Physical elements of the eclipsing binary<i>δ</i> Orionis

Mayer, P.; Harmanec, P.; Wolf, M.; Božić, H.; Šlechta, M.

doi:10.1051/0004-6361/200913796

Cited by 14 publications

(41 citation statements)

References 42 publications

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“…We used the program described by Morbey & Brosterhus (1974) to find the values of g 1 , g 2 , K 1 , and K 2 that are listed in Table 2. Our estimate of g 1 is intermediate between those determined by Mayer et al (2010) and Pablo et al (2015), and small differences in systemic velocity are not unexpected given the different methods of radial velocity measurement. Our derived value of =  K 104.6 1.…”

Section: Radial Velocities and Orbital Elementscontrasting

confidence: 77%

“…The STIS UV spectra of δ Ori were obtained during visits on 2014 December 30 and 2015 February 10, which correspond to times near Aa1 radial velocity maximum and minimum, respectively, based upon the ephemeris of Mayer et al (2010). We used the E140M echelle grating that records the UV spectrum over the range 1144-1730 Å with a spectral resolving power of  l l =R 46,000 (Kimble et al 1998;Biretta et al 2015).…”

Section: Spectroscopic Observationsmentioning

confidence: 99%

“…Harvin et al (2002) analyzed the available collection of ultraviolet (UV) spectra from the International Ultraviolet Explorer satellite, and they fit cross-correlation functions (CCF) of the observed spectra with that of a sharp-lined template star to determine a double-lined solution that led to relatively small mass estimates. Mayer et al (2010) presented a study of the light curve and high signal-to-noise ratio (S/N) optical spectra, and they argued that the spectral signature of the Ab component was significant while that from Aa2 was too faint to detect. They suggested that the light and radial velocity curves of the Aa1, Aa2 binary were consistent with the masses expected for their spectral classifications.…”

Section: Introductionmentioning

confidence: 99%

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HST/STIS ULTRAVIOLET SPECTROSCOPY OF THE COMPONENTS OF THE MASSIVE TRIPLE STARδORI A

Richardson

Moffat

Gull

et al. 2015

ApJ

197

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The multiple star system of δ Orionis is one of the closest examples of a system containing a luminous O-type, bright giant star (component Aa1). It is often used as a spectral-type standard and has the highest observed X-ray flux of any hot-star binary. The main component Aa1 is orbited by two lower mass stars, faint Aa2 in a 5.7 day eclipsing binary, and Ab, an astrometric companion with an estimated period of 346 years. Generally the flux from all three stars is recorded in ground-based spectroscopy, and the spectral decomposition of the components has proved difficult. Here we present Hubble Space Telescope/Space Telescope Imaging Spectrograph ultraviolet spectroscopy of δ Ori A that provides us with spatially separated spectra of Aa and Ab for the first time. We measured radial velocities for Aa1 and Ab in two observations made near the velocity extrema of Aa1. We show tentative evidence for the detection of the Aa2 component in cross-correlation functions of the observed and model spectra. We discuss the appearance of the UV spectra of Aa1 and Ab with reference to model spectra. Both stars have similar effective temperatures, but Ab is fainter and is a rapid rotator. The results will help in the interpretation of ground-based spectroscopy and in understanding the physical and evolutionary parameters of these massive stars.

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Section: Radial Velocities and Orbital Elementscontrasting

confidence: 77%

Section: Spectroscopic Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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HST/STIS ULTRAVIOLET SPECTROSCOPY OF THE COMPONENTS OF THE MASSIVE TRIPLE STARδORI A

Richardson

Moffat

Gull

et al. 2015

ApJ

197

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“…Different stellar mass values are given in the literature. Harvin et al (2002) give M p = 10.3 M as average with R p = 11 R and for the secondary star M s = 5.2 M and R s = 4 R , while Mayer et al (2010) suggest values of M p = 25 M with R s = 16−17 R . The primary and secondary stars are separated by 33 R , equivalent to 3 R p .…”

