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Mt. Suhora Survey - Searching for Pulsating M Dwarfs. II
We present our report on the second part of our ongoing project whichaims at finding stellar pulsations in early type M dwarfs. Our search isbased on time-series photometric data acquired mainly at Mt. SuhoraObservatory, though, several stars have been observed from other sites.Data of 49 M dwarfs are included in this paper. We analyzed the data bymeans of the Fourier technique as well as Phase Dispersion Minimizationmethod. We still cannot confirm any pulsating M dwarf at themodel-predicted period of 23-40 min. In addition to our main goal wesearched for flare activities, planetary transits and other types ofbrightness changes. We did find several new variable stars, includingpulsating stars, binary systems and flare stars, however, only flaring Mdwarfs are presented in this paper.
| Bayesian inference of stellar parameters and interstellar extinction using parallaxes and multiband photometry
Astrometric surveys provide the opportunity to measure the absolutemagnitudes of large numbers of stars, but only if the individualline-of-sight extinctions are known. Unfortunately, extinction is highlydegenerate with stellar effective temperature when estimated frombroad-band optical/infrared photometry. To address this problem, Iintroduce a Bayesian method for estimating the intrinsic parameters of astar and its line-of-sight extinction. It uses both photometry andparallaxes in a self-consistent manner in order to provide anon-parametric posterior probability distribution over the parameters.The method makes explicit use of domain knowledge by employing theHertzsprung-Russell Diagram (HRD) to constrain solutions and to ensurethat they respect stellar physics. I first demonstrate this method byusing it to estimate effective temperature and extinction from BVJHKdata for a set of artificially reddened Hipparcos stars, for whichaccurate effective temperatures have been estimated from high-resolutionspectroscopy. Using just the four colours, we see the expected strongdegeneracy (positive correlation) between the temperature andextinction. Introducing the parallax, apparent magnitude and the HRDreduces this degeneracy and improves both the precision (reduces theerror bars) and the accuracy of the parameter estimates, the latter byabout 35 per cent. The resulting accuracy is about 200 K in temperatureand 0.2 mag in extinction. I then apply the method to estimate theseparameters and absolute magnitudes for some 47 000 F, G, K Hipparcosstars which have been cross-matched with Two-Micron All-Sky Survey(2MASS). The method can easily be extended to incorporate the estimationof other parameters, in particular metallicity and surface gravity,making it particularly suitable for the analysis of the 109stars from Gaia.
| Discoveries from a Near-infrared Proper Motion Survey Using Multi-epoch Two Micron All-Sky Survey Data
We have conducted a 4030 deg2 near-infrared proper motionsurvey using multi-epoch data from the Two Micron All-Sky Survey(2MASS). We find 2778 proper motion candidates, 647 of which are notlisted in SIMBAD. After comparison to Digitized Sky Survey images, wefind that 107 of our proper motion candidates lack counterparts at B, R,and I bands and are thus 2MASS-only detections. We present results ofspectroscopic follow-up of 188 targets that include the infrared-onlysources along with selected optical-counterpart sources with faintreduced proper motions or interesting colors. We also establish a set ofnear-infrared spectroscopic standards with which to anchor near-infraredclassifications for our objects. Among the discoveries are six youngfield brown dwarfs, five "red L" dwarfs, three L-type subdwarfs, twelveM-type subdwarfs, eight "blue L" dwarfs, and several T dwarfs. Wefurther refine the definitions of these exotic classes to aid futureidentification of similar objects. We examine their kinematics and findthat both the "blue L" and "red L" dwarfs appear to be drawn from arelatively old population. This survey provides a glimpse of the kindsof research that will be possible through time-domain infrared projectssuch as the UKIDSS Large Area Survey, various VISTA surveys, and WISE,and also through z- or y-band enabled, multi-epoch surveys such asPan-STARRS and LSST.Some of the spectroscopic data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership amongthe California Institute of Technology, the University of California,and the National Aeronautics and Space Administration. The Observatorywas made possible by the generous financial support of the W. M. KeckFoundation. Other spectroscopic data were collected at the SubaruTelescope, which is operated by the National Astronomical Observatory ofJapan.
