<i>SPITZER</i>DETECTION OF POLYCYCLIC AROMATIC HYDROCARBONS AND SILICATE FEATURES IN POST-AGB STARS AND YOUNG PLANETARY NEBULAE

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

doi:10.1088/0004-637x/703/1/585

Cited by 55 publications

(82 citation statements)

References 55 publications

(64 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous analyses in LTE formalism are likely to be the source of this discrepancy. The obtained C/O ratio for the objects is consistent with O-rich circumstelar dust detected for some objects of our sample reported by Cerrigone et al (2009) based on infrared observations with the Spitzer Space Telescope and previous radio observations. 4.…”

Section: Discussionsupporting

confidence: 91%

“…12, they can be considered to be oxygen-rich. Similar results for LSE 3, TYC 6234-178-1 were reported by Cerrigone et al (2009) based on the detection of silicate features at 10 μm typical of circumstellar O-rich environments. For LSE 63 and LS IV-12 111, the same authors detected a dual-chemistry circumstellar envelope, associated with the 10 μm feature and silicate features due to PAHs.…”

Section: Oxygen and The α-Elementssupporting

confidence: 88%

“…For example, Kwok (2000) quotes the mechanism of the PN formation in the transition from post-AGB to PNe. Cerrigone et al (2009) quotes the dual-dust chemistry phenomenon observed not only in the transition objects but also during the PN stage. Herwig (2005) mentions the ocurring mechanisms on the AGB nucleosynthesis and the mixing processes, such as dredged-up Based on observations made with the 2.2 m telescope at the European Southern Observatory (La Silla, Chile).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Chemical abundances of hot post-AGB stars

Mello

Daflon

Pereira

et al. 2012

A&A

View full text Add to dashboard Cite

Context. Hot post-AGB stars are luminous objects of low-and intermediate mass (0.8-8 M ) in the final stage of evolution, moving between the asymptotic giant branch (AGB) stars and planetary nebulae. The absorption lines observed in their spectra are typical of early-type stars and their abundance pattern may be associated with the occurence of one or more mixing processes during the previous AGB phase. Aims. To better constrain their observed chemical pattern and evolutionary status, we determined chemical abundances for a sample of hot post-AGB stars selected according to spectroscopic criteria. Methods. The observational data are high-resolution spectra obtained with the FEROS spectrograph. The stellar parameters and chemical composition were obtained from fully consistent non-LTE synthesis.Results. The general abundance pattern reveals relevant nitrogen enrichment, slight depletion in carbon and sulfur and mild excess in helium for most of the objects. One notable exception is LSE 148, with Z = 0.001, which is likely to be a metal-poor object at high galactic latitude. The atmospheric parameters and chemical abundances obtained are discussed in the context of evolutionary models. Mixing processes like the second/third dredged-up and "hot bottom-burning" are invoked to explain the obtained results.

show abstract

Section: Discussionsupporting

confidence: 91%

Section: Oxygen and The α-Elementssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Chemical abundances of hot post-AGB stars

Mello

Daflon

Pereira

et al. 2012

A&A

View full text Add to dashboard Cite

show abstract

“…10, bottom). However, they show a peak on the continuum emission above 25 µm, and they lack the [O IV] line at 26 µm seen in faint LINERs (Cerrigone et al 2009). …”

