Contents
Images
Upload your image
DSS Images Other Images
Related articles
Improved equations for eccentricity generation in hierarchical triple systems
In a series of papers, we developed a technique for estimating the innereccentricity in hierarchical triple systems, with the inner orbit beinginitially circular. However, for certain combinations of the masses andthe orbital elements, the secular part of the solution failed. In thispaper, we derive a new solution for the secular part of the innereccentricity, which corrects the previous weakness. The derivationapplies to hierarchical triple systems with coplanar and initiallycircular orbits. The new formula is tested numerically by integratingthe full equations of motion for systems with mass ratios from10-3 to 103. We also present more numericalresults for short-term eccentricity evolution, in order to get a betterpicture of the behaviour of the inner eccentricity.
| Effective temperature scale and bolometric corrections from 2MASS photometry
We present a method to determine effective temperatures, angularsemi-diameters and bolometric corrections for population I and II FGKtype stars based on V and 2MASS IR photometry. Accurate calibration isaccomplished by using a sample of solar analogues, whose averagetemperature is assumed to be equal to the solar effective temperature of5777 K. By taking into account all possible sources of error we estimateassociated uncertainties to better than 1% in effective temperature andin the range 1.0-2.5% in angular semi-diameter for unreddened stars.Comparison of our new temperatures with other determinations extractedfrom the literature indicates, in general, remarkably good agreement.These results suggest that the effective temperaure scale of FGK starsis currently established with an accuracy better than 0.5%-1%. Theapplication of the method to a sample of 10 999 dwarfs in the Hipparcoscatalogue allows us to define temperature and bolometric correction (Kband) calibrations as a function of (V-K), [m/H] and log g. Bolometriccorrections in the V and K bands as a function of T_eff, [m/H] and log gare also given. We provide effective temperatures, angularsemi-diameters, radii and bolometric corrections in the V and K bandsfor the 10 999 FGK stars in our sample with the correspondinguncertainties.
| Eccentricity generation in hierarchical triple systems: the planetary regime
In previous papers, we developed a technique for estimating the innereccentricity in hierarchical triple systems, with the inner orbit beinginitially circular. We considered systems with well-separated componentsand different initial setups (e.g., coplanar and non-coplanar orbits).However, the systems we examined had comparable masses. In the presentpaper, the validity of some of the formulae derived previously is testedby numerically integrating the full equations of motion for systems withsmaller mass ratios (from 10-3 to 103, i.e.systems with Jupiter-sized bodies). There is also discussion aboutHD217107 and its planetary companions.
| SB9: The ninth catalogue of spectroscopic binary orbits
The Ninth Catalogue of Spectroscopic Binary Orbits(http://sb9.astro.ulb.ac.be) continues the series of compilations ofspectroscopic orbits carried out over the past 35 years by Batten andcollaborators. As of 2004 May 1st, the new Catalogue holds orbits for2386 systems. Some essential differences between this catalogue and itspredecessors are outlined and three straightforward applications arepresented: (1) completeness assessment: period distribution of SB1s andSB2s; (2) shortest periods across the H-R diagram; (3)period-eccentricity relation.
| Eccentricity evolution in hierarchical triple systems with eccentric outer binaries
We develop a technique for estimating the inner eccentricity inhierarchical triple systems, with the inner orbit being initiallycircular, while the outer one is eccentric. We consider coplanar systemswith well-separated components and comparable masses. The derivation ofshort-period terms is based on an expansion of the rate of change of theRunge-Lenz vector. Then, the short-period terms are combined withsecular terms, obtained by means of canonical perturbation theory. Thevalidity of the theoretical equations is tested by numericalintegrations of the full equations of motion.
| MODEST-2: a summary
This is a summary paper of MODEST-2, a workshop held at the AstronomicalInstitute `Anton Pannekoek' in Amsterdam, 16-17 December 2002. MODEST isa loose collaboration of people interested in MOdelling DEnse STellarsystems, particularly those interested in modelling these systems usingall the available physics (stellar dynamics, stellar evolution,hydrodynamics and the interplay between the three) by defininginterfaces between different codes. In this paper, we summarize: (1) themain advances in this endeavour since MODEST-1; (2) the main sciencegoals which can be and should be addressed by these types ofsimulations; and (3) the most pressing theoretical and modellingadvances that we identified.
| Eccentricity generation in hierarchical triple systems with coplanar and initially circular orbits
We develop a technique for estimating the inner eccentricity inhierarchical triple systems with well-separated components. Weinvestigate systems with initially circular and coplanar orbits andcomparable masses. The technique is based on an expansion of the rate ofchange of the Runge-Lenz vector for calculating short period terms byusing first-order perturbation theory. The combination of the shortperiod terms with terms arising from octupole level secular theoryresults in the derivation of a rather simple formula for theeccentricity of the inner binary. The theoretical results are testedagainst numerical integrations of the full equations of motion.Comparison is also made with other results on the subject.
