Adaptive Optics Photometry and Astrometry of Binary Stars. II. A Multiplicity Survey of B Stars

Roberts, Lewis C.; Turner, N.; Brummelaar, Theo A. ten

doi:10.1086/510335

Cited by 217 publications

(31 citation statements)

References 53 publications

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“…The object is either a field object with substantial proper motion or an artifact. These have been seen before in AEOS data, but usually with a much higher dynamic range (Roberts, Turner, & ten Brummelaar 2007). It is possible to estimate the companion spectral type assuming it was at the same distance as the primary and on the main sequence using the absolute magnitudes of the MK classification in Cox (2000).…”

Section: Newly Discovered Componentsmentioning

confidence: 57%

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: Newly Discovered Componentsmentioning

confidence: 57%

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 companions to γ Peg and β Cep are both very faint and the contamination of the primary spectrum can be neglected (Roberts et al 2007;Schnerr et al 2006). In the case of π 4 Ori (Luyten 1936), the lack of information about the secondary forced us to treat it as a single star (Gies & Lambert 1992 classify this system as B2 III + B2 IV, but no details are given).…”

Section: Program Stars and Observational Materialsmentioning

confidence: 99%

The neon content of nearby B-type stars and its implications for the solar model problem

Morel

Butler

2008

A&A

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The recent downward revision of the solar photospheric abundances now leads to severe inconsistencies between the theoretical predictions for the internal structure of the Sun and the results of helioseismology. There have been claims that the solar neon abundance may be underestimated and that an increase in this poorly-known quantity could alleviate (or even completely solve) this problem. Early-type stars in the solar neighbourhood are well-suited to testing this hypothesis because they are the only stellar objects whose absolute neon abundance can be derived from the direct analysis of photospheric lines. Here we present a fully homogeneous NLTE abundance study of the optical Ne i and Ne ii lines in a sample of 18 nearby, early B-type stars, which suggests log (Ne) = 7.97 ± 0.07 dex (on the scale in which log [H] = 12) for the present-day neon abundance of the local interstellar medium (ISM). Chemical evolution models of the Galaxy only predict a very small enrichment of the nearby interstellar gas in neon over the past 4.6 Gyr, implying that our estimate should be representative of the Sun at birth. Although higher by about 35% than the new recommended solar abundance, such a value appears insufficient by itself to restore the past agreement between the solar models and the helioseismological constraints.

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“…They advocated an eccentric orbit and mass transfer resulting in a release of a new shell during periastron passages, but the gaps in their RV curve do not allow one to conclude that the orbit has a high eccentricity. Finally, using the technique of adaptive optics photometry and astrometry, Roberts et al (2007) report discovery of a new companion to BU Tau at a separation of 4. 66 with a spectral type M5.…”

Section: Introductionmentioning

confidence: 99%

Properties and nature of Be stars

Nemravová¹,

Harmanec²,

Kubát

et al. 2010

A&A

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Radial-velocity variations of the Hα emission measured on the steep wings of the Hα line, prewhitened for the long-time changes, vary periodically with a period of 218. d 025 ±0. d 022, confirming the suspected binary nature of the bright Be star BU Tau, a member of the Pleiades cluster. The orbit seems to have a high eccentricity over 0.7, but we also briefly discuss the possibility that the true orbit is circular and that the eccentricity is spurious owing to the phase-dependent effects of the circumstellar matter. The projected angular separation of the spectroscopic orbit is large enough to allow the detection of the binary with large optical interferometers, provided the magnitude difference primary − secondary is not too large. Since our data cover the onset of a new shell phase up to development of a metallic shell spectrum, we also briefly discuss the recent long-term changes. We confirm the formation of a new envelope, coexisting with the previous one, at the onset of the new shell phase. We find that the full width at half maximum of the Hα profile has been decreasing with time for both envelopes. In this connection, we briefly discuss Hirata's hypothesis of precessing gaseous disk and possible alternative scenarios of the observed long-term changes.

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Adaptive Optics Photometry and Astrometry of Binary Stars. II. A Multiplicity Survey of B Stars

Cited by 217 publications

References 53 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

The neon content of nearby B-type stars and its implications for the solar model problem

Properties and nature of Be stars

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