eta Car: the optical features at the 2003.5 low-excitation event
UBV and BVR photometry of eta Car during the 2003.5 low-excitationevent - the considered periastron passage of a binary - is presented.The light and colour curves show a number of features, which were alsoseen at previous periastron passages: a light maximum of long durationwith a superimposed flare-like event which is temporarily interrupted byan eclipse-like dip, and a steep decline in the U-B color index. The Rbrightness reached a minimum at the time of mid X-ray totality, probablyimplying that the Hα emission line reached a minimum. The sourceof the optical flare-like event is probably not the same as the onecausing the the X-ray radiation. It is tempting to consider the epoch ofthe R minimum and the mid- X ray totality - which roughly coincides withthe UBV minimum - as the central moment of the 2003.5 low-excitationevent.
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Searching for unknown open clusters in the Tycho-2 catalog
We present 11 new open cluster candidates found in a systematic searchfor unknown star clusters using the astrometric and photometric dataincluded in the Tycho 2 catalog. The possible existence of these stellaraggregates is supported by the analysis of proper motions,color-magnitude diagrams, stellar density distributions, and by thevisual inspection of the Digitized Sky Survey (DSS) plates. With thesetools we were able to determine mean absolute proper motions as well aspreliminary reddenings, distances and ages for the majority of thecandidates. We found that most of them are possibly nearby (closer than~ 600 pc) open clusters never studied before.Based on observations of the ESA Hipparcos satellite.Figures 1 and 2 are only available in electronic form athttp://www.edpsciences.org
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The Carina Spiral Feature: Strömgren-Hβ photometry approach. I. The photometric data-base
A data-base collating all uvbybeta photometry available at present forO-B9 stars brighter than 10th visual magnitude in the field of theCarina Spiral Feature is presented. The completeness and homogeneity ofthe data-base are discussed.Based on CDS data.Table 1 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/410/523
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New perceptions on the S Doradus phenomenon and the micro variations of five Luminous Blue Variables (LBVs)
We investigated the photometric histories of the LBVs HR Car in theGalaxy, R127, R110 and R71 in the LMC, and R40 in the SMC by collectingall available photometry. All these objects have been reasonably wellobserved over the last few decades and a number of "S Dor (SD) phases"(episodes of enhanced light) is well documented. Time-scales lie between1.4 and 25y. During the SD cycles two different types ofmicro-variations (amplitudes ~0.2') are present: one near the minima(time-scale from 2 to 6 weeks; colours generally blue in the maxima andred in the minima) and the other one near the maxima (time-scale ~100d;colours generally red in the maxima and blue in the minima). Halfway theascending and descending branches of the SD cycles the stars switchrather abruptly from one type to the other. We argue that the two typesof SD phases are probably caused by different instability mechanisms.Based, in part, on observations obtained at the European SouthernObservatory at La Silla, Chile.
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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.
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A pulsating star inside η Carinae. I. Light variations, 1992-1994.
We present and analyze two seasons of intense photometric monitoring inthe Stroemgren uvbyHβ system of η Carinae (October 1992-August1994). The luminous blue variable (LBV) in the core did not show much SDor activity, i.e. it was in a relatively quiescent stage. Thissituation was very favourable for studying its optical micro variations.It appears that the central LBV pulsates (presumably in a non-radialmode) like other massive evolved stars, the α Cyg variables. Thequasi-period is 58.56d. The linear ephemeris is: JD_max_ = 2448875.0+58.56 E. Support was found for the existence of the presumedperiodicity of 52.4d of the so-called "dimples", shallow dips in thelight curve which only last for a few days. The cause may be the eclipseof a small companion or of a hot spot in an accretion disk. The Hβindex became bluer by ~0.07mag during the last 11/2 years and shows anoscillation in anti-phase with the 58.56d pulsation, suggesting that theHII region(s) responsible for the hydrogen line emission has arelatively high luminosity. This is another reason to suppose that asecond luminous source, perhaps a luminous disk (with a hot spot), maybe present in the η Car system.
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Longterm Photometry of Variables at ESO - Part Two - the Second Data Catalogue 1986-1990
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&AS..102...79S&db_key=AST
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Long-term photometry of variables at ESO. I - The first data catalogue (1982-1986)
This paper presents the catalog of photometric data in the Stromgrensystem obtained during the first four years (October 1982 - September1986) of the Long-Term Photometry of Variables (LTPV) program at ESO.The data are available in computer-readable form.
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Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
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CCD measurements of visual binaries
CCD measurements of visual double stars were obtained with the ESO 1.5 mdanish reflector. All binaries observed are candidates for the HIPPARCOSInput Catalogue. More than 400 observations have been made in four clearnights. The accuracy obtained is comparable to the accuracy of thephotographic technique, but the observing and reduction times are oneorder of magnitude smaller.
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Instrumental effects and the Stroemgren photometric system
The extent to which the use of different photometers can affect resultson stellar color indices was investigated by simultaneously observing asample of widely different stars with several uvby photometric systemsavailable at the ESO, La Silla, Chile. In one instance, the ESO 50-cmtelescope and the four-channel photometer at the Danish 50-cm telescopewere used simultaneously. The reductions were performed separately oneach data set, using a linear color transformation procedure. Theresults agree with theoretical investigations which showed thatsubstantial errors can arise from the nonconformity of passbands. It isemphasized that it is necessary to use separate color transformationsfor various stellar types and classes and for different interstellarreddenings.
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A study of visual double stars with early type primaries. IV Astrophysical data
Astrophysical parameters (MK class, color excess, absolute magnitude,distance, effective temperature, mass, and age) are derived fromcalibrations of the uvby-beta indices for the members of 253 doublestars with O or B type primaries and faint secondaries. The photometricspectral classification is compared to the MK classes, and the agreementis very good. The derived data together with spectroscopic and JHKL dataare used for deciding which pairs are likely to be physical and whichare optical, and it is shown that 98 (34 percent) of the secondaries arelikely to be members of physical systems. For 90 percent of the physicalpairs the projected separation between the components is less than25,000 AU. A majority of the physical secondaries are late-type stars,and 50 percent of them are contracting towards the zero-agemain-sequence. Also presented are new uvby-beta data for 43 secondariesand a computer program for determining astrophysical parameters fromuvby-beta data.
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Erratum - Distant Blue Stars in the Southern Milky-Way
Not Available
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A study of visual double stars with early type primaries. II - Photometric results
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1983A&AS...51..161L&db_key=AST
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A study of visual double stars with early type primaries. I - Spectroscopic results
Attention is given to spectral peculiarities found in data on thespectral classes of 486 stars in 254 visual doublet or multiplet systemswith O or B type primaries, in order to isolate a group of very youngstars that may serve for the study of early stellar evolutioncharacteristics. It is noted that the material contains a substantialfraction of secondaries that are likely to be physical, and that severalof these may be in the premain-sequence phase of stellar evolution, orhave reached the zero-age main sequence.
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Erratum - Errors in the HD Identification in Spectral Survey of the Southern Milky way - Part Three
Not Available
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Equivalent widths and rotational velocities of southern early-type stars
Not Available
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Photoelectric measures of the hydrogen lines in early-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974MNRAS.169..171F&db_key=AST
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The OB stars in Carina-Centaurus
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969MNRAS.143..273F&db_key=AST
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Radial velocities of Southern B stars determined at the Radcliffe Observatory.
Not Available
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INHABITED SKY