Section: Introductionmentioning

confidence: 97%

The X-ray spectrum ofδOrionis observed by LETGS aboardChandra

Raassen

Pollock

2013

A&A

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Aims. We analyze the high-resolution X-ray spectrum of the supergiant O-star δ Orionis (O9.5II) with line ratios of He-like ions and a thermal plasma model, and we examine its variability. Methods. The O-supergiant δ Ori was observed in the wavelength range 5-175 Å by the X-ray detector HRC-S in combination with the grating LETG aboard Chandra. We studied the He-like ions in combination with the UV-radiation field to determine local plasma temperatures and to establish the distance of the X-ray emitting ions to the stellar surface. We measured individual lines by means of Gaussian profiles, folded through the response matrix, to obtain wavelengths, line fluxes, half widths at half maximum (HWHM) and line shifts to characterize the plasma. We consider multitemperature models in collisional ionization equilibrium (CIE) to determine temperatures, emission measures, and abundances.Results. Analysis of the He-like triplets extended to N vi and C v implies ionization stratification with the hottest plasma to be found within a few stellar radii 3 R * (Mg xi) and the coolest farther out, far beyond the acceleration zone, up to 49 R * (N vi) and 75 R * (C v).The observed temperatures cover a range from about 0.1 to 0.7 keV, i.e., 1-8 MK. The X-ray luminosity (L x ) is ∼1.5 × 10 32 erg/s in the range from 0.07 to 3 keV covered by LETGS. Velocity widths of about 1040 km s −1 have been determined.

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“…The primary component is itself a known eclipsing binary (δ Orionis Aa1-Aa2) which has an orbital period of 5.7 days (Harvey et al, 1987). The primary component is a spectral type O star but it is suspected to have yet another tertiary component of the same spectral type (Mayer et al, 2010;Zasche et al, 2009). Despite the extended astrophysical structure of the primary component, observations of δ Orionis AaAb were attempted because it is one of the stars in the MUSCA science target list which will be discussed in Chapter 8.…”

Section: δ Orionis Aa-abmentioning

confidence: 99%

Phase-Referenced Interferometry and Narrow-Angle Astrometry With Susi

Kok

Ireland

Tuthill

et al. 2013

J. Astron. Instrum.

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This thesis describes the development of an astrometric facility at the Sydney University Stellar Interferometer (SUSI) with an aim to measure at high precision the relative astrometry of bright close binary stars and ultimately to detect the presence of exoplanets within those binary star systems through observations of the systems' perturbed motion. At the core of the facility is a new beam combiner that is phase-referenced to an existing primary beam combiner in the visible wavelength regime. The latter provides post-processed fringe-tracking information to the former for fringe stabilization and coherent integration of pre-recorded stellar fringes using newly developed data reduction software. Interference fringe packets of a binary star are recorded alternately; first the fringe packet of the primary, then the secondary, finally back to the primary again. The measurement of the fringe packet separation is facilitated by an air-filled differential delay line and a network of interferometer-based metrology systems. Characterizations and initial astronomical observations carried out with the dual beam combiner setup demonstrated for the first time the success of the dual-star phase-referencing technique in visible (ă1µm) wavelengths. The current astrometric precision is larger than 100µas while the long term astrometric accuracy is yet to be characterized. In a parallel development, a complementary observing method using only the primary beam combiner is also demonstrated in this thesis. Relative astrometry of binary stars up to "0.8 2 separation with this technique has been demonstrated to have precision of better than 100µas. A simple detection limit analysis based on a list of target binary stars estimates up to two exoplanet detections can be achieved with SUSI if the new astrometric facility attains precision of 10µas while the primary beam combiner operates at its designed peak performance. Finally, one new stellar companion was resolved and a preliminary astrometry for another suspected companion was estimated from the astronomical observation data collected throughout the course of this thesis.

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Physical elements of the eclipsing binaryδ Orionis

Cited by 14 publications

References 42 publications

HST/STIS ULTRAVIOLET SPECTROSCOPY OF THE COMPONENTS OF THE MASSIVE TRIPLE STARδORI A

HST/STIS ULTRAVIOLET SPECTROSCOPY OF THE COMPONENTS OF THE MASSIVE TRIPLE STARδORI A

The X-ray spectrum ofδOrionis observed by LETGS aboardChandra

Phase-Referenced Interferometry and Narrow-Angle Astrometry With Susi

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