficientsu required in the analysis of eclipsing binary curves, are tabulated for a wide range of effective temperature (50 000° to 4000°), wavelength (0.2 2.2 ), and gravitiesg (2.0logg5.0). The computation is based on the comprehensive range of model atmospheres of Carbon and Gingerich (1969).The results are compared with the theoretical values of Hosokawa (1957), Kopal (1959) and Grygaret al. (1972), and examined in relation to empirically determined values ofu from analyses of eclipsing binary light curves. An improved agreement between theory and observation for the calculated limb-darkening coefficients of the present work is noted.     

The first byurakan Spectral Sky Survey. Blue stellar objects. X. The zone+73°≤σ≤+80°

We present the tenth list of blue stellar objects of the second part of the First Byurakan Spectral Sky Survey (FBS). The list contains 100 objects in the region+73°+80° and3 ^h 30 ^m 18 ^h 30 ^m encompassing an area of 355 square degrees. The objects have stellar V magnitude within the limits 12.0–18.5 and B-V colors between–0.77 and+0.37. Of these 100 objects, 80 were discovered for the first time. We give the equatorial coordinates, stellar V magnitude, color index CI, and preliminary classification of the objects on the basis of low-disperion prismatic spectra. For 29 objects we give approximate types, among which 4 are candidates for quasars, 2 for Seyfert galaxies, 1 for superassociation galaxy IC 381, 18 for white dwarfs, and 4 for cataclysmic variables.Translated fromAstrofizika, Vol. 38, No. 2, 1995.     

Optical Identifications of IRAS Point Sources. Galaxies. VII

A seventh list of objects from the BIG (Byurakan-IRAS galaxies) sample is given: 95 galaxies identified with 63 point sources from the IRAS Point Source Catalog. The identifications were based on the Digital Sky Survey (DSS), the First Byurakan Survey, blue and red maps from the Palomar Observatory Sky Survey, and infrared fluxes at 12, 25, 60, and 100 m in the region of +65° 69° and 14^h00^m 18^h05^m with an area of 96 deg². For the identified galaxies the optical coordinates, their departures from the IR coordinates, the stellar V magnitudes, morphological types, angular sizes, and position angles were determined. The objects have optical magnitudes in the range of 13 ^m .8-21 ^m .5 and angular sizes in the range of 4-38. Finder charts from the DSS are given for these objects.     

First Byurakan Spectral Sky Survey. Blue stellar objects. VII. Zone +61° ≤δ ≤, +65°

The seventh 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 + 61° + 65° and 5 ^h 30^m 18 ^h 40 ^m .The list contains data on 119 blue stellar objects detected, of which 73 are previously unknown. A preliminary classification of the objects is given. The limiting magnitude of the FBS plates are determined using the photometric calibration of the charts of the Palomar Sky Survey.Translated fromAstrofizika, Vol. 37, No. 1, pp. 43–55, January–March, 1994.     

Redshift cutoff and evolution of QSOs

In this paper I present a new evolution model of QSOs luminosity. The model is based on edges distribution of apparent magnitude-redshift of QSOs. After the quasars were formed, the luminosities were increasing until they attained their maximum value atz=2+a, where –0.1a0.6, then the luminosities were decreasing. If the QSOs originate from superconducting cosmic string of same initial massM _i 10¹² M , the formation epochs are different, most of the quasars start atz _cutoff5.6. The most luminous QSOs start at later epochz _cutoff5.15. The present sky survey echniques may give us the possibility to see the formation of QSOs at apparent magnitudem _V 22.5 by chance of 0.3%.     

Numerical experiments in the 3/1 andv 6 overlapping resonance region

Numerical experiments of fictitious small bodies with initial eccentricities e=0.1 have been performed in the overlapping region of the 3/1 mean motion resonance and of thev ₆ secular resonance 2.48a2.52AU for different values of the initial inclination 16°i20°. An analysis for thev ₆ secular resonance shows that the topology is different from the one found outside the overlapping region: the critical argument for thev ₆ resonance in the overlapping region rotates in opposite direction as compared to the purev ₆ region. In the 3/1 resonance region the secular resonancev ₅ is dominant, and some secondary secular resonances asv ₆ –v ₁₆ andv ₅ +v ₆ are present.     

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).     

