IUE observations of circumstellar emission from the late type variable R Aquarii /M7 + pec/

Hobbs, R. W.; Michalitsianos, A. G.; Kafatos, Menas

doi:10.1086/157895

Cited by 28 publications

(12 citation statements)

References 3 publications

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“…According to Bondi‐‐Hoyle theory, even in a wide binary system a white dwarf can accrete as much as ∼1 per cent of the stellar wind of the giant (Livio 1988, and references therein), which in the case of RX Pup is just what is needed. The observed quiescent luminosities of the compact components of the Mira AB (∼2 L; Karovska et al 1997) 2 and R Aqr (a few L; Michalitsianos, Kafatos & Hobbs 1980) spatially resolved wind‐accreting binary systems agree with the values predicted by the accretion theory. The component separation of Mira AB, a ∼ 70 au (Karovska et al 1997), is comparable to that expected for RX Pup, while the quiescent L h in RX Pup is a factor of ∼100 higher than that of Mira B, in good agreement with more or less the same order‐of‐magnitude difference in the mass‐loss rates of the Mira in RX Pup ( M˙ c ∼4×10 −6 M yr −1 ; Section 3.2.4) and that of Mira A ( M˙ c ∼10 −7 M yr −1 ; Reimers & Cassatella 1985).…”

Section: Discussionsupporting

confidence: 78%

The symbiotic binary system RX Puppis: a possible recurrent nova with a Mira companion

Mikołajewska

Brandi

Hack

et al. 1999

Monthly Notices of the Royal Astronomical Society

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A B S T R A C TWe present an analysis of photometric and spectroscopic observations of the symbiotic binary system RX Pup with the aim of developing a reliable binary model for the system and identifying mechanisms responsible for its spectacular activity. The binary is composed of a long-period Mira variable surrounded by a thick dust shell and a hot ,0:8 M ( white dwarf companion. The hot component produces practically all activity observed in the UV, optical and radio range, while variable obscuration of the Mira by circumstellar dust is responsible for long-term changes in the near-infrared magnitudes. The observations show that RX Pup underwent a nova-like eruption during the last three decades. The hot component contracted in radius at roughly constant luminosity from 1975 to 1986, and was the source of a strong stellar wind, which prevented it from accreting material lost in the Mira wind. Around 1988/9 the hot component turned over in the Hertzsprung±Russell (HR) diagram and by 1991 its luminosity had faded by a factor of ,30 with respect to the maximum plateau value and the hot wind had practically ceased. By 1995 the nova remnant started to accrete material from the Mira wind, as indicated by a general increase in intensity of the optical continuum and H i emission. The quiescent spectrum resembles the quiescent spectra of symbiotic recurrent novae, and its intensity indicates that the hot component must accrete as much as ,1 per cent of the Mira wind, which is more or less the amount predicted by Bondi±Hoyle theory. The earliest observational records from the 1890s suggest that another nova-like eruption of RX Pup occurred around 1894.

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Section: Discussionsupporting

confidence: 78%

The symbiotic binary system RX Puppis: a possible recurrent nova with a Mira companion

Mikołajewska

Brandi

Hack

et al. 1999

Monthly Notices of the Royal Astronomical Society

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“…An additional motivation for targeting R Aqr is that it is part of a symbiotic binary system, with the orbit of the hot companion lying within the cool giant's circumstellar envelope (e.g., Spergel et al 1983;Hollis et al 1986). It has been suggested that the primary source of the H i emission detected from the weakly symbiotic AGB star o Ceti could be H 2 photodissociated by its hot companion Gérard & Le Bertre 2003); hence, it is of interest Michalitsianos et al (1980;R Aqr) or from Table 3 of Knapp et al (1998;all other stars). References for the remaining quantities are provided in x 4.…”

Section: Sample Selectionmentioning

confidence: 99%

“…Although R Aqr is surrounded by extensive nebulosity (extending to at least 2 0 ; e.g., Wallerstein & Greenstein 1980;Hollis et al 1985), the current mass-loss rate of the star is rather low. Based on ultraviolet spectroscopy and radio continuum observations, respectively, both Michalitsianos et al (1980) and Spergel et al ( 1983) estimatedṀ $ 6 ; 10 À8 M yr À1 . However, these determinations may underestimate the actual massloss rate by as much as an order of magnitude, depending on the fraction of the wind that is ionized (e.g., Dougherty et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Very Large Array Observations of Hiin the Circumstellar Envelopes of Asymptotic Giant Branch Stars

