The Abundance of Interstellar Fluorine and Its Implications
We report results from a survey of neutral fluorine (F I) in theinterstellar medium. Data from FUSE were used to analyze 26 lines ofsight lying in both the galactic disk and halo, including lines toWolf-Rayet stars and through known supernova remnants. The equivalentwidths of the fluorine resonance lines at 951.871 and 954.827 Åwere measured or assigned upper limits and combined with a nitrogencurve of growth to obtain F I column densities. These column densitieswere then used to calculate fluorine depletions. Comparisons are made tothe previous study of F I by Federman and coworkers and implications forF I formation and depletion are discussed.
|
Supernova remnant S 147 and its associated neutron star(s)
The supernova remnant S 147 harbors the pulsar PSRJ 0538+2817 whose characteristic age is more than an order ofmagnitude greater than the kinematic age of the system (inferred fromthe angular offset of the pulsar from the geometric center of thesupernova remnant and the pulsar proper motion). To reconcile thisdiscrepancy we propose that PSR J 0538+2817 could be the stellarremnant of the first supernova explosion in a massive binary system andtherefore could be as old as its characteristic age. Our proposalimplies that S 147 is the diffuse remnant of the second supernovaexplosion (that disrupted the binary system) and that a much youngersecond neutron star (not necessarily manifesting itself as a radiopulsar) should be associated with S 147. We use the existingobservational data on the system to suggest that the progenitor of thesupernova that formed S 147 was a Wolf-Rayet star (so that thesupernova explosion occurred within a wind bubble surrounded by amassive shell) and to constrain the parameters of the binary system. Wealso restrict the magnitude and direction of the kick velocity receivedby the young neutron star at birth and find that the kick vector shouldnot strongly deviate from the orbital plane of the binary system.
|
New beta Cephei and SPB Stars Discovered in Hipparcos Photometry
We discuss 34 stars for which we detected new frequencies in HipparcosHp magnitudes. 13 of these stars are variables discovered in this paper.For 20 stars, we derive log T_eff and log g from Stromgren or Genevaphotometry.We classify one new beta Cep star, HIP 88352, two new beta Cep suspects,HIP 54753 and 88123, four new SPBs, HIP 1030, 39206, 46192 and 111147,and two SPB suspects, HIP 75787 and 98778. We find the last star to betriply-periodic and we show that the frequencies detected in Hpmagnitudes are present in the photoelectric observations of Hill etal(1976).Finally, we discover the hottest variable of the SPB type, namely, HIP1030.
|
A photometric pilot study on Sonneberg archival patrol plates. How many ``constant'' stars are in fact long-term variables?
The light curves of 216 arbitrarly chosen field stars and of 23 knownvariables in the Aur/Tau/Ori region were derived (7.8 m ≤ B ≤12.2 m) from scanned, blue-sensitive archival patrol plates, covering atotal of 34 years (1961-1995). We achieved a photometric accuracy of0.07 ... 0.12 mag in spite of rather unfavourable locations of moststars near the plate borders. 17 field stars turned out to be variables,most of them with time scales of 1000-8000 days in the form of slowwaves with amplitudes between 0.1 and 0.3 mag, i.e. below the thresholdof traditional variable searches on photographic plates. About 50% ofthese new long-term variables exhibit drifts indicating periodic orerratic variability at much longer time scales than covered here. Forthe 23 known variables we achieved improvements in their periods andamplitudes and detected long-term variations (drifts, waves) in about50% of them. The above fraction of low-amplitude long-term variablesamong field stars implies that a total of about 45 000 new variablesshould be detectable in the Sonneberg patrol plate archive. They willrepresent a new, hitherto not investigated population of variable starswith a possibly significant impact on our understanding of the stellarinterior and evolution.Tables 2 and 3 are only available in electronic form athttp://www.edpsciences.org
|
Intermediate-velocity gas observed towards the Shajn 147 SNR
We present high-resolution spectra (R 3 km s-1) of theinterstellar Na I and Ca II interstellar absorption lines observedtowards 3 early-type stars with distances of 360 to 1380 pc along theline-of-sight towards the 800 pc distant Shajn 147 (S147) SupernovaRemnant (SNR). These data are supplemented with far-UV (912-1180Å) aborption spectra of HD 36665 andHD 37318 recorded with the NASA Far UltravioletSpectroscopic Explorer (FUSE) satellite. The observations revealintermediate-velocity (IV) absorption features at Vhelio =+92 km s-1 towards HD 37318 and atVhelio = -65 and -52 km s-1 towards HD36665, in addition to several other gas cloud components withlower velocity. These IV components can be associated with the expansionof the SNR that has disrupted the surrounding interstellar gas. The IVcomponent at V = +92 km s-1 seen towards HD37318 was detected only in the far-UV lines of Fe II and N II,suggesting that it is composed mainly of warm and ionized gas. The twoIV components observed