Observation and modelling of main-sequence star chromospheres - XVI. Rotation of dK5 stars
Using two different spectrographs, High Accuracy Radial velocity PlanetSearch (HARPS) (European Southern Observatory) and SOPHIE (Observatoirede Haute Provence), we have measured v sin i for a sample of dK5 stars.These are the first measurements of v sin i for most of the starsstudied here.We measured v sin i to an accuracy of 0.3 km s-1 and adetection limit of about 0.5-1 km s-1. All our targets havesimilar (R - I)c colour. This is an advantage and facilitatesthe determination of the narrowest line profiles for v sin i ˜ 0.In our total sample, we detected rotation for 22 stars (three dK5e and19 dK5 stars), and we did not detect rotation in a further 22 stars.This result shows that there are many dK5 slow rotators, and many morethan for dM1 stars. We also report on a newly discovered dK5e star, McC522, which is also the fastest rotator in our sample.We determine radii and effective temperatures for all our target stars.The effective temperatures were derived using the (R - I)ccolour and empirical far-red colour-effective temperature correlations,and the radii were derived from the standard formulae relatingMbol, bolometric correction and Teff.We find that the distribution of P/sin i (the projected rotation period)is rather homogeneous, i.e. the distribution of the 22 detected stars asa function of P/sin i is approximately flat and does not show anymaximum, unlike for dM1 stars, a close spectral type. We find that thedistribution in v sin i is bimodal, as in dM1 stars, with fast dK5erotators and slower dK5 rotators. Based on observations available atObservatoire de Haute Provence and the European Southern Observatorydata bases and on Hipparcos parallax measurements.
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The effect of activity on stellar temperatures and radii
Context: Recent analyses of low-mass eclipsing binary stars haveunveiled a significant disagreement between the observations andpredictions of stellar structure models. Results show that theoreticalmodels underestimate the radii and overestimate the effectivetemperatures of low-mass stars but yield luminosities that accord withobservations. A hypothesis based upon the effects of stellar activitywas put forward to explain the discrepancies. Aims: In this paper westudy the existence of the same trend in single active stars and providea consistent scenario to explain systematic differences between activeand inactive stars in the H-R diagram reported earlier. Methods: Theanalysis is done using single field stars of spectral types late-K and Mand computing their bolometric magnitudes and temperatures throughinfrared colours and spectral indices. The properties of the stars insamples of active and inactive stars are compared statistically toreveal systematic differences. Results: After accounting for a numberof possible bias effects, active stars are shown to be cooler thaninactive stars of similar luminosity therefore implying a larger radiusas well, in proportions that are in excellent agreement with those foundfrom eclipsing binaries. Conclusions: The present results generalisethe existence of strong radius and temperature dependences on stellaractivity to the entire population of low-mass stars, regardless of theirmembership in close binary systems.Tables 1 and 2 are 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/478/507
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Proper-motion binaries in the Hipparcos catalogue. Comparison with radial velocity data
Context: .This paper is the last in a series devoted to the analysis ofthe binary content of the Hipparcos Catalogue. Aims: .Thecomparison of the proper motions constructed from positions spanning ashort (Hipparcos) or long time (Tycho-2) makes it possible to uncoverbinaries with periods of the order of or somewhat larger than the shorttime span (in this case, the 3 yr duration of the Hipparcos mission),since the unrecognised orbital motion will then add to the propermotion. Methods: .A list of candidate proper motion binaries isconstructed from a carefully designed χ2 test evaluatingthe statistical significance of the difference between the Tycho-2 andHipparcos proper motions for 103 134 stars in common between the twocatalogues (excluding components of visual systems). Since similar listsof proper-motion binaries have already been constructed, the presentpaper focuses on the evaluation of the detection efficiency ofproper-motion binaries, using different kinds of control data (mostlyradial velocities). The detection rate for entries from the NinthCatalogue of Spectroscopic Binary Orbits (S_B^9) is evaluated, as wellas for stars like barium stars, which are known to be all binaries, andfinally for spectroscopic binaries identified from radial velocity datain the Geneva-Copenhagen survey of F and G dwarfs in the solarneighbourhood. Results: .Proper motion binaries are efficientlydetected for systems with parallaxes in excess of ~20 mas, and periodsin the range 1000-30 000 d. The shortest periods in this range(1000-2000 d, i.e., once to twice the duration of the Hipparcos mission)may appear only as DMSA/G binaries (accelerated proper motion in theHipparcos Double and Multiple System Annex). Proper motion binariesdetected among S_B9 systems having periods shorter than about400 d hint at triple systems, the proper-motion binary involving acomponent with a longer orbital period. A list of 19 candidate triplesystems is provided. Binaries suspected of having low-mass(brown-dwarf-like) companions are listed as well. Among the 37 bariumstars with parallaxes larger than 5 mas, only 7 exhibit no evidence forduplicity whatsoever (be it spectroscopic or astrometric). Finally, thefraction of proper-motion binaries shows no significant variation amongthe various (regular) spectral classes, when due account is taken forthe detection biases.Full Table [see full textsee full text] is 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/464/377
