Contenuti
Immagini
Carica la tua immagine
DSS Images Other Images
Articoli relazionati
Five New Multicomponent Planetary Systems
We report Doppler measurements for six nearby G- and K-typemain-sequence stars that show multiple low-mass companions, at least oneof which has planetary mass. One system has three planets, the fourthtriple-planet system known around a normal star, and another has anextremely low minimum mass of 18 M⊕. HD 128311 (K0 V)has two planets (one previously known) with minimum masses (Msini) of2.18MJ and 3.21MJ and orbital periods of 1.26 and2.54 yr, suggesting a possible 2:1 resonance. For HD 108874 (G5 V), thevelocities reveal two planets (one previously known) having minimummasses and periods of (Msinib=1.36MJ,Pb=1.08 yr) and (Msinic=1.02MJ,Pc=4.4 yr). HD 50499 (G1 V) has a planet with P=6.8 yr andMsini=1.7MJ, and the velocity residuals exhibit a trend of-4.8 m s-1 yr-1, indicating a more distantcompanion with P>10 yr and minimum mass of 2MJ. HD 37124(G4 IV-V) has three planets, one having Msini=0.61MJ andP=154.5 days, as previously known. We find two plausible triple-planetmodels that fit the data, both having a second planet near P=840 days,with the more likely model having its third planet in a 6 yr orbit andthe other one in a 29 day orbit. For HD 190360, we confirm the planethaving P=7.9 yr and Msini=1.5MJ as found by the Geneva team,but we find a distinctly noncircular orbit with e=0.36+/-0.03, renderingthis not an analog of Jupiter as had been reported. Our velocities alsoreveal a second planet with P=17.1 days and Msini=18.1M⊕. HD 217107 (G8 IV) has a previously known ``hotJupiter'' with Msini=1.4MJ and P=7.13 days, and we confirmits high eccentricity, e=0.13. The velocity residuals reveal an outercompanion in an eccentric orbit, having minimum mass ofMsini>2MJ, eccentricity e~0.5, and a period P>8 yr,implying a semimajor axis a>4 AU and providing an opportunity fordirect detection. We have obtained high-precision photometry of five ofthe six planetary host stars with three of the automated telescopes atFairborn Observatory. We can rule out significant brightness variationsin phase with the radial velocities in most cases, thus supportingplanetary reflex motion as the cause of the velocity variations.Transits are ruled out to very shallow limits for HD 217107 and are alsoshown to be unlikely for the prospective inner planets of the HD 37124and HD 108874 systems. HD 128311 is photometrically variable with anamplitude of 0.03 mag and a period of 11.53 days, which is much shorterthan the orbital periods of its two planetary companions. This rotationperiod explains the origin of periodic velocity residuals to thetwo-planet model of this star. All of the planetary systems here wouldbe further constrained with astrometry by the Space InterferometryMission.Based on observations obtained at the W. M. Keck Observatory, which isoperated jointly by the University of California and the CaliforniaInstitute of Technology. Keck time has been granted by both NASA and theUniversity of California.
| 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.
| SANTIAGO 91, a right ascension catalogue of 3387 stars (equinox J2000).
The positions in right ascension of 3387 stars belonging to the Santiago67 Catalogue, observed with the Repsold Meridian Circle at Cerro Calan,National Astronomical Observatory, during the period 1989 to 1994, aregiven. The average mean square error of a position, for the wholeCatalogue, is +/-0.009 s. The mean epoch of the catalogue is 1991.84.
| Evolved GK stars near the sun. I - The old disk population
A sample of nearly two thousand GK giants with intermediate band, (R,I),DDO and Geneva photometry has been assembled. Astrometric data is alsoavailable for most of the stars. The some 800 members of the old diskpopulation in the sample yield accurate luminosities (from two sources),reddening values and chemical abundances from calibrations of thephotometric parameters. Less than one percent of the objects arepeculiar in the sense that the flux distribution is abnormal. Thepeculiarity is signaled by strong CH (and Ba II) and weak CH. The CH+stars are all spectroscopic binaries, probably with white dwarfcompanions, whereas the CH- stars are not. A broad absorption band,centered near 3500 A, is found in the CH+ stars whereas the CH- objectshave a broad emission feature in the same region. The intensity of theseabsorptions and emissions are independent of the intensity of abnormalspectral features. Ten percent of the old disk sample have a heavyelement abundance from one and a half to three times the solar value.The distribution of the heavy element abundances is nearly a normal onewith a peak near solar abundance and ranges three times to one sixthsolar. The distribution of the (U, V) velocities is independent of theheavy element abundance and does not appear to be random. Ten percent ofthe old disk stars show a CN anomaly, equally divided between CN strongand CN weak. Several stars of individual astrometric or astrophysicalimportance are isolated.
| Large and kinematically unbiased samples of G- and K-type stars. IV - Evolved stars of the old disk population
Modified Stromgren and (R,I) photometry, along with DDO and Genevaphotometry, are presented for a complete sample of evolved old-disk Gand K giants in the Bright Star Catalogue. Stars with ages of between1.5 x 10 to the 9th and 10 to the 10th yr are found to have anear-normal distribution of heavy element abundances, centered on anFe/H abundance ratio of -0.1 dex. The old disk clusters NGC 3680 and IC4651 contain red-straggler young-disk giants that are probablycontemporaries of the blue stragglers in the clusters.
| Large and kinematically unbiased samples of G- and K-type stars. II - Observations of evolved stars in the Bright Star sample. III - Evolved young disk stars in the Bright Star sample
Four color and RI observations were obtained for a large sample ofG-type and K-type stars in the Bright Star Catalogue. Data are firstpresented for 110 evolved stars. Photometry of evolved young diskpopulation stars have then been calibrated for luminosity, reddening,and metallicity on the basis of results for members of the Hyades andSirius superclusters. New DDO results are given for 120 stars.
| Radial velocities of southern stars obtained with the photoelectric scanner CORAVEL. III - 790 late-type bright stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&AS...59...15A&db_key=AST
| Narrow-Band and Broad-Band Photometry of Red Stars. III. Southern Giants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJ...161..199E&db_key=AST
| Stellar parallaxes determined photographically at the Cape Observatory (Eighteenth List)
Not Available
|
Sottometti un nuovo articolo
Link relazionati
Sottometti un nuovo link
Membro dei seguenti gruppi:
|
Osservazione e dati astrometrici
| Costellazione: | Cane Maggiore |
| Ascensione retta: | 06h39m42.70s |
| Declinazione: | -30°28'13.0" |
| Magnitudine apparente: | 5.71 |
| Distanza: | 73.855 parsec |
| Moto proprio RA: | -7.5 |
| Moto proprio Dec: | -191.7 |
| B-T magnitude: | 7.173 |
| V-T magnitude: | 5.829 |
Cataloghi e designazioni:
|
INHABITED SKY
