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A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
A study of gas-phase element abundances reported in the literature for17 different elements sampled over 243 sight lines in the local part ofour Galaxy reveals that the depletions into solid form (dust grains) areextremely well characterized by trends that employ only three kinds ofparameters. One is an index that describes the overall level ofdepletion applicable to the gas in any particular sight line, and theother two represent linear coefficients that describe how to derive eachelement's depletion from this sight-line parameter. The information fromthis study reveals the relative proportions of different elements thatare incorporated into dust at different stages of grain growth. Anextremely simple scheme is proposed for deriving the dust contents andmetallicities of absorption-line systems that are seen in the spectra ofdistant quasars or the optical afterglows of gamma-ray bursts. Contraryto presently accepted thinking, the elements sulfur and krypton appearto show measurable changes in their depletions as the general levels ofdepletions of other elements increase, although more data are needed toascertain whether or not these findings are truly compelling. Nitrogenappears to show no such increase. The incorporation of oxygen into solidform in the densest gas regions far exceeds the amounts that can takethe form of silicates or metallic oxides; this conclusion is based ondifferential measurements of depletion and thus is unaffected byuncertainties in the solar abundance reference scale.Based in large part on published observations from (1) the NASA/ESAHubble Space Telescope obtained at the Space Telescope ScienceInstitute, which is operated by the Association of Universities forResearch in Astronomy, Inc., under NASA contract NAS 5-26555, (2) theFar Ultraviolet Spectroscopic Explorer (FUSE) mission operated by JohnsHopkins University, supported by NASA contract NAS5-32985, and (3) TheCopernicus satellite, supported by NASA grant NAGW-77 to PrincetonUniversity.
| An Ultraviolet Search for Interstellar CS
High- and medium-resolution ultraviolet spectra from the Space TelescopeImaging Spectrograph (STIS) and the Goddard High Resolution Spectrograph(GHRS) were used to study the diatomic molecule CS through the C-X(0,0)band at 1401 Å. The band was modeled to verify profile shape. Therest wavelength of the C-X band is refined to a value of 1400.88 Åand a 3? lower limit is set on the oscillator strength at 0.14based on equivalent width upper limits of the A-X(0,0) CS Band at 2577Å. The strength of the 1401 Å band is compared to otherinterstellar parameters and implications for CS formation anddestruction are briefly discussed.
| A CO J = 1-0 survey of common optical/uv absorption sightlines
Context: Comparison of optical/uv absorption line data withhigh-resolution profiles of mm-wave CO emission provides complementaryinformation on the absorbing gas, as toward ? Oph. Over the pastthirty years a wealth of observations of CO and other molecules inoptical/uv absorption in diffuse clouds has accumulated for which nocomparable CO emission line data exist. Aims: To acquire mm-waveJ=1-0 CO emission line profiles toward a substantial sample ofcommonly-studied optical/uv absorption line targets and to compare withthe properties of the absorbing gas, especially the predicted emissionline strengths. Methods: Using the ARO 12 m telescope, weobserved mm-wavelength J=1-0 CO emission with spectral resolution R ?3× 106 and spatial resolution 1' toward a sample of 110lines of sight previously studied in optical/uv absorption lines of CO,H2, CH, etc. Results: Interstellar CO emission was detected along65 of the 110 lines of sight surveyed and there is a generalsuperabundance of CO emission given the distribution of galacticlatitudes in the survey sample. Much of the emission is optically thickor very intense and must emanate from dark clouds or warm dense gas nearHII regions. Conclusions: Judging from the statisticalsuperabundance of CO emission, seen also in the total line of sightreddening, the OB star optical/uv absorption line targets must bephysically associated with the large quantities of neutral gas whose COemission was detected, in which case they are probably influencing theabsorbing gas by heating and/or photoionizing it. This explains whyCO/H2 and 12CO/13CO ratios differ somewhat betweenuv and mm-wave absorption line studies. Because the lines of sight havebeen preselected to have AV ? 1 mag, relatively little ofthe associated material actually occults the targets, making itdifficult for CO emission line observations to isolate the foregroundgas contribution.Based on observations obtained with the ARO Kitt Peak 12 mtelescope.
