H I and CO observations of the circumnebular envelopes of planetary nebulae

Gussie, G. T.; Taylor, A. R.

doi:10.1093/mnras/273.3.801

Cited by 23 publications

(15 citation statements)

References 21 publications

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“…This might be an indication of several components, meaning that this object might have much structure, but a further more detailed investigation is needed. CO (J = 3−2) was observed in this object using the JCMT, but only upper limits were obtained (Gussie & Taylor 1995). CO (J = 1−0) was detected in this object using the 13.7 m millimetre-wave telescope of Purple Mountain Observatory (Zhang et al 2000).…”

Section: Planetary Nebulaementioning

confidence: 81%

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Opening PANDORA’s box: APEX observations of CO in PNe

Guzmán-Ramírez

Gómez-Ruiz

Boffin

et al. 2018

A&A

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Context. Observations of molecular gas have played a key role in developing the current understanding of the late stages of stellar evolution. Aims. The survey Planetary nebulae AND their cO Reservoir with APEX (PANDORA) was designed to study the circumstellar shells of evolved stars with the aim to estimate their physical parameters. Methods. Millimetre carbon monoxide (CO) emission is the most useful probe of the warm molecular component ejected by low-to intermediate-mass stars. CO is the second-most abundant molecule in the Universe, and the millimetre transitions are easily excited, thus making it particularly useful to study the mass, structure, and kinematics of the molecular gas. We present a large survey of the CO (J = 3−2) line using the Atacama Pathfinder EXperiment (APEX) telescope in a sample of 93 proto-planetary nebulae and planetary nebulae. Results. CO (J = 3−2) was detected in 21 of the 93 objects. Only two objects (IRC+10216 and PN M2-9) had previous CO (J = 3−2) detections, therefore we present the first detection of CO (J = 3−2) in the following 19 objects: Frosty Conclusions. CO (J = 3−2) was detected in all 4 observed pPNe (100%), 15 of the 75 PNe (20%), one of the 4 wide binaries (25%), and in 1 of the 10 close binaries (10%). Using the CO (J = 3−2) line, we estimated the column density and mass of each source. The H 2 column density ranges from 1.7 × 10 18 to 4.2 × 10 21 cm −2 and the molecular mass ranges from 2.7 × 10 −4 to 1.7 × 10 −1 M .

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Section: Planetary Nebulaementioning

confidence: 81%

“…Its line width is smaller than 5 km s −1 , which might be an indication that the emission comes from the ISM rather than the nebula. CO (J = 3−2) was observed in this object using the JCMT, but only upper limits were obtained (Gussie & Taylor 1995).…”

Section: Planetary Nebulaementioning

confidence: 82%

Opening PANDORA’s box: APEX observations of CO in PNe

Guzmán-Ramírez

Gómez-Ruiz

Boffin

et al. 2018

A&A

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“…Therefore, important information related with the mass loss process can be gathered from investigations of the scattering processes of the UV radiation originating from the center region. Taylor, Gussie & Pottasch (1990) performed H I 21 cm radio observations for a number of compact planetary nebulae (see also Altschuler et al 1986, Gussie & Taylor 1995, Schneider et al 1987. Their target selection was made on the basis of high radio brightness temperature, which is indicative of the nebular compactness.…”

Section: Introductionmentioning

confidence: 99%

RAMAN-SCATTERED He II λ6545 IN THE YOUNG AND COMPACT PLANETARY NEBULA NGC 6790

Kang

Lee

2009

ApJ

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We present the high resolution spectra of the young and compact planetary nebula NGC 6790 obtained with the echelle spectrograph at Bohyunsan Optical Astronomy Observatory and report the discovery of Raman scattered He II λ 6545 in this object. This line feature is formed in a thick neutral region surrounding the hot central star, where He IIλ 1025 line photons are scattered inelastically by hydrogen atoms. A Monte Carlo technique is adopted to compute the line profiles with a simple geometric model, in which the neutral region is in the form of a cylindrical shell that is expanding from the central star. From our line profile analysis, the expansion velocity of the H I region lies in the range v exp = 15 − 19 km s −1 . Less stringent constraints are put on the H I column density N HI and covering factor C, where the total flux of Raman He IIλ6545 is consistent with their product CN HI ∼ 0.5 ×10 20 cm −2 . The Monte Carlo profiles from stationary emission models exhibit deficit in the wing parts. A much better fit is obtained when the He II emission region is assumed to take the form of a ring that slowly rotates with a rotation speed ∼ 18 km s −1 . Brief discussions are presented regarding the mass loss processes and future observations. Subject headings: planetary nebulae -planetary nebulae: individual NGC 6790radiative transfer -scattering -mass loss

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“…While the relative importance of these various effects remains largely unknown, models predict that some fraction of the hydrogen in AGB circumstellar envelopes should be atomic and, consequently, should be observable via the H i 21 cm line (Clegg et al 1983;Glassgold & Huggins 1983;Villaver et al 2002). Furthermore, H i has been detected in emission and/or absorption toward several planetary nebulae ( Rodríguez & Moran 1982;Altschuler et al 1986;Schneider et al 1987;Taylor & Pottasch 1987;Taylor et al 1989Taylor et al , 1990Gussie & Taylor 1995;Rodríguez et al 2000Rodríguez et al , 2002; the detected material was presumably expelled by the stars during their AGB stage, although the details of this process are still poorly understood (e.g., Rodríguez et al 2002).…”

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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H I and CO observations of the circumnebular envelopes of planetary nebulae

Cited by 23 publications

References 21 publications

Opening PANDORA’s box: APEX observations of CO in PNe

Opening PANDORA’s box: APEX observations of CO in PNe

RAMAN-SCATTERED He II λ6545 IN THE YOUNG AND COMPACT PLANETARY NEBULA NGC 6790

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

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