Mid-infrared imaging of 18 planetary nebulae using the <i>Spitzer Space Telescope</i>

Phillips, J. P.; Ramos-Larios, G.

doi:10.1111/j.1365-2966.2007.12580.x

Cited by 36 publications

(81 citation statements)

References 62 publications

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“…We regard it as more likely that such variations are a consequence of increasing optical depths, however, and the fact that we are looking through increasing depths of PDRs located outside of the ionized regime – PDRs which wrap around the sources, and would therefore have proportionately greater effect at the ionized limits of the flows. We note that fluxes in the 8 μm band tend to be much larger than in the 5.8 μm band, and those in the 5.8 μm are larger than in the 3.6 and 4.5 μm bands. This is universally the case for all of the sources considered here, and is also found to be the case in compact H ii regions (Phillips & Ramos‐Larios 2008c) and in the majority of planetary nebulae (Phillips & Ramos‐Larios 2008a,b). The ISO spectra for compact H ii regions (Peeters et al 2002) suggests that this is likely to arise because the 7.7 + 8.6 μm PAH bands are much stronger than that at 6.2 μm, whilst the 6.2 μm band is stronger than that at 3.3 μm.…”

Section: Discussionsupporting

confidence: 73%

“…All of these bipolars are therefore likely to be associated with YSOs. This represents an important and useful way of identifying such sources, since the self‐same survey also contains several examples of bipolar planetary nebulae, certain of which have been analysed by Phillips & Ramos‐Larios (2008a,b). The IRAS colour plane allows us to distinguish between these sources.…”

Section: Observationsmentioning

confidence: 99%

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The mid- and near-infrared structures of seven young stellar bipolar outflows

Phillips¹,

Perez-Grana²

2009

Monthly Notices of the Royal Astronomical Society

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Bipolar outflows appear to represent the ubiquitous products of post‐ and pre‐main‐sequence stellar evolution. However, although the outflows around young stellar objects (YSOs) have been observed over a broad range of wavelengths, from the ultraviolet through to the radio, there has been very little mapping of these sources at mid‐infrared (MIR) wavelengths. The recent advent of the Spitzer Space Telescope (SST) now permits us to correct this deficiency, and we present maps, profiles and images of seven bipolar sources, six of which appear to be new to the literature. It is found that although the bipolars have differing morphologies, reflecting the differing phases of their evolution, they nevertheless have many properties in common. These include the evidence for central tori of neutral material, in some cases associated with appreciable levels of extinction. We also note evidence for exterior photodissociation regimes (PDRs) about the ionized flows, responsible for strong polycyclic aromatic hydrocarbon (PAH) band emission in the 5.8 and 8 μm bands. Such PDRs are also likely to be responsible for appreciable variations in flux ratios with position within the sources. Finally, it is noted that a large fraction of the sources are associated with stars in the earliest phases of their evolution – Class 0 and I stars in which infalling material is important, and dominates their spectral energy distributions in the MIR. One of the sources (G035.2−00.7) has previously been observed at visual, near‐infrared (NIR) and millimetric wavelengths, whence it has been proposed that the spatio‐kinematic properties of the source are best explained in terms of multiple nuclear outflows, and/or precession of an ionized jet. Our present results suggest that the characteristics of this source are much simpler than has previously been inferred, and suggest that the outflow can be described in terms of a very low‐collimation bipolar outflow. Finally, we have also compared the present MIR results with NIR mapping from the Two Micron All Sky Survey (2MASS). These show that whilst the structures of the sources are comparable within these differing wavelength regimes, there are differences attributable to grain extinction and shock or fluorescently excited H2.

