High Angular Resolution Observations of Late‐Type Stars

Prieur, Jean‐Louis; Aristidi, Éric; López, B.; Scardia, M.; Mignard, F.; Carbillet, Marcel

doi:10.1086/338029

Cited by 32 publications

(39 citation statements)

References 21 publications

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“…One of the most convincing pieces of evidence supporting the latter theory is that Mira B's luminosity is much too low, P1 L , versus the estimated $10 L required for a white dwarf. Finally, the star has been suggested to be something in between the previous two options: a variable star with a 14 yr period (Prieur et al 2002). The nature of the companion should not play much of a role in our analysis, because the separation between Mira A and Mira B is so large that it is likely that the companion has little influence on the system in the range we consider.…”

Section: Introductionmentioning

confidence: 98%

Asymmetries and Outflows in the Circumstellar Dust of Mira A

Chandler

Tatebe

Wishnow

et al. 2007

ApJ

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Asymmetries and motions in the dust shell surrounding Mira A (o Ceti) are reported. Measurements were taken with the UC Berkeley Infrared Spatial Interferometer (ISI), a three-element interferometer operating at 11.15 m. At the time of these observations, it was in a linear, east-west configuration with a maximum baseline of 12 m and thus had a resolution of better than 100 mas. Three years of data (2003)(2004)(2005) are presented and permit observation of the movement of dust shells over time. Fits are made to the visibility and closure-phase curves, which are then used to create one-dimensional profiles of the dust shells. Asymmetries in the circumstellar dust have been observed, and several possible explanations for these asymmetries are explored.

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Section: Introductionmentioning

confidence: 98%

Asymmetries and Outflows in the Circumstellar Dust of Mira A

Chandler

Tatebe

Wishnow

et al. 2007

ApJ

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“…Mira AB is a "symbioticlike" or "weakly symbiotic" system at a distance of 107 pc (Knapp et al 2003). According to the preliminary orbit of Prieur et al (2002), the orbital period is 497.9 years and the inclination is 112.…”

Section: Introductionmentioning

confidence: 99%

Evidence for the White Dwarf Nature of Mira B

Sokoloski

Bildsten

2010

ApJ

229

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The nature of the accreting companion to Mira-the prototypical pulsating asymptotic giant branch star-has been a matter of debate for more than 25 years. Here, we use a quantitative analysis of the rapid optical brightness variations from this companion, Mira B, which we observed with the Nickel Telescope at Lick Observatory, to show that it is a white dwarf (WD). The amplitude of aperiodic optical variations on timescales of minutes to tens of minutes (≈0.2 mag) is consistent with that of accreting WDs in cataclysmic variables on these same timescales. It is significantly greater than that expected from an accreting main-sequence star. With Mira B identified as a WD, its ultraviolet (UV) and optical luminosities, along with constraints on the WD effective temperature from the UV, indicate that it accretes at ∼10 −10 M yr −1 . This accretion rate is lower than that predicted by Bondi-Hoyle theory. The accretion rate is high enough, however, to explain the weak X-ray emission, since the accretion-disk boundary layer around a low-mass WD accreting at this rate is likely to be optically thick and therefore to emit primarily in the far or extreme UV. Furthermore, the finding that Mira B is a WD means that it has experienced, and will continue to experience, nova explosions, roughly every 10 6 years. It also highlights the similarity between Mira AB and other jet-producing symbiotic binaries such as R Aquarii, CH Cygni, and MWC 560, and therefore raises the possibility that Mira B launched the recently discovered bipolar streams from this system.

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“…o Ceti and its companion Mira B are separated by only ∼0.5 ′′ (Karovska et al 1997), corresponding to ∼46 AU. The orbital elements of the system, originally determined by Baize (1980) lead to an orbital period of P∼400 yr. A more recent revision by Prieur et al (2002) leads to an increase of the estimation of the period by nearly 100 yr (the new estimated period being P∼498 yr).…”

Section: The Authorsmentioning

confidence: 99%

“…Baize (1980) proposed a first estimation of the orbital elements of the system which have been recalculated more recently by Prieur et al (2002), in the light of new speckle observations of o Ceti. Nevertheless, and as pointed out by the latter authors, since even the sum of the masses is unknown and the trajectory is still poorly sampled, the orbital elements of the binary system can not be tightly constrained.…”

Section: Flare Propagation and Velocity Driftmentioning

confidence: 99%

“…Such an analysis will be presented in a subsequent paper. Bearing in mind this latter warning and that a wide range of parameters is possible in terms of orbital parameters, adopting the most recent orbital period determination of Prieur et al (2002;P∼500 yr), a total mass of the system of 3.0 M⊙, a typical Mira mass of 1.0 M⊙ for o Ceti, a deprojected separation of ∼85.6 AU between the 2 stars would lead to an intrinsic acceleration of ∼0.05 km s −1 yr −1 around the barycentre of the system for o Ceti. Note that the total mass of 3.0 M⊙ adopted here would not necessarily preclude Mira B from being a white dwarf, as the 2.0 M⊙ represents the overall counterpart mass of the binary system, corresponding to Mira B and the surrounding material of the binary system.…”

Section: Flare Propagation and Velocity Driftmentioning

confidence: 99%

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Recurring OH Flares towards o Ceti: I. location and structure of the 1990s’ and 2010s’ events

Etoka

Gérard

Richards

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present the analysis of the onset of the new 2010s' OH flaring event detected in the OH ground-state main line at 1665 MHz towards o Ceti and compare its characteristics with those of the 1990s' flaring event. This is based on a series of complementary single-dish and interferometric observations both in OH and H 2 O obtained with the Nançay Radio telescope (NRT), the Medicina and Effelsberg Telescopes, the European VLBI Network (EVN), and (e)Multi-Element Radio Linked Interferometer Network ((e)MERLIN). We compare the overall characteristics of o Ceti's flaring events with those which have been observed towards other thin-shell Miras, and explore the implication of these events with respect to the standard OH circumstellar-envelope model. The role of binarity in the specific characteristics of o Ceti's flaring events is also investigated. The flaring regions are found to be less than ∼400±40 mas (i.e., ≤ 40 ± 4 AU) either side of o Ceti, with seemingly no preferential location with respect to the direction to the companion Mira B. Contrary to the usual expectation that the OH maser zone is located outside the H 2 O maser zone, the coincidence of the H 2 O and OH maser velocities suggests that both emissions arise at similar distances from the star. The OH flaring characteristics of Mira are similar to those observed in various Mira variables before, supporting the earlier results that the regions where the transient OH maser emission occurs are different from the standard OH maser zone.

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High Angular Resolution Observations of Late‐Type Stars

Cited by 32 publications

References 21 publications

Asymmetries and Outflows in the Circumstellar Dust of Mira A

Asymmetries and Outflows in the Circumstellar Dust of Mira A

Evidence for the White Dwarf Nature of Mira B

Recurring OH Flares towards o Ceti: I. location and structure of the 1990s’ and 2010s’ events

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