| Tidal Evolution of the Planetary System around HD 83443
Two planets with an orbital period ratio of approximately 10:1 have beendiscovered around the star HD 83443. The inner and more massive planet,HD 83443b, has the smallest semimajor axis among all currently knownexoplanets. Unlike other short-period exoplanets, it maintains asubstantial orbital eccentricity, e1=0.079+/-0.008, in spiteof efficient tidal damping. This is a consequence of its secularinteractions with HD 83443c, whose orbital eccentricitye2=0.42+/-0.06. Dissipation, associated with tides the starraises in the inner planet, removes energy but not angular momentum fromits orbit, while secular interactions transfer angular momentum but notenergy from the inner to the outer planet's orbit. The outward transferof angular momentum decreases the tidal decay rate of the inner planet'sorbital eccentricity while increasing that of the outer planet. Thealignment of the apsides of the planets' orbits is another consequenceof tidal and secular interactions. In this state the ratio of theirorbital eccentricities, e1/e2, depends on thesecular perturbations the planets exert on each other and on additionalperturbations that enhance the inner planet's precession rate. Tidal androtational distortions of the inner planet along with general relativityprovide the most important of these extra precessional perturbations,each of which acts to reduce e1/e2. Provided theplanets' orbits are coplanar, the observed eccentricity ratio uniquelyrelates sini andC≡(k2/k2J)(R1/RJ)5, where the tidal Love number, k2, andradius, R1, of the inner planet are scaled by their Jovianequivalents.
| Studies of multiple stellar systems - IV. The triple-lined spectroscopic system Gliese 644
We present a radial velocity study of the triple-lined system Gliese 644and derive spectroscopic elements for the inner and outer orbits withperiods of 2.9655 and 627d. We also utilize old visual data, as well asmodern speckle and adaptive optics observations, to derive a newastrometric solution for the outer orbit. These two orbits togetherallow us to derive masses for each of the three components in thesystem: MA=0.410+/-0.028 (6.9 per cent),MBa=0.336+/-0.016 (4.7 per cent), andMBb=0.304+/-0.014 (4.7 per cent)Msolar. We suggestthat the relative inclination of the two orbits is very small. Ourindividual masses and spectroscopic light ratios for the three M starsin the Gliese 644 system provide three points for the mass-luminosityrelation near the bottom of the main sequence, where the relation ispoorly determined. These three points agree well with theoretical modelsfor solar metallicity and an age of 5Gyr. Our radial velocities forGliese 643 and vB 8, two common proper motion companions of Gliese 644,support the interpretation that all five M stars are moving together ina physically bound group. We discuss possible scenarios for theformation and evolution of this configuration, such as the formation ofall five stars in a sequence of fragmentation events leading directly tothe hierarchical configuration now observed, versus formation in a smallN cluster with subsequent dynamical evolution into the presenthierarchical configuration.
| Two Substellar Companions Orbiting HD 168443
Precise Doppler measurements during 4.4 yr from the Keck/HIRESspectrometer reveal two superimposed Keplerian velocity variations forHD 168443 (G6 IV). A simultaneous orbital fit to both companions yieldscompanion masses of Msini=7.7 and 17.2 MJUP, orbital periodsof P=58 days and 4.8 yr, semimajor axes of a=0.29 and 2.9 AU, andeccentricities of e=0.53 and 0.20. An upper limit to the mass of theouter companion of 42 MJUP is derived from the lack ofastrometric wobble. The outer companion was not detected with Keckadaptive optics in the near-IR. Dynamical simulations show that thesystem is remarkably stable for all possible masses of both companions.The two orbiting companions have masses that are probably near andslightly above the upper end of the observed mass distribution of``planets'' at 10 MJUP. Formation in a protoplanetary diskseems plausible. But these objects present a puzzle about theirformation and dynamical history, as well as about their possible kinshipwith planetary systems and triple-star systems. Based on observationsobtained at the W. M. Keck Observatory, which is operated jointly by theUniversity of California and the California Institute of Technology.
| Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Studies of multiple stellar systems - III. Modulation of orbital elements in the triple-lined system HD 109648
The triple-lined spectroscopic triple system HD 109648 has one of theshortest periods known for the outer orbit in a late-type triple,120.5d, and the ratio between the periods of the outer and the innerorbits is small, 22:1. With such extreme values, this system should showorbital element variations over a time-scale of about a decade. We havemonitored the radial velocities of HD 109648 with the CfA DigitalSpeedometers for 8yr, and have found evidence for modulation of someorbital elements. While we see no definite evidence for modulation ofthe inner binary eccentricity, we clearly observe variations in theinner and the outer longitudes of periastron, and in the radial velocityamplitudes of the three components. The observational results, combinedwith numerical simulations, allow us to put constraints on theorientation of the orbits.
