VLBI astrometric identification of the radio emitting region in Algol and determination of the orientation of the close binary

Lestrade, J. F.; Phillips, R. B.; Hodges, Mark; Preston, R. A.

doi:10.1086/172798

Cited by 59 publications

(73 citation statements)

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“…The Algol system is an eclipsing binary (with a period of 2.9 days, consisting of B8 V primary and K0 IV secondary) and a distant companion with an orbital period of 1.86 yr. VLBI astrometry by Lestrade et al (1993) revealed that the radio emission originates from the K0 subgiant and traced the orbital motion of eclipsing binary, indicating that the orbit of the binary is nearly orthogonal to that of the tertiary companion. Observations of another hierarchical triple (Algol-like) system, UX Ari, by Peterson et al (2011) detected the acceleration of the tight binary caused by the tertiary star.…”

Section: Radio Starsmentioning

confidence: 99%

Microarcsecond Radio Astrometry

Reid

Honma

2014

Annu. Rev. Astron. Astrophys.

181

191

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Astrometry provides the foundation for astrophysics. Accurate positions are required for the association of sources detected at different times or wavelengths, and distances are essential to estimate the size, luminosity, mass, and ages of most objects. Very Long Baseline Interferometry at radio wavelengths, with diffraction-limited imaging at sub-milliarcsec resolution, has long held the promise of micro-arcsecond astrometry. However, only in the past decade has this been routinely achieved. Currently, parallaxes for sources across the Milky Way are being measured with ∼ 10 µas accuracy and proper motions of galaxies are being determined with accuracies of ∼ 1 µas y −1 . The astrophysical applications of these measurements cover many fields, including star formation, evolved stars, stellar and super-massive black holes, Galactic structure, the history and fate of the Local Group, the Hubble constant, and tests of general relativity. This review summarizes the methods used and the astrophysical applications of micro-arcsecond radio astrometry.

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Section: Radio Starsmentioning

confidence: 99%

Microarcsecond Radio Astrometry

Reid

Honma

2014

Annu. Rev. Astron. Astrophys.

181

191

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“…(The masses are given in solar mass, the period in days, and the angular orbital elements in degrees.) The non-arbitrary parameters are taken from Söderhjelm (1980), Lestrade et al (1993) for Algol, and from Drechsel et al (1994) …”

Section: Comparison With Other Analytical and Numerical Calculationsmentioning

confidence: 99%

On the detectability of long period perturbations in close hierarchical triple stellar systems

Borkovits

Érdi

Forgács‐Dajka

et al. 2003

A&A

104

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Abstract.We study the possibility of the detection of the low amplitude long (P ) period perturbative effect of a distant third companion on the motion of a close binary. We give a new, more accurate analytical formula for this kind of perturbation affecting the moments of the times of minima in eclipsing binaries. The accuracy of this formula is tested by numerical integrations carried out for several initial configurations. We also describe a numerical method based on a non-linear Levenberg-Marquardt algorithm which makes it possible to separate this dynamical effect from the pure geometrical light-time effect in the eclipsing O−C diagram. The capabilities of this new method are demonstrated by the analysis of numerically simulated O−Cs for test systems having physical parameters very similar to Algol and IU Aur. The results show that the above mentioned effect would be detectable in these systems nowadays, observing almost each minima events in a 1-2 year-long interval.

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“…Unambiguously known mutual inclinations of triple systems. The value for Algol is determined using the measurement precisions and values of Pan et al (1993) for all but the A-B nodal position angle of 52 ± 5 degrees from Lestrade et al (1993 (Tokovinin 1997) for which both visual orbits were known, but the ascending nodes had 180 degree ambiguities. To correct for this lack of information, for each system they included both possible mutual inclinations in a combined cumulative distribution (this distribution is referred to as ST).…”

Section: Mutual Inclinationmentioning

confidence: 99%

PHASES differential astrometry and the mutual inclination of the V819 Herculis triple star system

Muterspaugh

Lane

Konacki

et al. 2006

A&A

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V819Herculis is a well-studied triple star system consisting of a "wide" pair with 5.5 year period, one component of which is a 2.2-day period eclipsing single-line spectroscopic binary. Differential astrometry measurements from the Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) are presented and used to determine a relative inclination between the short-and long-period orbits of 23.6 ± 4.9 degrees. This represents only the sixth unambiguous determination of the mutual inclination of orbits in a hierarchical triple system. This result is combined with those for the other five systems for analysis of the observed distribution of mutual inclinations in nearby triple systems. It is found that this distribution is different than that which one would expect from random orientations with statistical significance at the 94% level; implications for studying the spatial distribution of angular momentum in star forming regions is discussed.

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VLBI astrometric identification of the radio emitting region in Algol and determination of the orientation of the close binary

Cited by 59 publications

References 0 publications

Microarcsecond Radio Astrometry

Microarcsecond Radio Astrometry

On the detectability of long period perturbations in close hierarchical triple stellar systems

PHASES differential astrometry and the mutual inclination of the V819 Herculis triple star system

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