Sampling molecular gas in the Helix planetary nebula: Variation in HNC/HCN with UV flux

We report on observations of the J = 2-1 line of CO to study the distribution and kinematics of the molecular gas in the bipolar planetary nebula NGC 2346. The data were obtained with the National Radio Astronomy Observatory 12-m telescope whose beamsize (FWHM = 30″) partially resolves the CO emitting region. A map of the velocity integrated emission shows a roughly rectangular distribution, approximately 53″ × 34″, oriented along the minor axis of the optical nebula. The CO spectrum towards the central star system is strongly double peaked. The mapping data show that this results from two distinct regions which are offset south-east and north-west of the center with radial velocities which are, respectively, larger and smaller than that of the star system. Overall the CO data are consistent with an expanding and partially disrupted distribution of molecular gas around the waist of the optical nebula. Mass estimates confirm that a substantial amount of the matter ejected by the star system is still in molecular form.

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PHL 932: When Is a Planetary Nebula Not a Planetary Nebula?

Publications of the Astronomical Society of Australia ◽

10.1071/as09043 ◽

2010 ◽

Vol 27 (2) ◽

pp. 203-209 ◽

Cited By ~ 31

Author(s):

David J. Frew ◽

Greg J. Madsen ◽

Simon J. O'Toole ◽

Quentin A. Parker

Keyword(s):

Interstellar Medium ◽

High Latitude ◽

Planetary Nebula ◽

Large Body ◽

Molecular Gas ◽

Evolutionary Status ◽

Compelling Evidence ◽

Extensive Region ◽

Multi Wavelength ◽

Emission Nebula

AbstractThe emission nebula around the subdwarf B (sdB) star PHL 932 is currently classified as a planetary nebula (PN) in the literature. Based on a large body of multi-wavelength data, both new and previously published, we show here that this low-excitation nebula is in fact a small Strömgren sphere (Hii region) in the interstellar medium around this star. We summarise the properties of the nebula and its ionizing star, and discuss its evolutionary status. We find no compelling evidence for close binarity, arguing that PHL 932 is an ordinary sdB star. We also find that the emission nebulae around the hot DO stars PG 0108 + 101 and PG 0109 + 111 are also Strömgren spheres in the ISM, and along with PHL 932, are probably associated with the same extensive region of high-latitude molecular gas in Pisces–Pegasus.

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Comprehensive Panchromatic Data Analyses and Photoionization Modeling of NGC 6781

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318006440 ◽

2018 ◽

Vol 14 (S343) ◽

pp. 514-515

Author(s):

Toshiya Ueta ◽

Masaaki Otsuka ◽

Keyword(s):

Planetary Nebula ◽

Milky Way ◽

Spectral Energy Distribution ◽

Central Star ◽

Spectral Energy ◽

Molecular Gas ◽

Material Recycling ◽

Data Analyses ◽

Dust Component ◽

Data Points

AbstractWe characterized the dusty circumstellar nebula and central star of the C-rich bipolar planetary nebula (PN) NGC 6781 using our own Herschel data augmented with the archival data from UV to radio and constructed one of the most comprehensive photoionization PN models ever produced consisting of the ionized, atomic and molecular gas components as well as the dust component. We reproduced the observed spectral energy distribution (SED), constrained by 136 observational data points. The total nebula mass was estimated to be 0.41 M⊙, with a significant fraction (about 70 %) of it existing in the photo-dissociation region (PDR) surrounding the ionized nebula. This finding demonstrates the critical importance of the PDR in PNe, which are typically recognized as the hallmark of ionized/H+ region. It is therefore essential to characterize the PDR of the circumstellar nebula to understand material recycling in the Milky Way and other galaxies.

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Detection of HCN Directl‐Type Transitions Probing Hot Molecular Gas in the Proto–Planetary Nebula CRL 618

The Astrophysical Journal ◽

10.1086/367629 ◽

2003 ◽

Vol 586 (1) ◽

pp. 338-343 ◽

Cited By ~ 24

Author(s):

S. Thorwirth ◽

F. Wyrowski ◽

P. Schilke ◽

K. M. Menten ◽

S. Brunken ◽

...

