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IRS Spectra of Solar-Type Stars: A Search for Asteroid Belt Analogs
We report the results of a spectroscopic search for debris diskssurrounding 41 nearby solar-type stars, including eight planet-bearingstars, using the Infrared Spectrometer (IRS) on the Spitzer SpaceTelescope. With the accurate relative photometry of the IRS between 7and 34 μm we are able to look for excesses as small as ~2% ofphotospheric levels, with particular sensitivity to weak spectralfeatures. For stars with no excess, the 3 σ upper limit in a bandat 30-34 μm corresponds to ~75 times the brightness of our zodiacaldust cloud. Comparable limits at 8.5-13 μm correspond to ~1400 timesthe brightness of our zodiacal dust cloud. These limits correspond tomaterial located within the <1 to ~5 AU region that, in our solarsystem, originates predominantly from debris associated with theasteroid belt. We find excess emission longward of ~25 μm from fivestars, of which four also show excess emission at 70 μm. Thisemitting dust must be located in a region starting around 5-10 AU. Onestar has 70 μm emission but no IRS excess. In this case, the emittingregion must begin outside 10 AU; this star has a known radial velocityplanet. Only two stars of the five show emission shortward of 25 μm,where spectral features reveal the presence of a population of small,hot dust grains emitting in the 7-20 μm band. One of these stars, HD72905, is quite young (300 Myr), while the other, HD 69830, is olderthan 2 Gyr. The data presented here strengthen the results of previousstudies to show that excesses at 25 μm and shorter are rare: only 1out of 40 stars older than 1 Gyr or ~2.5% shows an excess. Asteroidbelts 10-30 times more massive than our own appear are rare amongmature, solar-type stars.
| Frequency of Debris Disks around Solar-Type Stars: First Results from a Spitzer MIPS Survey
We have searched for infrared excesses around a well-defined sample of69 FGK main-sequence field stars. These stars were selected withoutregard to their age, metallicity, or any previous detection of IRexcess; they have a median age of ~4 Gyr. We have detected 70 μmexcesses around seven stars at the 3 σ confidence level. Thisextra emission is produced by cool material (<100 K) located beyond10 AU, well outside the ``habitable zones'' of these systems andconsistent with the presence of Kuiper Belt analogs with ~100 times moreemitting surface area than in our own planetary system. Only one star,HD 69830, shows excess emission at 24 μm, corresponding to dust withtemperatures >~300 K located inside of 1 AU. While debris disks withLdust/L*>=10-3 are rare around oldFGK stars, we find that the disk frequency increases from 2%+/-2% forLdust/L*>=10-4 to 12%+/-5% forLdust/L*>=10-5. This trend in thedisk luminosity distribution is consistent with the estimated dust inour solar system being within an order of magnitude greater or less thanthe typical level around similar nearby stars. Although there is nocorrelation of IR excess with metallicity or spectral type, there is aweak correlation with stellar age, with stars younger than a gigayearmore likely to have excess emission.
| A search for debris discs around stars with giant planets
Eight nearby stars with known giant planets have been searched forthermal emission in the submillimetre arising from dust debris. The nullresults imply quantities of dust typically less than 0.02 Earth massesper star. Conversely, literature data for 20 Sun-like stars with debrisdiscs show that <= 5 per cent have gas giants inside a fewastronomical units - but the dust distribution suggests that nearly allhave more distant planets. The lack of overlap in these systems - i.e.few stars possess both inner planets and a disc - indicates that thesephenomena either are not connected or are mutually exclusive. Comparisonwith an evolutionary model shows that debris masses are predicted to below by the stellar ages of 2-8 Gyr (unless the colliding parent bodiesare quite distant, located beyond 100-200 au), but it remains to beexplained why stars that do have debris should preferentially only havedistant planets. A simple idea is proposed that could produce theselargely different systems, invoking a difference in the primordial discmass. Large masses promote fast gas giant growth and inwards migration,whereas small masses imply slow evolution, low-mass gas giants andoutwards migration that increases the collision rate of Kuiper Belt-likeobjects. This explanation neglects other sources of diversity betweendiscs (such as density and planetesimal composition and orbits), but itdoes have the merit of matching the observational results.