| CN column densities and excitation temperatures
We analyse abundances and rotational temperatures of the interstellar CNmolecule. We have calculated the column densities and excitationtemperatures of the molecule along 73 lines of sight basing on ouroriginal measurements of the B 2?+ -X2?+ (0,0) vibrational band recorded in highsignal-to-noise ratio spectra and also for 88 directions based onmeasurements already available in literature. We compare the columndensities obtained from different bands of CN molecule available toground-based instruments. The obtained excitation temperatures in theanalysed directions show always an excess over the cosmic microwavebackground radiation (CMBR) temperature.
| The Variation of Magnesium Depletion with Line-of-Sight Conditions
In this paper we report on the gas-phase abundance of singly ionizedmagnesium (Mg II) in 44 lines of sight, using data from the Hubble SpaceTelescope (HST). We measure Mg II column densities by analyzing medium-and high-resolution archival Space Telescope Imaging Spectrograph (STIS)spectra of the 1240 Å doublet of Mg II. We find that Mg IIdepletion is correlated with many line-of-sight parameters [e.g.,f(H2), EB-V, EB-V/r, AV, andAV/r] in addition to the well-known correlation with. These parameters should be more directly relatedto dust content and thus have more physical significance with regard tothe depletion of elements such as magnesium. We examine the significanceof these additional correlations as compared to the known correlationbetween Mg II depletion and . While none of thecorrelations are better predictors of Mg II depletion than, some are statistically significant even assumingfixed . We discuss the ranges over which thesecorrelations are valid, their strength at fixed ,and physical interpretations.
| New Insights on Interstellar Gas-Phase Iron
In this paper we report on the gas-phase abundance of singly ionizediron (Fe II) for 51 lines of sight, using data from FUSE. Fe II columndensities are derived by measuring the equivalent widths of several UVabsorption lines and subsequently fitting those to a curve of growth.Our derivation of Fe II column densities and abundances creates thelargest sample of iron abundances in moderately to highly reddened linesof sight explored with FUSE, lines of sight that are on average morereddened than lines of sight in previous Copernicus studies. We presentthree major results. First, we observe the well-established correlationbetween iron depletion and and also find trendsbetween iron depletion and other line-of-sight parameters [e.g.,f(H2), EB-V, and AV], and we examinethe significance of these trends. Of note, a few of our lines of sightprobe larger densities than previously explored and we do not seesignificantly enhanced depletion effects. Second, we present twodetections of an extremely weak Fe II line at 1901.773 Å in thearchival STIS spectra of two lines of sight (HD 24534 and HD 93222). Wecompare these detections to the column densities derived through FUSEspectra and comment on the line's f-value and utility for future studiesof Fe II. Finally, we present strong anecdotal evidence that the Fe IIf-values derived empirically through FUSE data are more accurate thanprevious values that have been theoretically calculated, with theprobable exception of f1112.
| Hubble Space Telescope Survey of Interstellar 12CO/13CO in the Solar Neighborhood
We examine 20 diffuse and translucent Galactic sight lines and extractthe column densities of the 12CO and 13COisotopologues from their ultraviolet A-X absorption bands detected inarchival Space Telescope Imaging Spectrograph data withλ/Δλ>=46,000. Five more targets with GoddardHigh-Resolution Spectrograph data are added to the sample that more thandoubles the number of sight lines with published Hubble Space Telescopeobservations of 13CO. Most sight lines have12CO-to-13CO isotopic ratios that are notsignificantly different from the local value of 70 for12C/13C, which is based on millimeter-waveobservations of rotational lines in emission from CO and H2COinside dense molecular clouds, as well as on results from opticalmeasurements of CH+. Five of the 25 sight lines are found tobe fractionated toward lower 12C/13C values, whilethree sight lines in the sample are fractionated toward higher ratios,signaling the predominance of either isotopic charge exchange orselective photodissociation, respectively. There are no obvious trendsof the 12CO-to-13CO ratio with physical conditionssuch as gas temperature or density, yet 12CO/13COdoes vary in a complicated manner with the column density of either COisotopologue, owing to varying levels of competition between isotopiccharge exchange and selective photodissociation in the fractionation ofCO. Finally, rotational temperatures of H2 show that allsight lines with detected amounts of 13CO pass through gasthat is on average colder by 20 K than the gas without 13CO.This colder gas is also sampled by CN and C2 molecules, thelatter indicating gas kinetic temperatures of only 28 K, enough tofacilitate an efficient charge exchange reaction that lowers the valueof 12CO/13CO.