towards HD 36665 were detectedin Na I, Ca II, N I, N II, O I and Fe II, indicating that it is composedof both neutral and ionized gas shells. Highly ionized gas was detectedin the O VIλ 1032 Å absorption line at V +40 kms-1 towards both stars. This hot and highly ionized gascomponent is characterized by a columnn density ratio of N(C IV)/N(O VI)< 0.27, which is consistent with that predicted by current models ofevolved SNRs. However, we cannot preclude its origin in the interstellarmedium in line-of-sight to S147. Column-density ratios of [Mg/Fe],[Al/Si],[Si/Fe], [N/Fe], [O/Fe] and [Na/Ca] have been derived for the IVgas components detected towards S147. Similar ratios have also beenderived for fast-moving gas observed towards two other SNRs in order togain some insight into the behavior of element abundances in thedisturbed interstellar gas associated with these regions. In all casesexcept for Na and Ca, these elements appear to be present withnear-solar abundance ratios.
|
A Search for High-Velocity Be Stars
We present an analysis of the kinematics of Be stars based uponHipparcos proper motions and published radial velocities. We findapproximately 23 of the 344 stars in our sample have peculiar spacemotions greater than 40 km s-1 and up to 102 kms-1. We argue that these high-velocity stars are the resultof either a supernova that disrupted a binary or ejection by closeencounters of binaries in young clusters. Be stars spun up by binarymass transfer will appear as high-velocity objects if there wassignificant mass loss during the supernova explosion of the initiallymore massive star, but the generally moderate peculiar velocities of BeX-ray binaries indicate that the progenitors lose most of their massprior to the supernova (in accordance with model predictions). Binaryformation models for Be stars predict that most systems bypass thesupernova stage (and do not receive runaway velocities) to createultimately Be+white dwarf binaries. The fraction of Be stars spun up bybinary mass transfer remains unknown, since the post-mass transfercompanions are difficult to detect.
|
The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
|
Catalogue of H-alpha emission stars in the Northern Milky Way
The ``Catalogue of Stars in the Northern Milky Way Having H-alpha inEmission" appears in Abhandlungen aus der Hamburger Sternwarte, Band XIin the year 1997. It contains 4174 stars, range {32degr <= l() II< 214degr , -10degr < b() II < +10degr } having the Hαline in emission. HBH stars and stars of further 99 lists taken from theliterature till the end of 1994 were included in the catalogue. We givethe cross-identification of stars from all lists used. The catalogue isalso available in the Centre de Données, Strasbourg ftp130.79.128.5 or http://cdsweb.u-strasbg.fr and at the HamburgObservatory via internet.
|
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.
|
Catalogue of stars in the northern Milky Way having H-alpha in emission
Not Available
|
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.
|
Chemical transitions for interstellar C2 and CN in cloud envelopes
Observations were made of absorption from CH, C2, and CN towardmoderately reddened stars in Sco, OB2, Ceo OB3, and Taurus/Auriga. Forthese directions, most of the reddening is associated with a singlecloud complex, for example, the rho Ophiuchus molecular cloud, and as aresult, the observations probe moderately dense material. When combinedwith avaliable data for nearby directions, the survey provides the basisfor a comprehensive analysis of the chemistry for these species. Thechemical transitions affecting C2 and CN in cloud envelopes wereanalyzed. The depth into a cloud at which a transition takes place wascharacterized by tauuv, the grain optical depth at 1000 A.One transition at tauuv approx. = 2, which arises from, theconversion of C(+) into CO, affects the chemistries for both moleculesbecause of the key role this ion plays. A second one involvingproduction terms in the CN chemistry occurs at tauuv ofapprox. = 3; neutral reactions which C2 and CH is more important atlarger values for tauuv. The transition fromphotodissociation to chemical destruction takes place attauuv approx. = 4.5 for C2 and CN. The observational data forstars in Sco OB2, Cep OB3, and Taurus/Auriga were studied with chemicalrate equations containing the most important production and destructionmechanisms. Because the sample of stars in Sco OB2 includes sight lineswith Av ranging from 1-4 mag, sight lines dominated byphotochemistry could be analyzed separately from those controlled bygas-phase destruction. The analysis yielded values for two poorly knownrate constants for reactions involved in the production of CN; thereactions are C2 + N yields CN + C and C(+) + NH yields all products.The other directions were analyzed with the inferred values. Thepredicted column densities for C2 and CN agree with the observed valuesto better than 50%, and in most instances 20%. When combining theestimates for density and temperature derived from chemical modeling andmolecular excitation for a specific cloud, such as the rho Ophiuchusmolecular cloud, the portion of the cloud envelope probed by C2 and CNabsorption was found to be in pressure equilibrium.