On the centre-to-limb variation and latitude dependence of the asymmetry and wavelength shift of the solar line λ 5576

Low noise photoelectric measurements of the line profile of the g = 0 Fe line gl 5576.097 combined with determinations of the wavelength shift of its centre calibrated by use of an I ₂ absorption tube are reported. Measurements taken at various limb distances (1.0 cos 0.2) and along 4 different diameters of the Sun are used to investigate the behaviour of the line asymmetry (C-shape) and wavelength shift of the line centre as functions of cos and of latitude and to search for possible pole-equator differences.An accuracy of approx. 0.8 mÅ r.m.s. is achieved for the determination of the centre of the solar line relative to the iodine lines and of 0.3 mÅ to 1 mÅ r.m.s. for the relative variations of the C-shape. The analysis shows a significant difference between the limb-effect curves along polar and equatorial diameters for cos 0.4 and changes of the C-shape for 0.9 cos 0.6 with a rather strong indication of a latitude dependence of the C-shape. This latitude dependence may account for the so-called ears observed by Howard et al. (1980) who used the well-known Doppler compensator method which integrates the line asymmetry from the line wings to the core.Mitteilungen aus dem Kiepenheuer-Institut Nr. 207.     

NSV 01450: a New Bright Classical Cepheid in the Milky Way Field

Photometric data extracted from more than 5000 CCD observations of theMilky Way field star NSV 01450, with galactic co-ordinates l =145^°.9and b=4^° .9, show that this object is a bright classical Cepheid witha period of 12.639 ± 0.020 days and an average V magnitude of 11.045± 0.016. The computed colour excess is E(B-V)= 0.553± 0.056, yielding a distance modulus m _V -M_V of 15.537 ± 0.212.In addition, it was found that the star GSC 3730_0797 in the field ofNSV 01450 is also variable.     

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.     

Optical Identifications of IRAS Point Sources. Galaxies. VI

A sixth list of objects from the BIG (Byurakan—IRAS galaxies) sample is given: 87 galaxies identified with 60 point sources from the IRAS Point Source Catalog. The identifications were based on the Digital Sky Survey (DSS), the First Byurakan Survey, blue and red maps from the Palomar Observatory Sky Survey, and infrared fluxes at 12, 25, 60, and 100 µm in the region of +65° +69° and 9^h15^m 14^h00^m with an area of 111 deg². We determined the optical coordinates of the identified galaxies, their departures from the IR coordinates, and their V magnitudes, morphological types, angular sizes, and position angles. The objects have optical magnitudes in the range of 12 ^m .5-21 ^m .5 and angular sizes in the range of 2-29. Finder charts from the DSS are given for these objects.     

An attempt to identify low l - low n solar acoustic modes

The low l solar acoustic spectrum has been measured with great accuracy (v/v 10^–4), for intermediate radial order modes, 11 n 34 (Jiménez et al., 1986; Grec, Fossat, and Pomerantz, 1983; Pallé et al., 1986). The measurement of the frequencies of modes of lower n, up to the fundamental one, are very important as they depart from asymptotic behaviour and, therefore, put more severe constraints on solar models. However, their amplitudes are very low (under 2 cm s^–1) and when compared to the solar velocity background noise (Jiménez et al., 1986), a S/N 1 is obtained. Taking advantage of the fact that lifetimes seem to be higher at lower frequencies (lower n values) (Jefferies et al., 1988; Elsworth et al., 1990), very long Doppler velocity measurements, obtained at Teide Observatory, have been used to increase S/N, therefore, providing the possibility to detect such modes. The frequencies observed are compared to those predicted by a solar model (Christensen-Dalsgaard, Däppen, and Lebreton, 1988), using the best equation of state yet computed (Mihalas, Däppen, and Hummer, 1988).     

The photometric solution of cc com by use of the

The contact binary system CC Com (=12^h09^m33^s.8, =+22°4339, (1950);V _max=11.31, (B-V)_max=1.24) is a W UMa-type system with the shortest known period. The photometric solution of CC Com is presented using the Wilson and Devinney method. The results show that the CC Com belongs to the late-type eclipsing binary with the spectral type K5V and K6V, low temperatureT ₁=4300 K,T ₂=4265 K, the mass ratioq=0.5873±0.0021, and the inclinationi=87°.719±1°.44. The best regions of the gravity darkening exponents , the bolomotric albedov, and the limb-darkening coefficients are tested. It is found that 0.1250.065, 0.1v0.5, =0.5 are better regions for CC Com. The third body ofl ₃ is not found to be significant. The results are combined with the spectroscopic results of Rucinski to provide an estimate of the absolute parameters.