| The Projected Rotational Velocity Distribution of a Sample of OB stars from a Calibration Based on Synthetic He I Lines
We derive projected rotational velocities (v sin i) for a sample of 156Galactic OB star members of 35 clusters, H II regions, and associations.The He I lines at 4026, 4388, and 4471 Å were analyzed in order todefine a calibration of the synthetic He I full widths at half-maximum(FWHMs) versus stellar v sin i. A grid of synthetic spectra of He I lineprofiles was calculated in non-LTE using an extensive helium model atomand updated atomic data. The v sin i values for all stars were derivedusing the He I FWHM calibrations, but also, for those target stars withrelatively sharp lines, v sin i values were obtained from best-fitsynthetic spectra of up to 40 lines of C II, N II, O II, Al III, Mg II,Si III, and S III. This calibration is a useful and efficient tool forestimating the projected rotational velocities of O9-B5 main-sequencestars. The distribution of v sin i for an unbiased sample of early Bstars in the unbound association Cep OB2 is consistent with thedistribution reported elsewhere for other unbound associations.
| Hubble Space Telescope Measurements of Vacuum Ultraviolet Lines of Interstellar CH
Three interstellar absorption lines near 1370 Å seen toward ζOph have been assigned by Watson to Rydberg transitions in the G-X (or3d-X) band of CH. Our survey of a dozen diffuse interstellar lines ofsight shows that the three absorption lines are consistent with theknown column densities of CH, by deriving the following oscillatorstrengths: f(1368.74)=0.019+/-0.003, f(1369.13)=0.030+/-0.005, andf(1370.87)=0.009+/-0.001. We also determined intrinsic line widths thatcorrespond to decay rates of (1.5+/-0.6)×1011,(3.8+/-0.7)×1011, and (1.1+/-0.6)×1010s-1 for λλ1368, 1369, and 1370, respectively.These rates are significantly higher than those associated withradiative decays and, thus, are readily attributable to predissociationof the Rydberg state. A fourth interstellar line near 1271 Å hasbeen conjectured by Watson to be the strongest transition in the 4d-XRydberg band of CH. We detected this line along four sight lines and ourspectrum syntheses show that with f(1271.02)=0.007+/-0.002, it is alsoconsistent with the known column densities of CH. In addition, weconducted a search for the F-X band of CH near 1549 Å, andsuccessfully discovered two of its absorption features along four sightlines. The astronomical oscillator strengths derived for these featuresare f(1549.05)=0.021+/-0.006 and f(1549.62)=0.013+/-0.003. Finally, theX Per sight line provided us with an astronomical detection of anotherCH band via two D-X features near 1694 Å. Comparisons with resultsof available theoretical calculations for the four CH bands arepresented.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Cloud Structure and Physical Conditions in Star-forming Regions from Optical Observations. II. Analysis
To complement the optical absorption line survey of diffuse moleculargas in Paper I, we obtained and analyzed far-ultraviolet H2and CO data on lines of sight toward stars in Cep OB2 and Cep OB3.Possible correlations between column densities of different species forindividual velocity components, not total columns along a line of sightas in the past, were examined and were interpreted in terms of cloudstructure. The analysis reveals that there are two kinds of CH indiffuse molecular gas: CN-like CH and CH+-like CH. Evidenceis provided that CO is also associated with CN in diffuse molecularclouds. Different species are distributed according to gas density inthe diffuse molecular gas. Both calcium and potassium may be depletedonto grains in high-density gas, but with different dependencies onlocal gas density. Gas densities for components where CN was detectedwere inferred from a chemical model. Analysis of cloud structureindicates that our data are generally consistent with the large-scalestructure suggested by maps of CO millimeter-wave emission. On smallscales, the gas density is seen to vary by factors greater than 5.0 overscales of ~10,000 AU. The relationships between column densities of COand CH with that of H2 along a line of sight show similarslopes for the gas toward Cep OB2 and Cep OB3, but the CO/H2and CH/H2 ratios tend to differ, which we ascribe tovariation in average density along the line of sight.