| The High Angular Resolution Multiplicity of Massive Stars
We present the results of a speckle interferometric survey of Galacticmassive stars that complements and expands upon a similar survey madeover a decade ago. The speckle observations were made with the Kitt PeakNational Observatory and Cerro Tololo Inter-American Observatory 4 mtelescopes and USNO speckle camera, and they are sensitive to thedetection of binaries in the angular separation regime between 0farcs03and 5'' with relatively bright companions (ΔV < 3). We reporton the discovery of companions to 14 OB stars. In total we resolvedcompanions of 41 of 385 O-stars (11%), 4 of 37 Wolf-Rayet stars (11%),and 89 of 139 B-stars (64%; an enriched visual binary sample that weselected for future orbital determinations). We made a statisticalanalysis of the binary frequency among the subsample that are listed inthe Galactic O Star Catalog by compiling published data on other visualcompanions detected through adaptive optics studies and/or noted in theWashington Double Star Catalog and by collecting published informationon radial velocities and spectroscopic binaries. We find that the binaryfrequency is much higher among O-stars in clusters and associationscompared to the numbers for field and runaway O-stars, consistent withpredictions for the ejection processes for runaway stars. We present afirst orbit for the O-star δ Orionis; a linear solution of theclose, apparently optical, companion of the O-star ι Orionis; andan improved orbit of the Be star δ Scorpii. Finally, we listastrometric data for another 249 resolved and 221 unresolved targetsthat are lower mass stars that we observed for various other scienceprograms.
| 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
| Speckle interferometry of nearby multiple stars. IV. Measurements in 2004 and new orbits
The results of speckle interferometric observations of 104 binary and 6triple stars performed at the BTA 6 m telescope in 2004 October arepresented. Nearby low-mass stars are mostly observed for the program,among which 59 there are new binaries recently discovered by theHipparcos astrometric satellite. Concurrently with thediffraction-limited position measurements we obtained 154 brightnessratio measurements of binary and multiple star components in differentbands of the visible spectrum. New, first-resolved binaries are thesymbiotic star CH Cyg with a weak companion at 0.043″ separationand the pair of red dwarfs, GJ 913 = HIP 118212. In addition, we derivedthe orbital parameters for two interferometric systems: the CN-giantpair HD 210211 = HIP 109281 (P = 10.7 yr) and the G2V-K2V G2V-K2V binaryGJ 9830 = HIP 116259 (P = 15.7 yr).
| Orbits of new Hipparcos binaries. II
We continue the presentation of new orbits for Hipparcos binariesdetermined from regular speckle interferometric observations. Most ofthe data were collected in the period between 1998.77 and 2004.82 usingthe 6 m BTA telescopeof the Special Astrophysical Observatory in Zelenchuk. New orbits arepresented for six pairs: HIP 4809, HIP 4849,HIP 5531, HIP 19206, HIP 105947, andHIP 114922. One of the pairs, HIP 114922, has M dwarfcomponents orbiting with a period of 19.72 yr. Two binaries,HIP 4809 and HIP 5531, have luminosity class IVcomponents. The periods of the orbits range from 7.30 yr to 28.99 yr.All of the orbits can be considered definitive; however, the total masserror for the systems remains high, mainly due to Hipparcos parallaxerror.
| Speckle interferometry of nearby multiple stars. III.
