scholarly journals ALMA imaging of the nascent planetary nebula IRAS 15103–5754

2018 ◽  
Vol 480 (4) ◽  
pp. 4991-5009 ◽  
Author(s):  
José F Gómez ◽  
Gilles Niccolini ◽  
Olga Suárez ◽  
Luis F Miranda ◽  
J Ricardo Rizzo ◽  
...  
Keyword(s):  
Mass Loss ◽  
High Velocity ◽  
Planetary Nebula ◽  
Symmetry Axis ◽  
Stellar System ◽  
Line Emission ◽  
Ionized Gas ◽  
Molecular Line ◽  
Common Envelope ◽  
Loss Event

ABSTRACT We present continuum and molecular-line (CO, C18O, HCO+) observations carried out with the Atacama Large Millimeter/submillimeter Array toward the ‘water fountain’ star IRAS 15103–5754, an object that could be the youngest planetary nebula (PN) known. We detect two continuum sources, separated by 0.39 ± 0.03 arcsec. The emission from the brighter source seems to arise mainly from ionized gas, thus confirming the PN nature of the object. The molecular-line emission is dominated by a circumstellar torus with a diameter of ≃0.6 arcsec (2000 au) and expanding at ≃23 km s−1. We see at least two gas outflows. The highest-velocity outflow (deprojected velocities up to 250 km s−1), traced by the CO lines, shows a biconical morphology, whose axis is misaligned ≃14° with respect to the symmetry axis of the torus, and with a different central velocity (by ≃8 km s−1). An additional high-density outflow (traced by HCO+) is oriented nearly perpendicular to the torus. We speculate that IRAS 15103–5754 was a triple stellar system that went through a common envelope phase, and one of the components was ejected in this process. A subsequent low-collimation wind from the remaining binary stripped out gas from the torus, creating the conical outflow. The high velocity of the outflow suggests that the momentum transfer from the wind is extremely efficient, or that we are witnessing a very energetic mass-loss event.

M 1–92 revisited: the chemistry of a common envelope nebula?

2018 ◽  
Vol 14 (S343) ◽  
pp. 343-344
Author(s):  
Javier Alcolea ◽  
Marcelino Agúndez ◽  
Valentín Bujarrabal ◽  
Arancha Castro Carrizo ◽  
Jean-François Desmurs ◽  
...  
Keyword(s):  
Mass Loss ◽  
Planetary Nebula ◽  
Central Star ◽  
Molecular Line ◽  
Common Envelope ◽  
Loss Event

AbstractWe report on new molecular-line observations of the bipolar pre-planetary nebula M 1–92. The new IRAM 30 m MRT and NOEMA data shows the presence of shock induced chemistry in the nebula. From the derived [17O]/[18O] ratio, we suggest that the sudden mass loss event responsible for the formation of the nebula 1200 yr ago may also have resulted in the premature end of the AGB phase of the central star.

scholarly journals Circumstellar spirals/shells/arcs: the message from binary stars

2016 ◽  
Vol 12 (S323) ◽  
pp. 199-206
Author(s):  
Hyosun Kim
Keyword(s):  
Mass Loss ◽  
Binary Stars ◽  
Planetary Nebula ◽  
Fossil Record ◽  
Asymptotic Giant Branch ◽  
Agb Stars ◽  
Circumstellar Envelopes ◽  
Molecular Line ◽  
The Past ◽  
Recurrent Patterns

AbstractA consensus has grown in the past few decades that binarity is key to understanding the morphological diversities of the circumstellar envelopes (CSEs) surrounding stars in the Asymptotic Giant Branch (AGB) to Planetary Nebula (PN) phase. The possible roles of binaries in their shaping have, however, yet to be confirmed. Meanwhile, recurrent patterns are often found in the CSEs of AGB stars and the outer halos of PNe, providing a fossil record of the mass loss during the AGB phase. In this regard, recent molecular line observations using interferometric facilities have revealed the spatio-kinematics of such patterns. Numerical simulations of binary interactions producing spiral-shells have been extensively developed, revealing new probes for extracting the stellar and orbital properties from these patterns. I review recent theoretical and observational investigations on the circumstellar spiral-shell patterns and discuss their implications in linking binary properties to the asymmetric ejection events in the post-AGB phase.

scholarly journals Probing chemical processes in AGB stars

2008 ◽  
Vol 4 (S251) ◽  
pp. 201-206 ◽  
Author(s):  
Fredrik L. Schöier ◽  
Hans Olofsson
Keyword(s):  
Radiative Transfer ◽  
Mass Loss ◽  
Line Emission ◽  
Chemical Processes ◽  
Agb Stars ◽  
Molecular Line ◽  
Large Sample ◽  
Preliminary Results ◽  
Transfer Modelling ◽  
Non Equilibrium

AbstractWe are conducting multi-transition observations of circumstellar line emission from common molecules such as HCN, SiO, CS, SiS and CN for a large sample of AGB stars with varying photospheric C/O-ratios and mass-loss charachteristics. Our recently published results for SiO and SiS clearly show that major constraints on the relative roles of non-equilibrium chemistry, dust condensation, and photodissociation can be obtained from the study of circumstellar molecular line emission. Presented here are also preliminary results based on detailed radiative transfer modelling of HCN line emission.