| New Estimates of the Solar-Neighborhood Massive Star Birthrate and the Galactic Supernova Rate
The birthrate of stars of masses >=10 Msolar is estimatedfrom a sample of just over 400 O3-B2 dwarfs within 1.5 kpc of the Sunand the result extrapolated to estimate the Galactic supernova ratecontributed by such stars. The solar-neighborhood Galactic-plane massivestar birthrate is estimated at ~176 stars kpc-3Myr-1. On the basis of a model in which the Galactic stellardensity distribution comprises a ``disk+central hole'' like that of thedust infrared emission (as proposed by Drimmel and Spergel), theGalactic supernova rate is estimated at probably not less than ~1 normore than ~2 per century and the number of O3-B2 dwarfs within the solarcircle at ~200,000.
| Cloud Structure and Physical Conditions in Star-forming Regions from Optical Observations. I. Data and Component Structure
We present high-resolution optical spectra (at ~0.6-1.8 kms-1) of interstellar CN, CH, CH+, Ca I, K I, andCa II absorption toward 29 lines of sight in three star-forming regions,ρ Oph, Cep OB2, and Cep OB3. The observations and data reduction aredescribed. The agreement between earlier measurements of the totalequivalent widths and our results is quite good. However, our higherresolution spectra reveal complex structure and closely blendedcomponents in most lines of sight. The velocity component structure ofeach species is obtained by analyzing the spectra of the six species fora given sight line together. The tabulated column densities and Dopplerparameters of individual components are determined by using the methodof profile fitting. Total column densities along lines of sight arecomputed by summing results from profile fitting for individualcomponents and are compared with column densities from the apparentoptical depth method. A more detailed analysis of these data and theirimplications will be presented in a companion paper.
| Catalog of Galactic OB Stars
An all-sky catalog of Galactic OB stars has been created by extendingthe Case-Hamburg Galactic plane luminous-stars surveys to include 5500additional objects drawn from the literature. This work brings the totalnumber of known or reasonably suspected OB stars to over 16,000.Companion databases of UBVβ photometry and MK classifications forthese objects include nearly 30,000 and 20,000 entries, respectively.