| Chemical enrichment and star formation in the Milky Way disk. III. Chemodynamical constraints
In this paper, we investigate some chemokinematical properties of theMilky Way disk, by using a sample composed by 424 late-type dwarfs. Weshow that the velocity dispersion of a stellar group correlates with theage of this group, according to a law proportional to t0.26,where t is the age of the stellar group. The temporal evolution of thevertex deviation is considered in detail. It is shown that the vertexdeviation does not seem to depend strongly on the age of the stellargroup. Previous studies in the literature seem to not have found it dueto the use of statistical ages for stellar groups, rather thanindividual ages. The possibility to use the orbital parameters of a starto derive information about its birthplace is investigated, and we showthat the mean galactocentric radius is likely to be the most reliablestellar birthplace indicator. However, this information cannot bepresently used to derive radial evolutionary constraints, due to anintrinsic bias present in all samples constructed from nearby stars. Anextensive discussion of the secular and stochastic heating mechanismscommonly invoked to explain the age-velocity dispersion relation ispresented. We suggest that the age-velocity dispersion relation couldreflect the gradual decrease in the turbulent velocity dispersion fromwhich disk stars form, a suggestion originally made by Tinsley &Larson (\cite{tinsley}, ApJ, 221, 554) and supported by several morerecent disk evolution calculations. A test to distinguish between thetwo types of models using high-redshift galaxies is proposed.Full Table 1 is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/423/517
| The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of 14 000 F and G dwarfs
We present and discuss new determinations of metallicity, rotation, age,kinematics, and Galactic orbits for a complete, magnitude-limited, andkinematically unbiased sample of 16 682 nearby F and G dwarf stars. Our63 000 new, accurate radial-velocity observations for nearly 13 500stars allow identification of most of the binary stars in the sampleand, together with published uvbyβ photometry, Hipparcosparallaxes, Tycho-2 proper motions, and a few earlier radial velocities,complete the kinematic information for 14 139 stars. These high-qualityvelocity data are supplemented by effective temperatures andmetallicities newly derived from recent and/or revised calibrations. Theremaining stars either lack Hipparcos data or have fast rotation. Amajor effort has been devoted to the determination of new isochrone agesfor all stars for which this is possible. Particular attention has beengiven to a realistic treatment of statistical biases and errorestimates, as standard techniques tend to underestimate these effectsand introduce spurious features in the age distributions. Our ages agreewell with those by Edvardsson et al. (\cite{edv93}), despite severalastrophysical and computational improvements since then. We demonstrate,however, how strong observational and theoretical biases cause thedistribution of the observed ages to be very different from that of thetrue age distribution of the sample. Among the many basic relations ofthe Galactic disk that can be reinvestigated from the data presentedhere, we revisit the metallicity distribution of the G dwarfs and theage-metallicity, age-velocity, and metallicity-velocity relations of theSolar neighbourhood. Our first results confirm the lack of metal-poor Gdwarfs relative to closed-box model predictions (the ``G dwarfproblem''), the existence of radial metallicity gradients in the disk,the small change in mean metallicity of the thin disk since itsformation and the substantial scatter in metallicity at all ages, andthe continuing kinematic heating of the thin disk with an efficiencyconsistent with that expected for a combination of spiral arms and giantmolecular clouds. Distinct features in the distribution of the Vcomponent of the space motion are extended in age and metallicity,corresponding to the effects of stochastic spiral waves rather thanclassical moving groups, and may complicate the identification ofthick-disk stars from kinematic criteria. More advanced analyses of thisrich material will require careful simulations of the selection criteriafor the sample and the distribution of observational errors.Based on observations made with the Danish 1.5-m telescope at ESO, LaSilla, Chile, and with the Swiss 1-m telescope at Observatoire deHaute-Provence, France.Complete Tables 1 and 2 are only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/989
| New spectroscopic binaries among nearby stars
In the course of surveying a large number of nearby (~50 pc or less)stars for indicators of youth, we have discovered a number of hithertounknown spectroscopic binaries. Here we present a list of these newbinaries with pertinent data. Two of these (HD 143705 and HD 89959) havebeen observed six times each, and their respective radial velocitycurves are discussed.Based on observations collected at the European Southern Observatory,Chile (ESO No. 62.I-0650, 66.D-0159(A), 67.D-0236(A)).