Section: Host Galaxy Contributionmentioning

confidence: 98%

Nuclear obscuration in LINERs

González‐Martín

Masegosa

Márquez

et al. 2015

A&A

View full text Add to dashboard Cite

Context. Most of the optically classified low-ionisation, narrow emission-line regions (LINERs) nuclei host an active galactic nucleus (AGN). However, how they fit into the unified model (UM) of AGN is still an open question.Aims. The aims of this work are to study at mid-infrared (mid-IR) (1) the Compton-thick nature of LINERs (i.e. hydrogen column densities of N H > 1.5 × 10 24 cm −2 ) and (2) the disappearance of the dusty torus in LINERs predicted from theoretical arguments. Methods. We have compiled all the available low spectral-resolution, mid-IR spectra of LINERs from the InfraRed Spectrograph (IRS) onboard Spitzer. The sample contains 40 LINERs. We have complemented the LINER sample with Spitzer/IRS spectra of PG QSOs, Type-1 Seyferts (S1s), Type-2 Seyferts (S2s), and StarBurst (SB) nuclei. We studied the AGN compared to the starburst content in our sample using different indicators: the equivalent width of the polycyclic aromatic hydrocarbon at 6.2 µm, the strength of the silicate feature at 9.7 µm, and the steepness of the mid-IR spectra. We classified the spectra as SB-dominated and AGN-dominated, according to these diagnostics and compared the average mid-IR spectra of the various classes. Moreover, we studied the correlation between the 12 µm luminosity, νL ν (12 µm), and the 2−10 keV energy band X-ray luminosity, L X (2−10 keV). Results. In 25 out of the 40 LINERs (i.e. 62.5%), the mid-IR spectra are not SB-dominated, similar to the comparison S2 sample (67.7%). The average spectra of both SB-dominated LINERs and S2s are very similar to the average spectrum of the SB class. The average spectrum of AGN-dominated LINERs is different from the average spectra of the other optical classes, showing a rather flat spectrum at 6−28 µm. We find that the average spectrum of AGN-dominated LINERs with X-ray luminosities L X (2−10 keV) > 10 41 erg/s is similar to the average mid-IR spectrum of AGN-dominated S2s. However, faint LINERs (i.e. L X (2−10 keV) < 10 41 erg/s) show flat spectra different from any of the other optical classes. The correlation between νL ν (12 µm) and L X (2−10 keV) for AGN nicely extends towards low luminosities only if SB-dominated LINERs are excluded and if the 2−10 keV band X-ray luminosity is corrected in Compton-thick LINER candidates. Conclusions. We find that LINERs proposed as Compton-thick candidates at X-ray wavelengths may be confirmed according to the X-ray to mid-IR luminosity relation. We show evidence that the dusty-torus disappear when their bolometric luminosity is below L bol 10 42 erg/s. We suggest that the dominant emission at mid-IR of faint LINERs might be a combination of an elliptical galaxy host (characterised by the lack of gas), a starburst, a jet, and/or ADAF emission. Alternatively, the mid-IR emission of some of these faint LINERs could be a combination of elliptical galaxy plus carbon-rich planetary nebulae. To reconcile the Compton-thick nature of a large number of LINERs without dusty-torus signatures, we suggest that the material producing the ...

show abstract

“…Originally, PAHs were thought to appear only in those dust forming sources that are carbon-rich (Whittet 2003), but in recent years these molecules have also been observed in oxygenrich AGB and post-AGB stars, and in oxygen-rich PNe (see, e.g., Jura et al 2006;Cerrigone et al 2009;Guzmán-Ramírez et al 2011;Gielen et al 2011). These so-called mixed-chemistry PNe show PAHs and crystalline silicate features together in their infrared spectra (see e.g., Waters et al 1998;Cohen et al 1999).…”

Section: Identification Of Dust Featuresmentioning

confidence: 99%

C/O Abundance Ratios, Iron Depletions, and Infrared Dust Features in Galactic Planetary Nebulae

Delgado-Inglada

Rodríguez

2014

ApJ

View full text Add to dashboard Cite

We study the dust present in 56 Galactic planetary nebulae (PNe) through their iron depletion factors, their C/O abundance ratios (in 51 objects), and the dust features that appear in their infrared spectra (for 33 objects). Our sample objects have deep optical spectra of good quality, and most of them also have ultraviolet observations. We use these observations to derive the iron abundances and the C/O abundance ratios in a homogeneous way for all the objects. We compile detections of infrared dust features from the literature and we analyze the available Spitzer/IRS spectra. Most of the PNe have C/O ratios below one and show crystalline silicates in their infrared spectra. The PNe with silicates have C/O < 1, with the exception of Cn 1-5. Most of the PNe with dust features related to C-rich environments (SiC or the 30 μm feature usually associated to MgS) have C/O 0.8. Polycyclic aromatic hydrocarbons are detected over the full range of C/O values, including 6 objects that also show silicates. Iron abundances are low in all the objects, implying that more than 90% of their iron atoms are deposited into dust grains. The range of iron depletions in the sample covers about two orders of magnitude, and we find that the highest depletion factors are found in C-rich objects with SiC or the 30 μm feature in their infrared spectra, whereas some of the O-rich objects with silicates show the lowest depletion factors.

show abstract

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

Cited by 55 publications

References 55 publications

Chemical abundances of hot post-AGB stars

Chemical abundances of hot post-AGB stars

Nuclear obscuration in LINERs

C/O Abundance Ratios, Iron Depletions, and Infrared Dust Features in Galactic Planetary Nebulae

Contact Info

Product

Resources

About