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Section: Discussionsupporting

confidence: 73%

Section: Observationsmentioning

confidence: 99%

The mid- and near-infrared structures of seven young stellar bipolar outflows

Phillips¹,

Perez-Grana²

2009

Monthly Notices of the Royal Astronomical Society

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“…The flux densities of radio continuum in the different sources were measured by the following authors: IRAS 17103−3702 (Rodríguez et al 1985;Payne et al 1988), 17347−3139 (Gómez et al 2005;Tafoya et al 2009), JaSt23 (Van de Steene & Jacoby 2001), IRAS 17393-2727(Pottasch et al 1987, this paper), IRAS 19219−0947 (Seaquist & Davis 1983Christianto & Seaquist 1998;Condon & Kaplan 1998), and IRAS 19255+2123 (Aaquist & Kwok 1991Miranda et al 2001;Gómez et al 2009). The Spitzer fluxes for IRAS 17103−3702 (triangles) and J, H, K fluxes (squares) for IRAS 17393-2727 were measured by Phillips & Ramos-Larios (2008) and Ramos-Larios et al (2012), respectively. below the sensitivity of the instrument. However, the general trend is that the OH spectra are relatively symmetrical in those stars.…”

Section: Spectral Properties Of Oh Masersmentioning

confidence: 99%

An updated catalog of OH-maser-emitting planetary nebulae

Uscanga

Gómez

Suárez

et al. 2012

A&A

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Aims. We studied the characteristics of planetary nebulae (PNe) that show both OH maser and radio continuum emission (hereafter OHPNe). These have been proposed to be very young PNe, and therefore, they could be key objects for understanding the formation and evolution of PNe. Methods. We consulted the literature searching for interferometric observations of radio continuum and OH masers toward evolved stars, including the information from several surveys. We also processed radio continuum and OH maser observations toward PNe in the Very Large Array data archive. The high positional accuracy provided by interferometric observations allow us to confirm or reject the association between OH maser and radio continuum emission. Results. We found a total of six PNe that present both OH maser and radio continuum emissions, as confirmed with radio interferometric observations. These are bona fide OHPNe. The confirmed OHPNe present a bipolar morphology in resolved images of their ionized emission at different wavelengths, suggesting that the OH maser emission in PNe is related to nonspherical mass-loss phenomena. The OH maser spectra in PNe present a clear asymmetry, tending to show blueshifted emission with respect to the systemic velocity. Their infrared colors suggest that most of these objects are very young PNe. OHPNe do not form a homogeneous group, and seem to represent a variety of different evolutionary stages. We suggest that OH masers pumped in the asymptotic giant branch (AGB) phase may disappear during the post-AGB phase, but reappear once the source becomes a PN and its radio continuum emission is amplified by the OH molecules. Therefore, OH maser emission could last significantly longer than the previously assumed 1000 yr after the end of the AGB phase. This maser lifetime may be longer in PNe with more massive central stars, which ionize a larger amount of gas in the envelope.

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“…A detailed analysis of IRAC images of the Helix Nebula complemented by spectroscopic observations was carried out by Hora et al (2006). Phillips & Ramos-Larios (2008a) analyzed quantitatively IRAC images of 18 PNe and suggest that PAH emission from PDRs contributes significantly to the observed mid-IR fluxes. Phillips & Ramos-Larios (2010) extended their analysis to seven bipolar PNe, assessing the roles of PAH emission from PDRs and shock excited H 2 emission, and discussing the color variations from the cores to the lobes.…”

Section: Irac Observations Of Pnementioning

confidence: 99%

Spitzer observations of planetary nebulae

Chu¹

2011

Proc. IAU

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Abstract. The Spitzer Space Telescope has three science instruments (IRAC, MIPS, and IRS) that can take images at 3. 6, 4.5, 5.8, 8.0, 24, 70, and 160 µm, spectra over 5-38 µm, and spectral energy distribution over 52-100 µm. The Spitzer archive contains targeted imaging observations for more than 100 PNe. Spitzer legacy surveys, particularly the GLIMPSE survey of the Galactic plane, contain additional serendipitous imaging observations of PNe. Spitzer imaging and spectroscopic observations of PNe allow us to investigate atomic/molecular line emission and dust continuum from the nebulae as well as circumstellar dust disks around the central stars. Highlights of Spitzer observations of PNe are reviewed in this paper.

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Mid-infrared imaging of 18 planetary nebulae using the Spitzer Space Telescope

Cited by 36 publications

References 62 publications

The mid- and near-infrared structures of seven young stellar bipolar outflows

The mid- and near-infrared structures of seven young stellar bipolar outflows

An updated catalog of OH-maser-emitting planetary nebulae

Spitzer observations of planetary nebulae

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