| Rotation and differential rotation in field F- and G-type stars
We present a detailed study of rotation and differential rotationanalyzing high resolution high S/N spectra of 142 F-, G- and earlyK-type field stars. Using Least Squares Deconvolution we obtainbroadening profiles for our sample stars and use the Fourier transformmethod to determine projected rotational velocities v sin i.Distributions of rotational velocities and periods are studied in theHR-diagram. For a subsample of 32 stars of spectral type F0-G0 we derivethe amount of differential rotation in terms of alpha = (Omega_Equator- Omega_Pole )/Omega_Equator . We find evidence for differentialrotation in ten of the 32 stars. Differential rotation seems to be morecommon in slower rotators, but deviations from rigid rotation are alsofound in some fast rotators. We search for correlations betweendifferential rotation and parameters relevant for stellar activity andshow indications against strong differential rotation in very activestars. We derive values of Delta P and Delta Omega , which support aperiod dependence of differential rotation. Derived lap times 2pi /DeltaOmega are of the order of 20 d and contradict the assumption thatconstant lap times of the order of the solar one ( ~ 130 d) are therule in stars that are thought to harbour magnetic dynamos.Based on observations collected at the European Southern Observatory, LaSilla.Tables 3 and A1 are only available at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.125.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/398/647
| HIPPARCOS age-metallicity relation of the solar neighbourhood disc stars
We derive age-metallicity relations (AMRs) and orbital parameters forthe 1658 solar neighbourhood stars to which accurate distances aremeasured by the HIPPARCOS satellite. The sample stars comprise 1382 thindisc stars, 229 thick disc stars, and 47 halo stars according to theirorbital parameters. We find a considerable scatter for thin disc AMRalong the one-zone Galactic chemical evolution (GCE) model. Orbits andmetallicities of thin disc stars show now clear relation each other. Thescatter along the AMR exists even if the stars with the same orbits areselected. We examine simple extension of one-zone GCE models whichaccount for inhomogeneity in the effective yield and inhomogeneous starformation rate in the Galaxy. Both extensions of the one-zone GCE modelcannot account for the scatter in age - [Fe/H] - [Ca/Fe] relationsimultaneously. We conclude, therefore, that the scatter along the thindisc AMR is an essential feature in the formation and evolution of theGalaxy. The AMR for thick disc stars shows that the star formationterminated 8 Gyr ago in the thick disc. As already reported by Grattonet al. (\cite{Gratton_et.al.2000}) and Prochaska et al.(\cite{Prochaska_et.al.2000}), thick disc stars are more Ca-rich thanthin disc stars with the same [Fe/H]. We find that thick disc stars showa vertical abundance gradient. These three facts, the AMR, verticalgradient, and [Ca/Fe]-[Fe/H] relation, support monolithic collapseand/or accretion of satellite dwarf galaxies as likely thick discformation scenarios. Tables 2 and 3 are only available in electronicform at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)or via http:/ /cdsweb.u-strasbg.fr/ cgi-bin/qcat?J/ A+A/394/927
| Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
| Optical, infrared and millimetre-wave properties of Vega-like systems - IV. Observations of a new sample of candidate Vega-like sources
Photometric observations at optical and near-infrared wavelengths arepresented for members of a new sample of candidate Vega-like systems, ormain sequence stars with excess infrared emission due to circumstellardust. The observations are combined with IRAS fluxes to define thespectral energy distributions of the sources. Most of the sources showonly photospheric emission at near-IR wavelengths, indicating a lack ofhot (~1000K) dust. Mid-infrared spectra are presented for four sourcesfrom the sample. One of them, HD 150193, shows strong silicate emission,while another, HD 176363, was not detected. The spectra of two starsfrom our previous sample of Vega-like sources both show UIR-bandemission, attributed to hydrocarbon materials. Detailed comparisons ofthe optical and IRAS positions suggest that in some cases the IRASsource is not physically associated with the visible star. Alternativeassociations are suggested for several of these sources. Fractionalexcess luminosities are derived from the observed spectral energydistributions. The values found are comparable to those measuredpreviously for other Vega-like sources.