| Secular Evolution of Hierarchical Triple Star Systems
We derive octupole-level secular perturbation equations for hierarchicaltriple systems, using classical Hamiltonian perturbation techniques. Ourequations describe the secular evolution of the orbital eccentricitiesand inclinations over timescales that are long compared to the orbitalperiods. By extending previous work done to leading (quadrupole) orderto octupole level (i.e., including terms of order α3,where α≡a1/a2<1 is the ratio ofsemimajor axes), we obtain expressions that are applicable to a muchwider range of parameters. In particular, our results can be applied tohigh-inclination as well as coplanar systems, and our expressions arevalid for almost all mass ratios for which the system is in a stablehierarchical configuration. In contrast, the standard quadrupole-leveltheory of Kozai gives a vanishing result in the limit of zero relativeinclination. The classical planetary perturbation theory, while valid toall orders in α, applies only to orbits of low-mass objectsorbiting a common central mass, with low eccentricities and low relativeinclinations. For triple systems containing a close inner binary, wealso discuss the possible interaction between the classical Newtonianperturbations and the general relativistic precession of the innerorbit. In some cases we show that this interaction can lead toresonances and a significant increase in the maximum amplitude ofeccentricity perturbations. We establish the validity of our analyticexpressions by providing detailed comparisons with the results of directnumerical integrations of the three-body problem obtained for a largenumber of representative cases. In addition, we show that ourexpressions reduce correctly to previously published analytic resultsobtained in various limiting regimes. We also discuss applications ofthe theory in the context of several observed triple systems of currentinterest, including the millisecond pulsar PSR B1620-26 in M4, the giantplanet in 16 Cygni, and the protostellar binary TMR-1.
| The Cessation of Eclipses in SS Lacertae: The Mystery Solved
The 14.4 day period eclipsing binary SS Lacertae in the open cluster NGC7209 is unusual in that the eclipses stopped completely about the middleof this century, giving rise to considerable speculation as to thecause. Disruption of the binary through a collision with another memberof the cluster and, more likely, gravitational perturbations from athird star in the system have been proposed to explain the phenomenon.We present here the results of our intensive radial velocity monitoringof the object, which show clearly that there is indeed a third star inthe system in a slightly eccentric orbit with a period of about 679days. We also reanalyze the historical light curves of SS Lac todetermine the properties of the system early in the century. We discussthe implications of our findings in terms of changes in the inclinationangle of the close pair. An analysis of available times of eclipse forSS Lac together with the new velocity information has also revealedapsidal motion in the system, ω=0.0137d cycle-1,corresponding to an apsidal period of about 1000 yr. We argue that thethird star is probably responsible for this effect also. Some of theobservations reported here were obtained with the Multiple MirrorTelescope, a joint facility of the Smithsonian Institution and theUniversity of Arizona.
| The nature of some doubtful open clusters as revealed by HIPPARCOS
We discuss the nature of some galactic open clusters by using propermotions and parallaxes from the Hipparcos and ACT catalogues. We showthat the clusters Collinder 399, Upgren 1, NGC 1252 and Melotte 227 donot exist. Collinder 132 is found to be mainly composed out of membersof an OB association, but there may be a star cluster present in thisarea too. Roeser & Bastian (1994) proposed that NGC 2451 consists oftwo star clusters. We show that NGC 2451 A definitively does exist, NGC2451 B may exist. A star cluster may also be present in the area ofRoslund 5. The Hipparcos data finally confirm the reality of Collinder135.
| Correlation of the HIPPARCOS and Allegheny Observatory Parallax Catalogs
No significant difference is found between the systems of the Hipparcosand Allegheny Observatory MAP parallax catalogs. The correlation of theparallaxes of 63 stars common to both programs is 0.9995 +/- 0.0001,with an average standard deviation of the difference of 0.0023". Whilethere is no indication of systematic difference in the two programs, ourstudy suggests that the formal errors in one or both catalogs aresomewhat underestimated.
| The Equilibrium Tide Model for Tidal Friction
We derive from first principles the equations governing (a) thequadrupole tensor of a star distorted both by rotation and by thepresence of a companion in a possibly eccentric orbit; (b) a functionalform for the dissipative force of tidal friction, based on the conceptthat the rate of energy loss from a time-dependent tide should be apositive-definite function of the rate of change of the quadrupoletensor as seen in the frame that rotates with the star; and (c) theequations governing the rates of change of the magnitude and thedirection of the stellar rotation, the orbital period and eccentricity,based on the concept of the Laplace-Runge-Lenz vector. Our analysisleads relatively simply to a closed set of equations, valid forarbitrary inclination of the stellar spin to the orbit. The results areequivalent to classical results based on the rather less clear principlethat the tidal bulge lags behind the line of centers by some timedetermined by the rate of dissipation. Our analysis gives the effectivelag time as a function of the dissipation rate and the quadrupolemoment. We discuss briefly some possible applications of theformulation.