Not Available
| A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)
The LSPM catalog is a comprehensive list of 61,977 stars north of theJ2000 celestial equator that have proper motions larger than 0.15"yr-1 (local-background-stars frame). The catalog has beengenerated primarily as a result of our systematic search for high propermotion stars in the Digitized Sky Surveys using our SUPERBLINK software.At brighter magnitudes, the catalog incorporates stars and data from theTycho-2 Catalogue and also, to a lesser extent, from the All-SkyCompiled Catalogue of 2.5 million stars. The LSPM catalog considerablyexpands over the old Luyten (Luyten Half-Second [LHS] and New LuytenTwo-Tenths [NLTT]) catalogs, superseding them for northern declinations.Positions are given with an accuracy of <~100 mas at the 2000.0epoch, and absolute proper motions are given with an accuracy of ~8 masyr-1. Corrections to the local-background-stars propermotions have been calculated, and absolute proper motions in theextragalactic frame are given. Whenever available, we also give opticalBT and VT magnitudes (from Tycho-2, ASCC-2.5),photographic BJ, RF, and IN magnitudes(from USNO-B1 catalog), and infrared J, H, and Ks magnitudes(from 2MASS). We also provide an estimated V magnitude and V-J color fornearly all catalog entries, useful for initial classification of thestars. The catalog is estimated to be over 99% complete at high Galacticlatitudes (|b|>15deg) and over 90% complete at lowGalactic latitudes (|b|>15deg), down to a magnitudeV=19.0, and has a limiting magnitude V=21.0. All the northern starslisted in the LHS and NLTT catalogs have been reidentified, and theirpositions, proper motions, and magnitudes reevaluated. The catalog alsolists a large number of completely new objects, which promise to expandvery significantly the census of red dwarfs, subdwarfs, and white dwarfsin the vicinity of the Sun.Based on data mining of the Digitized Sky Surveys (DSSs), developed andoperated by the Catalogs and Surveys Branch of the Space TelescopeScience Institute (STScI), Baltimore.Developed with support from the National Science Foundation (NSF), aspart of the NASA/NSF NStars program.
| Differential photometry of speckle-interferometric binary and multiple stars
A method for differential photometry of speckle-interferometric binaryand multiple stars is presented. Both the accuracy and sources ofsystematic errors of the method are analysed. The photometric accuracyranges between 0.02 m and 0.20 m, depending on the atmospheric seeing,the brightness and the separation of the system components. A comparisonbetween our magnitude differences and those of other authors ispresented.
| Speckle interferometry of nearby multiple stars. II.
This paper is a continuation of diffraction-limited speckleinterferometry of binary and multiple stars carried out at the 6-mtelescope of the Special Astrophysical Observatory in Zelenchuk. Theprogram has concentrated on nearby (π>10 mas) close binariesdiscovered or measured during the Hipparcos mission. Here, we present132 measurements of relative positions and magnitude differences for 99pairs and 8 measurements for 6 triple systems. 54 entries in the paperare new Hipparcos binaries. New triple systems with late-type dwarfcomponents, discovered in the course of observations, are HIP 8533 andHIP 25354.Based on data collected at the Special Astrophysical Observatory,Russia.{Tables 1-3 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?/A+A/422/627
| Improved Astrometry and Photometry for the Luyten Catalog. II. Faint Stars and the Revised Catalog
We complete construction of a catalog containing improved astrometry andnew optical/infrared photometry for the vast majority of NLTT starslying in the overlap of regions covered by POSS I and by the secondincremental Two Micron All Sky Survey (2MASS) release, approximately 44%of the sky. The epoch 2000 positions are typically accurate to 130 mas,the proper motions to 5.5 mas yr-1, and the V-J colors to0.25 mag. Relative proper motions of binary components are measured to 3mas yr-1. The false-identification rate is ~1% for11<~V<~18 and substantially less at brighter magnitudes. Theseimprovements permit the construction of a reduced proper-motion diagramthat, for the first time, allows one to classify NLTT stars intomain-sequence (MS) stars, subdwarfs (SDs), and white dwarfs (WDs). We inturn use this diagram to analyze the properties of both our catalog andthe NLTT catalog on which it is based. In sharp contrast to popularbelief, we find that NLTT incompleteness in the plane is almostcompletely concentrated in MS stars, and that SDs and WDs are detectedalmost uniformly over the sky δ>-33deg. Our catalogwill therefore provide a powerful tool to probe these populationsstatistically, as well as to reliably identify individual SDs and WDs.
| An H-alpha survey of neglected Vyssotsky Catalog stars
Consideration is given to a significant number of Vyssotsky K- andM-dwarfs that have either no published radial velocity (71 stars), or avelocity based on a single measure (22), or with an uncertaintly greaterthan 5 km/s (19). An 'in flare' observation of Vys 250A compared to itsquiescent state, and an example of the double-lined phase of Vys 250Bare illustrated. Mean values from the observations are given in tabularform.