| The ROSAT Bright Survey: II. Catalogue of all high-galactic latitude RASS sources with PSPC countrate CR > 0.2 s-1
We present a summary of an identification program of the more than 2000X-ray sources detected during the ROSAT All-Sky Survey (Voges et al.1999) at high galactic latitude, |b| > 30degr , with countrate above0.2 s-1. This program, termed the ROSAT Bright Survey RBS, isto more than 99.5% complete. A sub-sample of 931 sources with countrateabove 0.2 s-1 in the hard spectral band between 0.5 and 2.0keV is to 100% identified. The total survey area comprises 20391deg2 at a flux limit of 2.4 x 10-12 ergcm-2 s-1 in the 0.5 - 2.0 keV band. About 1500sources of the complete sample could be identified by correlating theRBS with SIMBAD and the NED. The remaining ~ 500 sources were identifiedby low-resolution optical spectroscopy and CCD imaging utilizingtelescopes at La Silla, Calar Alto, Zelenchukskaya and Mauna Kea. Apartfrom completely untouched sources, catalogued clusters and galaxieswithout published redshift as well as catalogued galaxies with unusualhigh X-ray luminosity were included in the spectroscopic identificationprogram. Details of the observations with an on-line presentation of thefinding charts and the optical spectra will be published separately.Here we summarize our identifications in a table which contains opticaland X-ray information for each source. As a result we present the mostmassive complete sample of X-ray selected AGNs with a total of 669members and a well populated X-ray selected sample of 302 clusters ofgalaxies with redshifts up to 0.70. Three fields studied by us remainwithout optical counterpart (RBS0378, RBS1223, RBS1556). While the firstis a possible X-ray transient, the two latter are isolated neutron starcandidates (Motch et al. 1999, Schwope et al. 1999).
| The ROSAT all-sky survey catalogue of the nearby stars
We present X-ray data for all entries of the Third Catalogue of NearbyStars \cite[(Gliese & Jahreiss 1991)]{gli91} that have been detectedas X-ray sources in the ROSAT all-sky survey. The catalogue contains1252 entries yielding an average detection rate of 32.9 percent. Inaddition to count rates, source detection parameters, hardness ratios,and X-ray fluxes we also list X-ray luminosities derived from Hipparcosparallaxes. Catalogue also available at CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Metallicity effects on the chromospheric activity-age relation for late-type dwarfs
We show that there is a relationship between the age excess, defined asthe difference between the stellar isochrone and chromospheric ages, andthe metallicity as measured by the index [Fe/H] for late-type dwarfs.The chromospheric age tends to be lower than the isochrone age formetal-poor stars, and the opposite occurs for metal-rich objects. Wesuggest that this could be an effect of neglecting the metallicitydependence of the calibrated chromospheric emission-age relation. Wepropose a correction to account for this dependence. We also investigatethe metallicity distributions of these stars, and show that there aredistinct trends according to the chromospheric activity level. Inactivestars have a metallicity distribution which resembles the metallicitydistribution of solar neighbourhood stars, while active stars appear tobe concentrated in an activity strip on the logR'_HKx[Fe/H] diagram. Weprovide some explanations for these trends, and show that thechromospheric emission-age relation probably has different slopes on thetwo sides of the Vaughan-Preston gap.