scholarly journals The LMC Planetary Nebula N66 Revisited: Nebular Kinematics and Stellar Models

2003 ◽  
Vol 209 ◽  
pp. 579-580
Author(s):  
M. Peña ◽  
W.-R. Hamann ◽  
M. T. Ruiz
Keyword(s):  
Mass Loss ◽  
Planetary Nebula ◽  
Central Star ◽  
Main Body ◽  
Complex Morphology ◽  
Loss Event ◽  
Stellar Models ◽  
Dark Material

LMC-N66 is an extraordinary planetary nebula whose central star underwent a violent mass loss event which has lasted for 10 years. The outburst reached its maximum in 1994. Since then the star has been slowly fading. During the stellar outburst, the nebular lines have shown no changes.The nebula shows a complex morphology. Two very bright lobes at both sides of the central star, almost aligned in the E-W direction, constitute the main body of the nebula. Several knots and filaments are conspicuous over the surface lying preferentially on the S-E and N-W directions. A couple of faint, extended loops are also detected in the S-E and N-W directions at both sides of the star. The extension of these loops are larger than 0.5 pc at the LMC distance. A no emitting-zone in the S-W quadrant, seems to be part of a dusty toroid around the central star, although the central star is not obscured by such a dark material (see Blades et ale 1992 for a description of N66 morphology).

scholarly journals High Velocity Ionized Gas near IRS 16

1989 ◽  
Vol 136 ◽  
pp. 525-526
Author(s):  
T. R. Geballe ◽  
J. B. Lugten
Keyword(s):  
High Velocity ◽  
Spectral Properties ◽  
Radial Flow ◽  
Line Emission ◽  
Compact Object ◽  
Characteristic Dimension ◽  
Ionized Gas ◽  
Spatially Resolved ◽  
The Galaxy ◽  
Important Means

An important means of studying the unusual activity within the central ~0.15 parsec of the galaxy is to obtain detailed information on the high velocity ionized gas there. This gas was first reported by Hall, Kleinmann, and Scoville (1982), who observed the He I line at 2.06 μm. Subsequent observations of this line and the Br ∝ and Br γ lines of H I (4.05 μm and 2.17 μm, respectively) by Geballe et al. (1984, 1987) have defined the coarse spatial and spectral properties more accurately. Briefly, the broad (i.e., |v| > 400 km/s) line emission, as observed at velocity resolutions as high as 400 km/s and angular resolutions as high as 2.5″ (1) extends approximately to +/– 700 km/s (e.g., see Fig. 1), (2) is spatially resolved, with a characteristic dimension of 3″, (3) is centered approximately on IRS 16C, and (4) appears to be due neither to rotational motion nor to a simple radial flow from or onto a single compact object. These properties are difficult to understand in terms of simple models, and point out the necessity for further measurements at higher spectral and spatial resolutions.

scholarly journals Circumstellar molecular line emission from S-type AGB stars: mass-loss rates and SiO abundances

2009 ◽  
Vol 499 (2) ◽  
pp. 515-527 ◽  
Author(s):  
S. Ramstedt ◽  
F. L. Schöier ◽  
H. Olofsson
Keyword(s):  
Mass Loss ◽  
Line Emission ◽  
Agb Stars ◽  
Molecular Line ◽  
Loss Rates

scholarly journals The Nature of the High Velocity Flow in CRL 618

1993 ◽  
Vol 155 ◽  
pp. 347-347
Author(s):  
R. Neri ◽  
M. Guélin ◽  
S. Guilloteau ◽  
R. Lucas ◽  
S. Garcia-Burillo ◽  
...  
Keyword(s):  
High Velocity ◽  
Planetary Nebula ◽  
Line Emission ◽  
Molecular Flow ◽  
Stellar Winds ◽  
Circumstellar Envelope ◽  
Hii Region ◽  
Molecular Outflow ◽  
Neutral Gas ◽  
Velocity Flow

Using the IRAM interferometer, we have mapped with a 2″.4 = 3″.4 resolution the J = 1 → 0 HCN line emission in the proto–planetary nebula CRL 618. Our maps resolve the 200 kms−1 molecular outflow (Cernicharo et al. 1989), as well as the slowly expanding circumstellar envelope (Bujarrabal et al. 1988), allowing a very precise positioning (≤ 0″.1) of these components with respect to the central HII region. 70% of the HCN envelope emission comes from a very compact, spherically symmetric core of size ≃ 3″.2. The core surrounds the high velocity gas which appears localized in a number of small ‘clumps’ (≤ 0″.5) – see figure. The large range of velocities observed in the ‘clumps’ suggests that we are not observing a decelerating molecular flow, but the impacts of a bipolar outflow on the slowly moving core, close to the HII region. The collision of a neutral gas outflow with high density regions (the ‘clumps’) results in the generation of dissociative shock-waves pushing and tearing the inner surface of the envelope. CRL 618 appears to have reached the stage where the stellar winds begin to disrupt and to scrape through the massive envelope, shortly before it evolves towards a Planetary Nebula.