| 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
| 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
| Photometry of dwarf K and M stars
An observational program using UBVRI photometry is presented for 688stars from among the dwarf K and M stars already found spectroscopicallyby Vyssotsky (1958). Of these, 211 have not been observedphotometrically. These observations were obtained over a period ofseveral years at the Kitt Peak National Observatory using a GaAsphotomultiplier with an 0.9 m reflector. Based on night-to-nightvariations in the measures of individual stars, the internal errors maybe estimated to be roughly 0.01 mag for the colors and 0.015 for the Vmagnitudes. The photometric parallaxes reported for each star werecomputed in the manner discussed by Weis (1986).
| Photometry of dwarf K and M stars
Broadband photometry in BVRI colors for 120 nearby dwarf K and M starsis presented. The apparent magnitude distributions of Vyssotsky and VanVleck stars with photometry and without photometry are studied. Therelationship between apparent and photoelectric magnitudes is analyzed.The proper motion and transverse velocity of the two star types areexamined and compared.
| Dwarf K and M stars of high proper motion found in a hemispheric survey
A recently completed visual/red spectral region objective-prism surveyof more than half the sky found some 2200 dwarf K and M stars ofnegligible proper motion (Stephenson, 1986). The present paper adds the1800-odd spectroscopically identified dwarfs that did prove to havesignificant proper motions. About half of these had previous spectralclassifications of some sort, especially by Vyssotsky (1952, 1956). Forthe great majority, the present coordinates are more accurate thanprevious data. The paper includes about 50 stars with unpublishedparallaxes, likely to have parallaxes of 0.05 arcsec or more. Combiningthe present data with the first paper suggests that the number oflow-proper-motion stars in that paper was not unreasonable.
| New subdwarfs. IV - UBV photometry of 1690 high-proper-motion stars
A photometric list of 1690 stars of known high proper motion is used tosearch for potential high-velocity stars of various metallicity valuesin order to find candidates for trigonometric programs on subdwarfs andto enlarge the sample with which to study the relation between stellarkinematics and metal abundance. A list of 113 stars with tangentialspace velocities of 300 km/s or greater is obtained, the highesttangential velocity relative to the sun being 630 km/s. By using thevariation of the tangential velocity with longitude and adopting thegalactic rotation at the solar circle to be 220 km/s, the rotation ofthe subdwarf system is estimated at 0 + or - 50 km/s from the transversevelocity alone, in agreement with determinations based on other methods.
| Predicted infrared brightness of stars within 25 parsecs of the sun
Procedures are given for transforming selected optical data intoinfrared flux densities or irradiances. The results provide R, T(eff)blackbody approximations for about 2000 of the stars in Woolley et al.'sCatalog of Stars (1970) within 25 pc of the sun, and additional whitedwarfs, with infrared flux densities predicted for them at ninewavelengths from 2.2 to 101 microns including the Infrared AstronomySatellite bands.
| The degree of completeness of nearby stars and the stellar luminosity function
The aim of this study is the determination of the degree of completenessof nearby star catalogs for stars of as many spectral classes aspossible, by means of a novel method which eliminates giants, subgiantsand white dwarfs from the data sample. It is shown that main-sequencestars earlier than M0 are essentially complete and identified withinabout 20 pc of the sun, by determining V/V(max) as a function of B-V forthe main sequence stars. The luminosity function produced by the M0stars has been known to differ from the commonly accepted and smoothedluminosity function, which increases monotonically with absolutemagnitude, between the absolute visual magnitudes +6 and +9. It isconcluded that the deficiency between these magnitude limits is real,suggesting either (1) that stars of masses equivalent to this absolutemagnitude range are rarer than those of greater mass, or (2) that themass-luminosity relation is not as linear as is believed at present.
| Spectral types for proper motion stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975AJ.....80..239B&db_key=AST
| Lowell proper motions III : proper motion survey of the Northern Hemisphere with the 13-inch photographic telescope of the Lowell Observatory
Not Available
| 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
| 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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Dades d'Observació i Astrometria
| Constel·lació: | Pegasus |
| Ascensió Recta: | 23h16m39.72s |
| Declinació: | +19°37'17.1" |
| Magnitud Aparent: | 11.237 |
| Distancia: | 31.746 parsecs |
| Moviment propi RA: | -178.4 |
| Moviment propi Dec: | -182 |
| B-T magnitude: | 12.929 |
| V-T magnitude: | 11.377 |
Catàlegs i designacions:
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