| Candidate Main-Sequence Stars with Debris Disks: A New Sample of Vega-like Sources
Vega-like sources are main-sequence stars that exhibit IR fluxes inexcess of expectations for stellar photospheres, most likely due toreradiation of stellar emission intercepted by orbiting dust grains. Wehave identified a large sample of main-sequence stars with possibleexcess IR radiation by cross-correlating the Michigan Catalog ofTwo-dimensional Spectral Types for the HD Stars with the IRAS FaintSource Survey Catalog. Some 60 of these Vega-like sources were not foundduring previous surveys of the IRAS database, the majority of whichemployed the lower sensitivity Point Source Catalog. Here, we providedetails of our search strategy, together with a preliminary examinationof the full sample of Vega-like sources.
| The ROSAT all-sky survey catalogue of optically bright main-sequence stars and subgiant stars
We present X-ray data for all main-sequence and subgiant stars ofspectral types A, F, G, and K and luminosity classes IV and V listed inthe Bright Star Catalogue that have been detected as X-ray sources inthe ROSAT all-sky survey; several stars without luminosity class arealso included. The catalogue contains 980 entries yielding an averagedetection rate of 32 percent. In addition to count rates, sourcedetection parameters, hardness ratios, and X-ray fluxes we also listX-ray luminosities derived from Hipparcos parallaxes. The catalogue isalso available in electronic form via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Determination of the temperatures of selected ISO flux calibration stars using the Infrared Flux Method
Effective temperatures for 420 stars with spectral types between A0 andK3, and luminosity classes between II and V, selected for a fluxcalibration of the Infrared Space Observatory, ISO, have been determinedusing the Infrared Flux Method (IRFM). The determinations are based onnarrow and wide band photometric data obtained for this purpose, andtake into account previously published narrow-band measures oftemperature. Regression coefficients are given for relations between thedetermined temperatures and the photometric parameters (B2-V1), (b-y)and (B-V), corrected for interstellar extinction through use ofHipparcos parallaxes. A correction for the effect of metallicity on thedetermination of integrated flux is proposed. The importance of aknowledge of metallicity in the representation of derived temperaturesfor Class V, IV and III stars by empirical functions is discussed andformulae given. An estimate is given for the probable error of eachtemperature determination. Based on data from the ESA HipparcosAstrometry Satellite.
| X-ray/optical observations of stars with shallow convection zones (A8-G2 V)
We present Walraven photometry and ROSAT All-Sky Survey data for asample of 173 bright main-sequence stars with spectral types between A8Vand G2V\@. These observations are part of a study of the onset ofmagnetic surface activity along the main sequence. Values for theeffective temperature, surface gravity and interstellar reddening havebeen obtained from a comparison of the observed Walraven colours withtheoretical values. These parameters have been used to derive accurateX-ray\ surface flux densities.
| The catalogue of nearby stars metallicities.
Not Available
| A Survey of Ca II H and K Chromospheric Emission in Southern Solar-Type Stars
More than 800 southern stars within 50 pc have been observed forchromospheric emission in the cores of the Ca II H and K lines. Most ofthe sample targets were chosen to be G dwarfs on the basis of colors andspectral types. The bimodal distribution in stellar activity first notedin a sample of northern stars by Vaughan and Preston in 1980 isconfirmed, and the percentage of active stars, about 30%, is remarkablyconsistent between the northern and southern surveys. This is especiallycompelling given that we have used an entirely different instrumentalsetup and stellar sample than used in the previous study. Comparisons tothe Sun, a relatively inactive star, show that most nearby solar-typestars have a similar activity level, and presumably a similar age. Weidentify two additional subsamples of stars -- a very active group, anda very inactive group. The very active group may be made up of youngstars near the Sun, accounting for only a few percent of the sample, andappears to be less than ~0.1 Gyr old. Included in this high-activitytail of the distribution, however, is a subset of very close binaries ofthe RS CVn or W UMa types. The remaining members of this population maybe undetected close binaries or very young single stars. The veryinactive group of stars, contributting ~5%--10% to the total sample, maybe those caught in a Maunder Minimum type phase. If the observations ofthe survey stars are considered to be a sequence of snapshots of the Sunduring its life, we might expect that the Sun will spend about 10% ofthe remainder of its main sequence life in a Maunder Minimum phase.