Matthews

Reid

2007

Astron J

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We have used the Very Large Array to search for neutral atomic hydrogen (H i) in the circumstellar envelopes of five asymptotic giant branch stars. We have detected H i 21 cm emission coincident in both position and velocity with the S-type semiregular variable star RS Cnc. The emission comprises a compact, slightly elongated feature centered on the star with a mean diameter of $82 00 (1:5 ; 10 17 cm), plus an additional filament extending $6 0 to the northwest. If this filament is associated with RS Cnc, it would imply that a portion of its mass loss is highly asymmetric. We estimate M H i % 1:5 ; 10 À3 M and a mass-loss rateṀ % 1:7 ; 10 À7 M yr À1 . Toward three other stars (IRC+10216, EP Aqr, R Cas) we have detected arcminute-scale H i emission features at velocities consistent with the circumstellar envelopes, but spatially offset from the stellar positions. Toward R Cas, the emission is weak but peaks at the stellar systemic velocity and overlaps with the location of its circumstellar dust shell and thus is probably related to the star. In the case of IRC+10216, we were unable to confirm the detection of H i in absorption against the cosmic background previously reported by Le Bertre & Gérard. However, we detect arcs of emission at projected distances of r $ 14 0 Y18 0 ($2 ; 10 18 cm) to the northwest of the star. The large separation of the emission from the star is plausible, given its advanced evolutionary status, although it is unclear if the asymmetric distribution and complex velocity structure are consistent with a circumstellar origin. For EP Aqr, the detected H i emission comprises multiple clumps redward of the systemic velocity, but we are unable to determine unambiguously whether the emission arises from the circumstellar envelope or from interstellar clouds along the line of sight. Regardless of the adopted distance for the H i clumps, their inferred H i masses are at least an order of magnitude smaller than their individual gravitational binding masses. We did not detect any H i emission from our fifth target, R Aqr (a symbiotic binary), but measured a 1.4 GHz continuum flux density of 18:8 AE 0:7 mJy. R Aqr is a previously known radio source, and the 1.4 GHz emission likely arises primarily from free-free emission from an ionized circumbinary envelope.

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“…Carbon is, however, depleted by a factor of "'7 and silicon by "'4 with respect to cosmic abundances. Similar situation prevails in other symbiotic stars-e.g., R Aqr (Michalitsianos, Kafatos, and Hobbs 1980) and RW Hya (Kafatos, Michalitsianos, and Hobbs 1980).…”

Section: B) Nebular Parametersmentioning

confidence: 99%

IUE observations of the peculiar star RX Puppis

Kafatos

Michalitsianos

Feibelman

1982

ApJ

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We have obtained the first high-dispersion observations of RX Pup in the wavelength region 1200-2000 A with the International Ultraviolet Explorer. RX Pup has been classified a symbiotic star and has been compared to slow novae as well as to 11 Carinae. The anomalies that we observed in high-excitation lines in RX Pup such as He II, 0 III], C III], C IV, and Si IIIl that show split line profiles, Doppler displaced multiple components, and possible inverse P Cygni profiles inN III] and N IV J suggest dynamic activity in circumstellar material that probably has the form of rings and/or gas streamers between the cool giant and the hot companion. The continuum observed by us in low dispersion is fairly flat in the wavelength region 1200-2000 A and rises toward longer wavelengths in the region 2000-3200 A. It cannot be due to a star earlier than AO II. Alternatively it may be from an accretion disk. We find electron densities in the line-emitting region in the range 10 9-10 11 em-3 , temperatures in the range 10,000-20,000 K, and linear sizes :S a few x 10 13 em. We find that the photoionizing radiation may be due to the presence of an unseen, hot subdwarf with most probable effective temperature in the range 75,000-90,000 K. Alternatively it may be due to an accretion disk around a secondary with boundary layer temperature-10 5 K. Short-range as well as long-range monitoring of this very interesting object in the far-UV would be very helpful in understanding the nature of its peculiar properties and the connection between slow novae and symbiotic stars.

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IUE observations of circumstellar emission from the late type variable R Aquarii /M7 + pec/

Cited by 28 publications

References 3 publications

The symbiotic binary system RX Puppis: a possible recurrent nova with a Mira companion

The symbiotic binary system RX Puppis: a possible recurrent nova with a Mira companion

Very Large Array Observations of Hiin the Circumstellar Envelopes of Asymptotic Giant Branch Stars

IUE observations of the peculiar star RX Puppis

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