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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
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Statistical Constraints for Astrometric Binaries with Nonlinear Motion
Useful constraints on the orbits and mass ratios of astrometric binariesin the Hipparcos catalog are derived from the measured proper motiondifferences of Hipparcos and Tycho-2 (Δμ), accelerations ofproper motions (μ˙), and second derivatives of proper motions(μ̈). It is shown how, in some cases, statistical bounds can beestimated for the masses of the secondary components. Two catalogs ofastrometric binaries are generated, one of binaries with significantproper motion differences and the other of binaries with significantaccelerations of their proper motions. Mathematical relations betweenthe astrometric observables Δμ, μ˙, and μ̈ andthe orbital elements are derived in the appendices. We find a remarkabledifference between the distribution of spectral types of stars withlarge accelerations but small proper motion differences and that ofstars with large proper motion differences but insignificantaccelerations. The spectral type distribution for the former sample ofbinaries is the same as the general distribution of all stars in theHipparcos catalog, whereas the latter sample is clearly dominated bysolar-type stars, with an obvious dearth of blue stars. We point outthat the latter set includes mostly binaries with long periods (longerthan about 6 yr).
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The Palomar/MSU Nearby Star Spectroscopic Survey. III. Chromospheric Activity, M Dwarf Ages, and the Local Star Formation History
We present high-resolution echelle spectroscopy of 676 nearby M dwarfs.Our measurements include radial velocities, equivalent widths ofimportant chromospheric emission lines, and rotational velocities forrapidly rotating stars. We identify several distinct groups by theirHα properties and investigate variations in chromospheric activityamong early (M0-M2.5) and mid (M3-M6) dwarfs. Using a volume-limitedsample together with a relationship between age and chromosphericactivity, we show that the rate of star formation in the immediate solarneighborhood has been relatively constant over the last 4 Gyr. Inparticular, our results are inconsistent with recent large bursts ofstar formation. We use the correlation between Hα activity and ageas a function of color to set constraints on the properties of L and Tdwarf secondary components in binary systems. We also identify a numberof interesting stars, including rapid rotators, radial velocityvariables, and spectroscopic binaries. Observations were made at the 60inch telescope at Palomar Mountain, which is jointly owned by theCalifornia Institute of Technology and the Carnegie Institution ofWashington.
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Photometric Measurements of the Fields of More than 700 Nearby Stars
In preparation for optical/IR interferometric searches for substellarcompanions of nearby stars, we undertook to characterize the fields ofall nearby stars visible from the Northern Hemisphere to determinesuitable companions for interferometric phase referencing. Because theKeck Interferometer in particular will be able to phase-reference oncompanions within the isoplanatic patch (30") to about 17th magnitude atK, we took images at V, r, and i that were deep enough to determine iffield stars were present to this magnitude around nearby stars using aspot-coated CCD. We report on 733 fields containing 10,629 measurementsin up to three filters (Gunn i, r and Johnson V) of nearby stars down toabout 13th magnitude at V.
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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
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The Palomar/MSU Nearby Star Spectroscopic Survey.II.The Southern M Dwarfs and Investigation of Magnetic Activity
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....112.2799H&db_key=AST
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The Palomar/MSU Nearby-Star Spectroscopic Survey. I. The Northern M Dwarfs -Bandstrengths and Kinematics
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....110.1838R&db_key=AST
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The general catalogue of trigonometric [stellar] paralaxes
Not Available
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Preliminary Version of the Third Catalogue of Nearby Stars
Not Available
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Parallaxes and proper motions. XVIII
Parallaxes and proper motions are presented for 32 stars in 26starfields. At least 13 of the stars have been designated as subdwarfson the basis of spectral classification. The list consists entirely ofobservations measured on the PDS machine at Yale Observatory. Theexternal standard errors in parallax are about half of those found inprevious lists in this series.
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Catalogue of stars with CaII H and K emissions
Not Available
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The luminosity law for late-type main-sequence stars in the solar neighborhood
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974PASP...86..697E&db_key=AST
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Calcium emission intensities as indicators of stellar age.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970MNRAS.148..463W&db_key=AST
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Radial velocities of dK and dM stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1967AJ.....72..905W&db_key=AST
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Photovisual magnitudes of 418 dwarf M stars and 34 parallax stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956AJ.....61..219S&db_key=AST
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Dwarf M stars found spectrophotometrically .
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956AJ.....61..201V&db_key=AST
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INHABITED SKY