Keyword(s):

Planetary Nebula ◽

Molecular Gas

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The dust and molecular gas cloud surrounding a planetary nebula - NGC 7027

The Astrophysical Journal ◽

10.1086/163850 ◽

1986 ◽

Vol 300 ◽

pp. 749 ◽

Cited By ~ 5

Author(s):

H. A., Jr. Thronson ◽

J. Bally

Keyword(s):

Planetary Nebula ◽

Molecular Gas ◽

Ngc 7027 ◽

Gas Cloud

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Red Giant Mass Loss and Planetary Nebula Formation

International Astronomical Union Colloquium ◽

10.1017/s0252921100062965 ◽

1989 ◽

Vol 106 ◽

pp. 226-226

Author(s):

P.J. Huggins ◽

A.P. Healy

Keyword(s):

Mass Loss ◽

Planetary Nebula ◽

Planetary Nebulae ◽

Central Star ◽

Molecular Gas ◽

Red Giants ◽

Extensive Search ◽

Red Giant

It is generally believed that red giant mass loss plays some role in the formation of planetary nebulae (PNe), but the connection is not clearly understood. To investigate this issue we have undertaken an extensive search for molecular gas in PNe, which is likely to be remnant material of the red giant wind not yet ionized by the central star. The search has been carried out with the NRAO 12 m telescope in the 1.3 mm line of 00 which is widely observable in the molecular winds of red giants.

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Central kiloparsec of NGC 1326 observed with SINFONI

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936451 ◽

2020 ◽

Vol 638 ◽

pp. A53

Author(s):

Nastaran Fazeli ◽

Gerold Busch ◽

Andreas Eckart ◽

Françoise Combes ◽

Persis Misquitta ◽

...

Keyword(s):

Black Hole ◽

Galaxy Evolution ◽

Near Infrared ◽

Velocity Fields ◽

Molecular Gas ◽

Nearby Galaxy ◽

Stellar Content ◽

Stellar Rotation ◽

Supermassive Black Hole ◽

Integral Field Spectrograph

Gas inflow processes in the vicinity of galactic nuclei play a crucial role in galaxy evolution and supermassive black hole growth. Exploring the central kiloparsec of galaxies is essential to shed more light on this subject. We present near-infrared H- and K-band results of the nuclear region of the nearby galaxy NGC 1326, observed with the integral-field spectrograph SINFONI mounted on the Very Large Telescope. The field of view covers 9″ × 9″ (650 × 650 pc2). Our work is concentrated on excitation conditions, morphology, and stellar content. The nucleus of NGC 1326 was classified as a LINER, however in our data we observed an absence of ionised gas emission in the central r ∼ 3″. We studied the morphology by analysing the distribution of ionised and molecular gas, and thereby detected an elliptically shaped, circum-nuclear star-forming ring at a mean radius of 300 pc. We estimate the starburst regions in the ring to be young with dominating ages of < 10 Myr. The molecular gas distribution also reveals an elongated east to west central structure about 3″ in radius, where gas is excited by slow or mild shock mechanisms. We calculate the ionised gas mass of 8 × 105 M⊙ completely concentrated in the nuclear ring and the warm molecular gas mass of 187 M⊙, from which half is concentrated in the ring and the other half in the elongated central structure. The stellar velocity fields show pure rotation in the plane of the galaxy. The gas velocity fields show similar rotation in the ring, but in the central elongated H2 structure they show much higher amplitudes and indications of further deviation from the stellar rotation in the central 1″ aperture. We suggest that the central 6″ elongated H2 structure might be a fast-rotating central disc. The CO(3–2) emission observations with the Atacama Large Millimeter/submillimeter Array reveal a central 1″ torus. In the central 1″ of the H2 velocity field and residual maps, we find indications for a further decoupled structure closer to a nuclear disc, which could be identified with the torus surrounding the supermassive black hole.

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