IC 4406: A Radio‐Infrared View

Cerrigone, L.; Hora, J. L.; Umana, G.; Trigilio, C.

doi:10.1086/589228

Cited by 4 publications

(3 citation statements)

References 23 publications

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“…Nevertheless, in the near-IR, where the central star and dust fluxes are at a minimum, the free-free contribution to the observed flux may not be much smaller than the contributions from the other emitting components. For example, in the evolved PN IC 4406 a near-IR excess, previously supposed to indicate a hot-dust component, has been explained as a free-free contribution (Cerrigone et al 2008b). Therefore, we decided to estimate the Gaunt factor following Karzas & Latter (1961) for a 10 4 K electron temperature, extending the calculation of the emission curve from the cm range to 0.8 µm.…”

Section: Modeling the Spectral Energy Distributionmentioning

confidence: 99%

“…Y is the value given as input in DUSTY and τ 100 is given by the code as an output. For δ, whose value depends on the evolutionary stage, we consider a typical value of 200. k 100 depends on the chemistry of the envelope: we use 92 g cm −2 for amorphous carbon (Cerrigone et al 2008b) and 34 g cm −2 for silicates (Sarkar & Sahai 2006). We have used the values for silicates not only in the targets that we have classified as O-rich, but also in mixed-chemistry environments, neglecting any contribution from C-bearing molecules.…”

Section: Circumstellar Mass Calculationmentioning

confidence: 99%

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SPITZERDETECTION OF POLYCYCLIC AROMATIC HYDROCARBONS AND SILICATE FEATURES IN POST-AGB STARS AND YOUNG PLANETARY NEBULAE

Cerrigone¹,

Hora²,

Umana³

et al. 2009

ApJ

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We have observed a small sample of hot post-AGB stars with the InfraRed Array Camera (IRAC) and the InfraRed Spectrograph (IRS) on-board the Spitzer Space Telescope. The stars were selected from the literature on the basis of their far-Infrared excess (i.e., post-AGB candidates) and B spectral type (i.e., close to the ionization of the envelope). The combination of our IRAC observations with 2MASS and IRAS catalog data, along with previous radio observations in the cm range (where available) allowed us to model the SEDs of our targets and find that in almost all of them at least two shells of dust at different temperatures must be present, the hot dust component ranging up to 10 3 K. In several targets grains larger than 1 µm are needed to match the far-IR data points. In particular, in IRAS 17423-1755 grains up to 100 µm must be introduced to match the emission in the mm range.We obtained IRS spectra to identify the chemistry of the envelopes and found that more than 1 / 3 of the sources in our sample have mixed chemistry, showing both mid-IR bands attributed to Polycyclic Aromatic Hydrocarbons (PAH) and silicate features. The analysis of the PAH features indicates that these molecules are located in the outflows, far away from the central stars. We consider the larger than expected percentage of mixed-chemistry targets as a selection bias towards stars with a disk or torus around them. Our results strengthen the current picture of mixed chemistry being due to the spatial segregation of different dust populations in the envelopes.

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Section: Modeling the Spectral Energy Distributionmentioning

confidence: 99%

Section: Circumstellar Mass Calculationmentioning

confidence: 99%

SPITZERDETECTION OF POLYCYCLIC AROMATIC HYDROCARBONS AND SILICATE FEATURES IN POST-AGB STARS AND YOUNG PLANETARY NEBULAE

Cerrigone¹,

Hora²,

Umana³

et al. 2009

ApJ

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“…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. Cerrigone et al (2008) analyzed IRAC images, in conjunction with 4.8 and 8.6 GHz radio continuum observations, of the bipolar PN IC 4406, and concluded that there exist at least three dust components at temperatures ranging from 57 to 700 K.…”

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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A revised distance scale of planetary nebulae

Ortiz¹

2013

A&A

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Context. The advent of large-scale, high-sensitivity surveys of the Galaxy (2MASS, WISE, Spitzer, etc.) has allowed detection of a large number of planetary nebulae (PNe), some of them at large distances. Aims. I propose a new distance scale of planetary nebulae, based on two main quantities: the flux density (or magnitude) at 8 μm and the nebular apparent size. Methods. I used these quantities to calculate the specific intensity of the radiation I 8 μm , which decreases as the nebula evolves. The PNe situated in the Large Magellanic Cloud (LMC) with 8 μm photometry obtained by Spitzer and diameter obtained from HST observations were used as calibrators. Results. After calibration, I recalculated distances of PNe in the LMC, and they show a one-sigma spread of 10 kpc (20%). Eventually, I applied the method to a sample of 47 Galactic PNe observed during the Spitzer survey. These results showed agreement within 0.2 dex with the distances determined with another method of calibrating with PNe in the LMC. Conclusions. The main advantage of the present distance scale is that it is nearly "extinction free", which makes it especially suited to PNe severely affected by interstellar extinction, such as the Galactic disc and bulge. On the other hand, the method requires an unbiased determination of the nebular size, which might be quite uncertain for PNe with extended faint features, such as haloes and ansae.

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IC 4406: A Radio‐Infrared View

Cited by 4 publications

References 23 publications

SPITZERDETECTION OF POLYCYCLIC AROMATIC HYDROCARBONS AND SILICATE FEATURES IN POST-AGB STARS AND YOUNG PLANETARY NEBULAE

SPITZERDETECTION OF POLYCYCLIC AROMATIC HYDROCARBONS AND SILICATE FEATURES IN POST-AGB STARS AND YOUNG PLANETARY NEBULAE

Spitzer observations of planetary nebulae

A revised distance scale of planetary nebulae

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