Photometric parallaxes of Southern high proper motion stars. I.

Costa, E.; Méndez, René A.

doi:10.1051/0004-6361:20030166

Cited by 6 publications

(1 citation statement)

References 14 publications

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“…Again, "slow movers" seem to be badly represented in the sample of stars with a known parallax. From the statistics of nearby stars, it is estimated that we have not recognized over 30% of stars within 10 pc and over 60% within 25 pc (Henry et al 2002;Costa & Méndez 2003). However, most (if not all) missing stars are faint, extremely low-mass dwarfs.…”

Section: The Completeness Of Our Searchmentioning

confidence: 93%

Simulating observable comets

Dybczyński

2006

A&A

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Context. This is the third of a series of papers on simulating the mechanisms acting currently on the Oort cloud and producing the observed long-period comets. Aims. In this paper we investigate the influence of current stellar perturbers on the Oort cloud of comets under the simultaneous galactic disk tide. We also analyse the past motion of the observed long-period comets under the same dynamical model to verify the widely used definition of dynamically new comets. Methods. The action of nearby stars and the galactic disk tide on the Oort cloud was simulated. The original orbital elements of all 386 longperiod comets of quality classes 1 and 2 were calculated, and their motion was followed numerically for one orbital revolution into the past, down to the previous perihelion. We also simulated the output of the close future pass of GJ 710 through the Oort cloud. Results. The simulated flux of the observable comets resulting from the current stellar and galactic perturbations, as well as the distribution of perihelion direction, was obtained. The same data are presented for the future passage of GJ 710. A detailed description is given of the past evolution of aphelion and perihelion distances of the observed long-period comets. Conclusions. We obtained no fingerprints of the stellar perturbations in the simulated flux and its directional structure. The mechanisms producing observable comets are highly dominated by galactic disk tide because all current stellar perturbers are too weak. Also the effect of the close passage of the star GJ 710 is very difficult to recognise on the background of the Galactic-driven observable comets. For the observed comets we found only 45 to be really dynamically "new" according to our definition based on the previous perihelion distance value.

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Section: The Completeness Of Our Searchmentioning

confidence: 93%

Simulating observable comets

Dybczyński

2006

A&A

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The Solar Neighborhood. XVI. Parallaxes from CTIOPI: Final Results from the 1.5 m Telescope Program

Costa

Méndez

Jao

et al. 2006

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Trigonometric parallaxes, proper motions and V J (RI) KC photometry are given for 25 stars (of which one is a zeroparallax control field) targeted by the Cerro Tololo Inter-American Observatory Parallax Investigation (CTIOPI), a widely scoped program aimed at discovering and characterizing nearby stars. The trigonometric parallaxes and proper motions presented are the last that were obtained with the CTIO 1.5 m telescope, which targeted the fainter subset of the CTIOPI input list. First trigonometric parallaxes are given for 22 systems, of which one is within 10 pc (DENIS 0255À4700), and 10 of which are between 10 and 25 pc. At a distance of 4:97 AE 0:10 pc, and with a spectral type of L7.5 V, DENIS 0255À4700 is now the closest known L dwarf. In addition, with M V ¼ 24:44, it is the faintest dwarf with a measured absolute visual magnitude. We present preliminary trigonometric parallaxes for five additional systems worthy of follow-up, and VRIJHK S photometry and photometric distance estimates for four of them. We also give photometry and distance estimates for 21 other promising targets in our input list for which definitive trigonometric parallaxes were not possible; 13 are likely to be closer than 25 pc. We also present color-magnitude and color-color diagrams, which, in combination with theoretical isochrones from the literature, tangential velocities, and M R and M J , have aided to identify the general nature of each of our targets. We have in this way discovered one new (spectroscopically confirmed) subdwarf and two suspected extreme subdwarfs that could be among the most extreme cases of these objects. We have also identified several very low mass stars, a few of which could be brown dwarfs. This concludes the CTIOPI 1.5 m program, from which we have derived a total of 69 trigonometric parallaxes (55 definitive, 6 preliminary, and 8 calibration).

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Meeting the Cool Neighbors. XI. Beyond the NLTT Catalog

2007

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We have combined near-infrared data from the Two Micron All Sky Survey with ancillary optical data to identify previously unrecognized proper-motion stars that have colors and magnitudes consistent with nearby M dwarfs. We present follow-up observations of 392 stars from that sample, including $200 stars discussed here for the first time. Our distance estimates, based primarily on spectroscopic parallaxes, place 123 stars within 20 pc of the Sun. One hundred and seventy-six stars exhibit H emission, and 82 stars have plausible X-ray counterparts from ROSAT observations. The distribution of chromospheric and coronal activity is broadly consistent with data for other nearby late-type stars, with $30 stars having activity levels comparable to Pleiades M dwarfs. We have identified several M dwarfs that are probably wide ( >1000 AU ) companions of F and G stars. We have recomputed the 20 pc luminosity function, adding the 123 new candidates found in the present survey. The revised luminosity function is in closer agreement with the 8 pc data set for stars with M J > 8 but probably remains incomplete at the $20% level.

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Photometric parallaxes of Southern high proper motion stars. I.

Cited by 6 publications

References 14 publications

Simulating observable comets

Simulating observable comets

The Solar Neighborhood. XVI. Parallaxes from CTIOPI: Final Results from the 1.5 m Telescope Program

Meeting the Cool Neighbors. XI. Beyond the NLTT Catalog

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