| Stars resembling the Sun
This review is primarily directed to the question whether photometricsolar analogues remain such when subjected to detailed spectroscopicanalyses and interpreted with the help of internal stucture models. Inother words, whether the physical parameters: mass, chemicalcomposition, age (determining effective temperature and luminosity),chromospheric activity, equatorial rotation, lithium abundance, velocityfields etc., we derive from the spectral analysis of a photometric solaranalogue, are really close to those of the Sun. We start from 109photometric solar analogues extracted from different authors. The starsselected had to satisfy three conditions: i) their colour index (B-V)must be contained in the interval: Δ (B-V) = 0.59-0.69, ii) theymust possess a trigonometric parallax, iii) they must have undergone ahigh resolution detailed spectroscopic analysis. First, this reviewpresents photometric and spectrophotometric researches on solaranalogues and recalls the pionneering work on these stars by the lateJohannes Hardorp. After a brief discussion on low and high resolutionspectroscopic researches, a comparison is made between effectivetemperatures as obtained, directly, from detailed spectral analyses andthose obtained, indirectly, from different photometric relations. Aninteresting point in this review is the discussion on the tantalilizingvalue of the (B-V)solar of the Sun, and the presentation of anew reliable value of this index. A short restatement of the kinematicproperties of the sample of solar analogues is also made. And, finally,the observational ( T eff, M bol) diagram,obtained with 99 of the initially presented 109 analogues, is comparedto a theoretical ( T eff, M bol) diagram. Thislatter has been constructed with a grid of internal structure models forwhich, (very important for this investigation), the Sun was used asgauge. In analysing the position, with respect to the Sun, of each starwe hoped to find a certain number of stars tightly neighbouring the Sunin mass, chemical composition and state of evolution. The surprisingresult is that the stars occupy in this HR Diagram a rather extendedregion around the Sun, many of them seem more evolved and older than theSun, and only 4 of the evolved stars seem younger. The age of some starsin the sample is also discussed in terms of chromospheric activity andLi-content. Our conclusion is much the same as that contained inprevious papers we have written on the subject: in spite of a muchlarger number of stars, we have not been able to nominate a single starof the sample for a ``perfect good solar twin''. Another aim inbeginning, 25 years ago, this search for solar analogues, was to haveready a bunch of stars resembling the Sun and analysed spectroscopicallyin detail, in order that, when planets hunters of solar type stars,finally would have found such a specimen, we would have been able toimmediately compare the physical parameters of this star to those of theSun. We have been lucky enough: one of the good solar analogues wepresent herewith, is 51 Pegasi (HD 217014) which, according to the veryrecent observations by Mayor and Queloz (1995), has a planet orbitingaround it. And what is more: two other stars possessing planets: 47Ursae Majoris (HD 95128) and 70 Virginis (HD 117176), have just beendiscovered by Marcy and Butler (187th Meeting of the AAS,January 1996). One of them, 47 Ursae Majoris, is also included in thelist of photometric solar analogues. The other star, 70 Virginis, hasonly been included after the ``Planets News'', because the colour index(B-V) of this star is slightly higher than the prescribted limit of theselection, (B-V = 0.71, instead, 0.69). It would have been a pity toleave the third '' planet star out of the competition.