| A HIPPARCOS Census of the Nearby OB Associations
A comprehensive census of the stellar content of the OB associationswithin 1 kpc from the Sun is presented, based on Hipparcos positions,proper motions, and parallaxes. It is a key part of a long-term projectto study the formation, structure, and evolution of nearby young stellargroups and related star-forming regions. OB associations are unbound``moving groups,'' which can be detected kinematically because of theirsmall internal velocity dispersion. The nearby associations have a largeextent on the sky, which traditionally has limited astrometricmembership determination to bright stars (V<~6 mag), with spectraltypes earlier than ~B5. The Hipparcos measurements allow a majorimprovement in this situation. Moving groups are identified in theHipparcos Catalog by combining de Bruijne's refurbished convergent pointmethod with the ``Spaghetti method'' of Hoogerwerf & Aguilar.Astrometric members are listed for 12 young stellar groups, out to adistance of ~650 pc. These are the three subgroups Upper Scorpius, UpperCentaurus Lupus, and Lower Centaurus Crux of Sco OB2, as well as VelOB2, Tr 10, Col 121, Per OB2, alpha Persei (Per OB3), Cas-Tau, Lac OB1,Cep OB2, and a new group in Cepheus, designated as Cep OB6. Theselection procedure corrects the list of previously known astrometricand photometric B- and A-type members in these groups and identifiesmany new members, including a significant number of F stars, as well asevolved stars, e.g., the Wolf-Rayet stars gamma^2 Vel (WR 11) in Vel OB2and EZ CMa (WR 6) in Col 121, and the classical Cepheid delta Cep in CepOB6. Membership probabilities are given for all selected stars. MonteCarlo simulations are used to estimate the expected number of interloperfield stars. In the nearest associations, notably in Sco OB2, thelater-type members include T Tauri objects and other stars in the finalpre-main-sequence phase. This provides a firm link between the classicalhigh-mass stellar content and ongoing low-mass star formation. Detailedstudies of these 12 groups, and their relation to the surroundinginterstellar medium, will be presented elsewhere. Astrometric evidencefor moving groups in the fields of R CrA, CMa OB1, Mon OB1, Ori OB1, CamOB1, Cep OB3, Cep OB4, Cyg OB4, Cyg OB7, and Sct OB2, is inconclusive.OB associations do exist in many of these regions, but they are eitherat distances beyond ~500 pc where the Hipparcos parallaxes are oflimited use, or they have unfavorable kinematics, so that the groupproper motion does not distinguish it from the field stars in theGalactic disk. The mean distances of the well-established groups aresystematically smaller than the pre-Hipparcos photometric estimates.While part of this may be caused by the improved membership lists, arecalibration of the upper main sequence in the Hertzsprung-Russelldiagram may be called for. The mean motions display a systematicpattern, which is discussed in relation to the Gould Belt. Six of the 12detected moving groups do not appear in the classical list of nearby OBassociations. This is sometimes caused by the absence of O stars, but inother cases a previously known open cluster turns out to be (part of) anextended OB association. The number of unbound young stellar groups inthe solar neighborhood may be significantly larger than thoughtpreviously.
| Origin and Evolution of the Cepheus Bubble
We have imaged a 10 deg x 10 deg region of the Cepheus bubble in the J =1-0 line of CO and the 21 cm line of atomic hydrogen. The CO emissiondefines a giant expanding shell 120 pc in diameter, which is similar tothat seen in the IRAS sky maps. We estimate the total gas mass in theregion to be ~4 x 10^5 M_ȯ. The total kinetic energy from theobserved spread of velocities of the molecular clouds is ~10^51 ergs. Wesuggest that the members of earlier generations of massive stars in NGC7160 are responsible for the origin of the Cepheus bubble. These starscreated an expanding compressed shell of gas that became gravitationallyunstable at an age of ~7 Myr. The members of the Cepheus OB2 associationcomprise the second, intermediate generation of stars in this regionthat formed as a consequence of this instability. The numerous colorselected IRAS point sources represent the third and youngest generationof stars in this region. Our observations suggest the great importanceof sequentially triggered star formation in the region of the Cepheusbubble.
| UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars
A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| A New Bright Eclipsing Variable in Cepheus
Not Available
| Galactic OB associations in the northern Milky Way Galaxy. I - Longitudes 55 deg to 150 deg
The literature on all OB associations was reviewed, and their IRAS pointsource content was studied, between galactic longitude 55 and 150 deg.Only one third of the 24 associations listed by Ruprecht et al. (1981)have been the subject of individual studies designed to identify thebrightest stars. Distances to all of these were recomputed using themethod of cluster fitting of the B main sequence stars, which makes itpoossible to reexamine the absolute magnitude calibration of the Ostars, as well as for the red supergiant candidate stars. Also examinedwas the composite HR diagram for these associations. Associations withthe best defined main sequences, which also tend to contain very youngclusters, referred to here as OB clusters, have extremely few evolved Band A or red supergiants. Associations with poorly defined mainsequences and few OB clusters have many more evolved stars. They alsoshow an effect in the upper HR diagram referred to as a ledge byFitzpatrick and Garmany (1990) in similar data for the Large MagellanicCloud. It is suggested that the differences in the associations are notjust observational selection effects but represent real differences inage and formation history.