|
High-velocity interstellar gas toward HD 169454
The interstellar spectrum of HD 169454 reveals Na D and Ca K absorptionat about + 100 km/s. Measurements made at high resolution resolve 4narrow (about 2-3 km/s) features whose N(Ca II)/N(Na I) ratios aresmall. This high-velocity gas is, therefore, unique in that it resembleslocal quiescent gas, not shocked gas. Redshifted gas is also seen inmoderate-resolution spectra of faint stars lying in the same portion ofthe sky as HD 169454. The resulting picture is one in which a supernovaexplosion or stellar winds within the Sct OB3 association at a distanceof about 1.5 kpc is pushing quiescent gas away from the sun. The gas isseen only in stars estimated to be at most 3 kpc, but greater than 2kpc, away. If HD 169454 is at this greater distance, its absolutemagnitude would be about -9, making it the second most luminous B starin the Galaxy.
|
Spectral reclassification of some Be stars using Delta-Q method
The way in which the new defined value Delta-Q can play a role in thespectral reclassification of Be stars is shown by means of aninvestigation of 56 Be stars. A general survey carried out in order toobtain spectral subclasses or U, B, V values for these stars ispresented. The suggested Delta-Q method was found to be very helpful inchoosing the correct spectral subclass from among many subclassesassigned for the same star, and hence, the reclassification for thisstar.
|
55 emission stars discovered during observations of the Galactic anticenter at Abastumani
Not Available
|
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.
|
Further ultraviolet observations of interstellar gas associated with the supernova remnant S 147
UV observations by the IUE were employed to study the supernova remnant(SNR) gas from S 147 by viewing the star HD 37318. Spectra of HD 37318were examined in the 1150-2000 A and 1900-3200 A UV ranges. Comparisonsof the Fe II lines of HD 37318 with previous data on the same line fromHD 36665, behind the same SNR, indicated that the redshifted, highvelocity component of the line observed was part of the SNR gas.Furthermore, the high density electrons detected in the region of thegas in front of HD 37318 suggests that the area is filled with a shockedinterstellar cloud which is not entirely recombined. Depletion of heavyelements in the high velocity gas is indicative of a return to a gasphase through a sputtering process in the shock front, with the heavyelements existing as grains which are not destroyed by the 80 km/sechigh velocity gas.
|
High-velocity gas in supernova remnants. II. Shajn 147.
Abstract image available at:http://adsabs.harvard.edu/abs/1973ApJ...181..799S
|
Far-Ultraviolet Interstellar Absorption in Orion and Monoceros
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJ...166..543W&db_key=AST
|
Be stars and galactic rotation.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968AJ.....73..338C&db_key=AST
|
Spectral Classifications of 239 Early-Type Stars
Not Available
|
Spectroscopic absolute magnitudes of 571 B stars.
Not Available
|
Luminous Stars in the Northern Milky Way
Not Available
|
Troisième catalogue de l'Observatoire de Besançon comprenant 764 étoiles réduites à 1950, 0 sans mouvement propre et 326 étoiles FK3 pour l'époque moyenne d'observation
Not Available
|
Die galaktischen Emissions-B-Sterne : (Spectralklassifikation, Photometrie, Entwicklung und Verteilung in der Milchstraszenebene)
Not Available
|
A Spectroscopic and Photometric Study of the be Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1958ApJ...128..207M&db_key=AST
|
Gigantes azules EN las longitudes galacticas de 103 degres a 180 degres.
Not Available
|
Supplement to the Mount Wilson Catalogue and Bibliography of Stars of Classes B and a whose Spectra have Bright Hydrogen Lines.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1943ApJ....98..153M&db_key=AST
|
INHABITED SKY