scholarly journals Molecular-Line Observations of the Remnant AGB Envelopes Around Planetary Nebulae

1993 ◽  
Vol 155 ◽  
pp. 229-229
Author(s):  
R. Sahai ◽  
A. Wootten ◽  
R.E.S. Clegg
Keyword(s):  
Spatial Structure ◽  
Mass Loss ◽  
Line Emission ◽  
Planetary Nebulae ◽  
Molecular Line ◽  
Upper Limits ◽  
Density Enhancement ◽  
Molecular Masses ◽  
Molecular Abundances ◽  
Mapping Program

We present recent results from a “search and mapping” program of molecular line emission (mainly CO) from remnant AGB envelopes around planetary nebulae (PNe), using the SEST (La Silla, Chile). New detections in CO J=2−1 include NGC2899 (0.02K), NGC6369 (0.14K) & NGC7009 (0.08K). In many of the detected PNe, notably NGC3132, IC4406, NGC6302, M1-16, and CPD-56°8032, the molecular envelopes contain 2 kinematically distinct outflows. Mapping of the strongest of these shows (1) that the fast (e.g. Vexp≳40–60 km s−1 in NGC3132, IC4406) outflows have bipolar spatial structure, and (2) there exists an equatorial density enhancement in the slower, more massive [· (M⊙yr−1)>5 10−6(NGC3132), >2 10−5(IC4406)] outflows, which presumably collimates the fast outflow (e.g. Sahai et al. 1990, A & A, 234, L1; Sahai et al. 1992, A & A, 251, 560). The fractional CO abundance in the envelope, f(CO), is probably rather low (<10−4), as a result of photodissociation by the stellar and interstellar UV radiation [e.g. f(CO)≲10−5 in IC4406]. HCN, HCO+, and 13CO have also been detected in several PNe, and sensitive upper limits set on CS, C18O, & C17O (in M1-16), and SO (in NGC3132). Some results are tabulated below, and calculations to estimate the molecular masses, mass-loss rates and molecular abundances are in progress.

scholarly journals Core-halo structures in the 12CO emission of CIT 6, AFGL 618 and IRAS 21282+5050

1997 ◽  
Vol 180 ◽  
pp. 359-359
Author(s):  
M. Meixner ◽  
M.T. Campbell ◽  
W. J. Welch ◽  
L. Likkel ◽  
M. Tafalla
Keyword(s):  
Mass Loss ◽  
Spatial Resolution ◽  
Planetary Nebula ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Line Emission ◽  
Carbon Star ◽  
The Core ◽  
Evolved Stars ◽  
Transfer Modelling

We present full synthesis 12CO J= 1–0 line emission images of three carbon rich evolved stars: CIT 6, AFGL 618 and IRAS 21282+5050. Each of these objects represents a different stage of evolution: CIT 6 is a carbon star still on the AGB, AFGL 618 is a transition object, and IRAS 21282+5050 is a young planetary nebula. Common to all three sources, we find what appears to be two mass loss components: a bright “core” located at the center of the source and a fainter “halo” surrounding the core (see Table below for observed characteristics). We speculate that the bright core was created by a more recent and higher mass loss rate wind than the fainter surrounding halo. However, concrete support for this idea awaits radiative transfer modelling of the 12CO that we are currently pursuing. Our full synthesis data are combined from millimeter interferometry using the Berkeley–Illinois–Maryland millimeter array (BIMA) and single dish maps using the NRAO 12m. We find that full-synthesis imaging, which combines the sensitivity of single dish and the spatial resolution of interferometry, is the only means to reveal such core-halo structures.

scholarly journals Molecular Line Emission from the Young Planetary Nebula NGC 7027

2003 ◽  
Vol 209 ◽  
pp. 272-272
Author(s):  
Tatsuhiko I. Hasegawa ◽  
Sun Kwok
Keyword(s):  
Planetary Nebula ◽  
Small Volume ◽  
Line Emission ◽  
Peak Level ◽  
Ionization Front ◽  
Emission Region ◽  
Molecular Line ◽  
Ngc 7027 ◽  
Line Widths ◽  
Co Emission

NGC 7027 has been observed in eleven molecular species (in seventeen transitions) in the 200 and 300 GHz bands with the James Clarke Maxwell Telescope (Hasegawa & Kwok 2001). The results include a first detection of C2H in this source. The observed spectra of HCO+, H13CO+, HCN, CN, C2H, and CO+ show line widths larger than that of bulk CO emission but coincident with the full width at detection limit of weak wings in CO spectra. The sizes of the HCO+, HCN, and CN emitting regions are 13″ in diameter at half-peak level, significantly smaller than that (60″) of the CO emitting region. The emission of all the observed molecules other than CO and 13CO must originate from a very small volume compared with the entire CO envelope of NGC 7027. Since the central 10″ region is an ionized region, the molecular emission region (except CO) must be geometrically thin (ΔR = 1″ – 2″) and must be close to the ionization front.

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