| LUCIFERS: A Photoelectric Radial-Velocity Spectrometer at MT John University Observatory
Not Available
| Chemistry and Kinematics in the Solar Neighborhood: Implications for Stellar Populations and for Galaxy Evolution
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....110.2771W&db_key=AST
| Ca II H and K Filter Photometry on the UVBY System. II. The Catalog of Observations
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....109.2828T&db_key=AST
| 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.
| Stroemgren photometry of F- and G-type stars brighter than V = 9.6. I. UVBY photometry
Within the framework of a large photometric observing program, designedto investigate the Galaxy's structure and evolution, Hβ photometryis being made for about 9000 stars. As a by-product, supplementary uvbyphotometry has been made. The results are presented in a cataloguecontaining 6924 uvby observations of 6190 stars, all south ofδ=+38deg. The overall internal rms errors of one observation(transformed to the standard system) of a program star in the interval6.5
| A narrow-band search for extraterrestrial intelligence (SETI) using the interstellar contact channel hypothesis
A search is reported for narrow spectral line emission from 176 targets(including 166 stars and seven globular clusers) at the hypothesized'interstellar communications channel' frequency of 4.462336275 GHz (= pitimes the neutral hydrogen line at 1.42 GHz) using the Parkes Radiotelescope. The frequency was Doppler corrected for the solar barycenter,target barycenter, and cosmic microwave background (CMB) referenceframes. If a 'Galactic club' of extraterrestrial civilizations exists,then the null results, down to a 3 sigma limit of 2 Jy (6 Jy in CMBframe), set an upper limit of 10 exp 8 yr on the lifetime of suchcivilizations.
| Search for Vega-like nearby stars with 12 micron excess
The identification of Vega-like main-sequence stars with 10-micronexcess would permit important measurements of the spatial extent of theradiating material with ground-based telescopes. In fact, 55 of the 548nearby A, F, G, and K dwarfs with IRAS catalog magnitudes at 12 micronsappear to have excess 12-micron flux. However, for only two of thesestars, Beta Pic and Zeta Lep, was it possible, using small-aperturephotometry at 2.2 and 10 microns, to verify that the 12-micron excess iswith high likelihood associated with the star. For the remaining starsthe apparent 12-micron color of the 106 A, F, G, and K stars in theobserving program is only 0.02 mag. Excess flux due to a Vega-like cloudwhich may surround some of the sources in the observing program, likeAlpha Lyrae, is thus typically not detectable at 10 microns.
| JHKLM standard stars in the ESO system
A list of 199 standard stars suitable for the ESO standard photometricsystem at JHKLM is given. Faint stars (although brighter than K = 7.7)to be used on larger telescopes are included. This list is based on ananalysis of all infrared photometric observations carried out at LaSilla from 1979 until 1989 inclusive. The accuracy of the data (about0.02 mag. at J, H, K, L, and M) is similar to the one achieved at SAAOand CTIO. Comparisons with these systems, as well as with the AAO andMSSO systems, are made: it is shown that the ESO system is very close tothe other ones, with the exception of CTIOs.
| BVRI photometry of the Gliese Catalogue stars
Photoelectri BVRI photometry on the Cousins (Kron-Cape) system has beenobtained for many of the southern faint stars in the Gliese Catalog(1969). This extends the work of Cousins (1980) and provides a uniformset of data for the nearby stars. Several red dwarfs are noted, whichwere used to define the red end of the Cousins system.
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Osservazione e dati astrometrici
| Costellazione: | Ottante |
| Ascensione retta: | 01h37m55.60s |
| Declinazione: | -82°58'30.0" |
| Magnitudine apparente: | 5.87 |
| Distanza: | 27.13 parsec |
| Moto proprio RA: | 121.8 |
| Moto proprio Dec: | 120.7 |
| B-T magnitude: | 6.613 |
| V-T magnitude: | 5.947 |
Cataloghi e designazioni:
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INHABITED SKY