| Catalog of O-B stars observed with Tokyo Meridian Circle
A catalog of the O-B stars, selected from 'Blaauw-Parenago' list andRubin's catalog, has been compiled on the FK4 system by the observationsmade with Gautier 8-inch Meridian Circle at the Tokyo AstronomicalObservatory during the period, 1971 to 1979. It contains 1059 stars andwas compiled for the future establishment of high precision propermotions of O-B stars.
| Spectrophotometric investigation of OB stars in the region of the association CEP OB2
The results are given of spectrophotometric investigation of 39 OB starsin the region of the association Cep OB2. The blue (4000-4800 A)absolute spectrophotometric gradients, the color excesses in the UBVsystem, and the distances of these stars have been determined. Analysisof the results suggests that the absorbing material is basicallyconcentrated within the association itself.
| H-beta photometry of northern intermediate galactic latitude early-type stars and galactic structure away from the plane
Photoelectric H-beta photometry is presented for 255 early-type stars atintermediate galactic latitudes. Absolute magnitudes and distances arederived for the more luminous stars. Those with visual magnitudes lessthan or equal to 2.5 and at distances of up to 1 kpc from the galacticplane may follow the spiral structure in the plane.
| On the origin of intermediate-latitude OB stars
An attempt is made to trace the origin of early-type stars observed atappreciable distances from the galactic plane. Because uncertainties inthe proper motions make space motions and hence dynamical lifetimesrather inaccurate, a theory of oscillations normal to the plane has beenused to compute radial velocities for 138 intermediate-latitude OBstars. These theoretical values are then compared with the observedradial velocities, and it is found that the low-velocity stars wereprobably ejected from the plane some time after formation, while thehigh-velocity stars were ejected very soon after formation. Velocitiesof ejection perpendicular to the plane are computed and show a narrowdistribution with a mean absolute value of 7 km/s together with a spreadof velocities from about 40 to over 200 km/s. The data are in reasonableagreement with a 'sling' effect and 'runaway' origin for the stars inthe sample.
| UBV photometry and MK spectral classification of northern early-type stars at intermediate galactic latitudes
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977MNRAS.180..691H&db_key=AST
| Helium abundance in atmospheres of stars appearing in OB associations and young clusters
An improved version of Liubimkov's (1974) method is used to determinethe relative helium abundance, N(He)/N(H), in the atmospheres of 80stars of spectral types O6.5 to B2 belonging to OB associations andyoung clusters. Specific results are presented for Mon OB1 and OB2, CepOB2 and OB3, Sco OB2, Lac OB1, Ori OB1, and Cas OB6. It is shown thatthe mean value of N(He)/N(H) increases with increasing stellar age andincreasing cluster or association size. A relative helium abundance of0.09 to 0.10 is found to be appropriate for stars that are severalmillion years old, and a relative abundance of 0.13 is obtained forstars older than 10 million years. It is noted that the latter value isalso characteristic of hot field stars.
| UBV photometry of 180 early-type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974PASP...86..795G&db_key=AST
| Some Spectroscopic Characteristics of the OB Stars: an Investigation of the Space Distribution of Certain OB Stars and the Reference Frame of the Classification
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJS...23..257W&db_key=AST
| Photoelectric photometry of early-type stars in a Milky Way field in Cepheus
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....2..251S&db_key=AST
| A Spectroscopic and Photometric Investigation of the Association Cepheus OB2
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968ApJ...154..923S&db_key=AST
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| Sað Açýklýk: | 21h45m42.37s |
| Yükselim: | +62°18'30.0" |
| Görünürdeki Parlaklýk: | 7.487 |
| Uzaklýk: | 1470.588 parsek |
| özdevim Sað Açýklýk: | -0.4 |
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