Speckle Interferometry at the US Naval Observatory. XII.

Mason, Brian D.; Hartkopf, William I.; Wycoff, G. L.; Holdenried, E. R.

doi:10.1086/508231

Cited by 228 publications

(21 citation statements)

References 34 publications

(21 reference statements)

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“…The astrometry for all but two systems was consistent with the published data. The position angle of HD 137107 (WDS 15232+3017) is inconsistent with the orbit of (Mason et al 2006), though the separation appears to be in agreement. The position angle computed from the orbital elements is 77…”

Section: Resultsmentioning

confidence: 88%

“…′′ 67 (Mason et al 2006) along with a third star at a separation of over an arcminute. Both of the measurements of the AB pair in this paper are off by 180…”

Section: Resultsmentioning

confidence: 99%

“…• from the astrometry computed from the orbit of Mason et al (2006). Looking at the data collected over the last few decades , quadrant ambiguity is a fairly common occurrence.…”

Section: Resultsmentioning

confidence: 99%

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Astrometric and photometric measurements of binary stars with adaptive optics: observations from 2001 to 2006

Roberts

Mason

2017

Monthly Notices of the Royal Astronomical Society

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The adaptive optics system at the 3.6 m AEOS telescope was used to measure the astrometry and differential magnitude in I -band of 56 binary stars in 2002. The astrometric measurements will be of use for future orbital determination, and the photometric measurements will be of use in estimating the spectral types of the component stars. Two candidate companions were detected, but neither is likely to be gravitationally bound. Nine systems had not been observed in over 40 years. Eight of these are shown to share common proper motion, while HD 182352 is shown to be a background star. One of the two components of the HD 114378 (α Com) is shown to be a variable star of unknown type. In addition, 86 stars were unresolved and the full-width half maxima of the images are presented.

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Section: Resultsmentioning

confidence: 88%

“…′′ 67 (Mason et al 2006) along with a third star at a separation of over an arcminute. Both of the measurements of the AB pair in this paper are off by 180…”

Section: Resultsmentioning

confidence: 99%

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Astrometric and photometric measurements of binary stars with adaptive optics: observations from 2001 to 2006

Roberts

Mason

2017

Monthly Notices of the Royal Astronomical Society

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“…1-9, the United States Naval Observatory (USNO) speckle camera (Mason et al 2006) was used on the KPNO 4 m Mayall reflector. The same USNO speckle camera was also used on the CTIO 4 m Blanco telescope from 2006 march 9-13.…”

Section: Observations and Calibrations Of Speckle Interferometrymentioning

confidence: 99%

Cool Subdwarf Investigations. Ii. Multiplicity

Jao

Mason

Hartkopf

et al. 2009

The Astronomical Journal

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Cool subdwarfs of types K and M are the fainter counterparts of cool main-sequence dwarfs that dominate the Galactic population. In this paper, we present the results of an optical speckle survey of 62 confirmed cool subdwarf systems within 60 pc. We have resolved two new companions and confirmed two previously known companions with separations 0. 13-3. 29. After including previously known wide companions and all known spectroscopic binaries, we determine the multiplicity rate of cool subdwarfs to be 26% ± 6%, which is somewhat lower than comparable main-sequence stars that have a multiplicity rate of 37% ± 5%. We find that only 3% of the cool subdwarfs surveyed have companions within 10 AU, 3% have companions between 10 and 100 AU, and 14% have companions beyond 100 AU. The other 6% of cool subdwarfs are spectroscopic binaries. This is very different from K/M dwarfs that have most companions (13%) at separations closer than 10 AU. However, because a search for close binaries among a large sample of nearby cool subdwarfs remains elusive, it is not yet settled whether or not the multiplicity rates are significantly different. Nonetheless, several different observational results and theories pointing to a possible dearth of subdwarf multiples are discussed.

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“…HD 200580: Only recently identified as a visual binary using speckle interferometry (Mason et al 2001). The angular distance of the two stellar components is only 0.13 arcsec.…”

Section: Notes On Data Reductionmentioning

confidence: 99%

Abundances of Na, Mg and Al in nearby metal-poor stars

Gehren

Liang

Shi

et al. 2004

A&A

138

186

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Abstract.To determine the population membership of nearby stars we explore abundance results obtained for the light neutronrich elements 23 Na and 27 Al in a small sample of moderately metal-poor stars. Spectroscopic observations are limited to the solar neighbourhood so that gravities can be determined from H parallaxes, and the results are confronted with those for a separate sample of more metal-poor typical halo stars. Following earlier investigations, the abundances of Na, Mg and Al have been derived from NLTE statistical equilibrium calculations used as input to line profile synthesis. We do not confirm the age gap between thin and thick disk found by Fuhrmann. Instead we find an age boundary between halo and thick disk stars, however, with an absolute value of 14 Gyr that must be considered as preliminary. While the stellar sample is by no means complete, the resulting abundances indicate the necessity to revise current models of chemical evolution and/or stellar nucleosynthesis to allow for an adequate production of neutron-rich species in early stellar generations.

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Speckle Interferometry at the US Naval Observatory. XII.

Cited by 228 publications

References 34 publications

Astrometric and photometric measurements of binary stars with adaptive optics: observations from 2001 to 2006

Astrometric and photometric measurements of binary stars with adaptive optics: observations from 2001 to 2006

Cool Subdwarf Investigations. Ii. Multiplicity

Abundances of Na, Mg and Al in nearby metal-poor stars

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