| The membership of Upgren One
Upgren One is a group of seven F stars which has been proposed as theremnant of a nearby old open duster. We have monitored the radialvelocities of these stars with the CfA digital speedometers. Two of thestars have velocities which are clearly inconsistent with physicalassociation with the other five stars. Those five include a long-periodbinary and an unusual triple system. The velocity dispersion of the fivestars is too large to be bound under reasonable assumptions about thetotal mass.
| The hierarchical triple system HD 109648
We present observations of the hierarchical triple-lined spectroscopictriple system HD 109648. Using an extended version of a new 2Dcross-correlation technique, TODCOR, we derive radial velocitiesindependently for each component of the system. From a simultaneousorbital solution for hierarchical triple systems, we determine orbitalelements for the inner and outer orbits. With a very short outer orbitalperiod, and a small outer-to-inner period ratio, HD 109648 is one of thebest candidates in which to observe evolution in the orbital elements ofa hierarchical triple system.
| Photometry of astrometric reference stars
UBVRI, DDO, and uvby, H-beta photometry of astrometric reference starsis presented. Spectral types and luminosity classifications made fromthe colors are used to determine their spectroscopic parallaxes. In thispaper, colors for 309 stars in 25 regions are given, and classificationsfor 210 stars have been made. These stars form reference frames in theAllegheny Observatory Multichannel Astrometric Photometer astrometricprogram, and in the Praesepe cluster reduced by Russell (1976). It isfound that the present photometric spectral types are reliable to within2.5 spectral subclasses.
| Seven colour photoelectric photometry of the open cluster an (Upgren).
Not Available
| A study of Upgren 1
Upgren and Rubin (1965) have suggested that a small group of bright Fstars, in the direction of the galactic north pole, may be the remnantof an old cluster. The multichannel astrometric photometer (MAP) hasbeen used to determine the parallaxes of six of the candidate stars withan average precision of 1.1 thousandths of an arcsecond (1.1 mas). Thederived distances are, as suggested, similar, and an unusual spacedensity of F stars seems indicated. However, the derived spacevelocities indicate that the proposed cluster is composed of members oftwo dynamically different groups.
| Kinematics and properties of F stars near the North Galactic Pole. II - The isothermal disc
Radial velocities are given for about 550 photometrically-identifieddisk-population F stars lying within 15 deg of the North Galactic Pole.The overall radial and z-velocity distributions are found to be closelyGaussian, with corrected rms and mean z velocities of 11.3 + or - 0.6and -9.5 + or - 0.5 km/s, respectively. The isothermal kinematics of thepopulation are reflected in the constant velocity dispersion to a zdistance of 400 pc. No systematic variation of either the velocitydispersion or the stellar age with the metallicity-sensitive Stromgrendelta m1 index is noted over a range of ages up to 5 Gyr.
| Spectrophotometry of the F-Stars Members of the UPGREN-1 Group
Not Available
| UPGREN1 - an Old Cluster Near the End of its Life
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1982PASP...94..229U&db_key=AST
| Further Studies of A-Stars and F-Stars in the Region of the North Galactic Pole - Part Four - a Catalogue of Uvbyr Photometry and Derived Quantities
Not Available
| Further Studies of A-Stars and F-Stars in the Region of the North Galactic Pole - Part Three - a Catalogue of Star Names and Positions
Not Available
| A catalogue of stellar spectrophotometric data
A list of 378 sets of stellar energy distributions for 356 stars basedon photoelectric spectrophotometry is presented. Data from eight sourceshave been transformed to the Hayes-Latham calibration of Alpha Lyrae.The procedure follows that of Breger (1976) and the present list extendsprevious data, especially for stars of earliest and intermediatespectral types.
| Studies of A and F stars in the region of the North galactic pole-II. uvby β photometry
Not Available
| Studies of A and F stars in the region of the North galactic pole-I. Radial velocities and MK Classifications
Not Available
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Canes Venatici |
| Right ascension: | 12h35m59.92s |
| Declination: | +36°15'28.2" |
| Apparent magnitude: | 8.713 |
| Distance: | 226.757 parsecs |
| Proper motion RA: | -10 |
| Proper motion Dec: | -31.5 |
| B-T magnitude: | 9.288 |
| V-T magnitude: | 8.761 |
Catalogs and designations:
|
