Spectroscopic survey of post-AGB star candidates

Pereira, C. B.; Miranda, L. F.

doi:10.1051/0004-6361:20054529

Cited by 21 publications

(24 citation statements)

References 35 publications

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“…Our work complements recent optical spectroscopic surveys of PPNs/PNs (e.g., Suárez et al 2006;Pereira & Miranda 2007) by providing deep, high spectral resolution spectra covering a wide wavelength range. Here, we focus on the characterization and analysis of the different types of H profiles and their correlation with several stellar and envelope parameters.…”

Section: Introductionmentioning

confidence: 57%

Echelle Long‐Slit Optical Spectroscopy of Evolved Stars

Contreras

Sahai²,

Paz

et al. 2008

Astrophysical Journal Supplement Series, The

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We present echelle long-slit optical spectra of a sample of objects evolving off the asymptotic giant branch (AGB), most of them in the preplanetary nebula ( PPN ) phase, obtained with the ESI and MIKE spectrographs at the 10 m Keck II and 6.5 m Magellan-I telescopes, respectively. The total wavelength range covered with ESI (MIKE) is $3900Y10900 8 ($3600Y7200 8). In this paper, we focus our analysis mainly on the H profiles. Prominent H emission is detected in half of the objects, most of which show broad H wings (with total widths of up to $4000 km s À1 ). In the majority of the H -emission sources, fast, post-AGB winds are revealed by P-Cygni profiles. In $37% of the objects H is observed in absorption. In almost all cases, the absorption profile is partially filled with emission, leading to complex, structured profiles that are interpreted as an indication of incipient post-AGB mass loss. The rest of the objects ($13%) are H nondetections. We investigate correlations between the H profile and different stellar and envelope parameters. All sources in which H is seen mainly in absorption have F-G type central stars, whereas sources with intense H emission span a larger range of spectral types from O to G, with a relative maximum around B, and also including very late C types. Shocks may be an important excitation/ionization agent of the close stellar surroundings for objects with late type central stars. Sources with pure emission or P Cygni H profiles have larger J À K color excess than objects with H mainly in absorption, which suggests the presence of warm dust near the star in the former. The two classes of profile sources also segregate in the IRAS color-color diagram in a way that intense H -emitters have dust grains with a larger range of temperatures. Spectral classification of the central stars in our sample is presented. For a subsample (13 objects), the stellar luminosity has been derived from the analysis of the O i 7771Y7775 8 infrared triplet. The location in the HR diagram of most of these targets, which represent $30% of the whole sample, is consistent with relatively high final (and, presumably, initial) masses in the range M f $ 0:6 Y0:9 M (M i $ 3Y 8 M ).

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Section: Introductionmentioning

confidence: 57%

Echelle Long‐Slit Optical Spectroscopy of Evolved Stars

Contreras

Sahai²,

Paz

et al. 2008

Astrophysical Journal Supplement Series, The

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“…47, IRAS 19336- Fig. 1 in Pereira & Miranda 2007). IRAS 19336-0400 was first identified as a emission-line object by Stephenson & Sanduleak (1977) and later spectroscopically observed by Downes & Keyes (1988).…”

Section: Introductionmentioning

confidence: 99%

“…The other low-excitation object, IRAS 19336-0400, entered in our analysis in the framework of our spectroscopic survey of post-AGB candidates (Pereira & Miranda 2007). Our aim in that survey was to present and discuss the spectra of several candidates to post-AGB stars, in order to establish their nature and identify new post-AGB stars.…”

Section: Introductionmentioning

confidence: 99%

Identification of PN G232.0+05.7 as a new halo planetary nebula and of IRAS 19336-0400 as a new type III planetary nebula

Pereira

Miranda

2007

A&A

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Aims. We determined the nature and Peimbert type of two low-excitation planetary nebulae, PNG 232.0+05.7 and IRAS 19336-0400. Methods. We used low resolution optical spectroscopy in the range 3200-9000 Å. Results. We derived line intensities, reddening, physical conditions (electron density and temperature) and ionic and elemental abundances. Based on the abundance analysis and its radial velocity we conclude that PNG 232.0+05.7 is a halo planetary nebulae. This discovery thus adds this object to the sample of ten known halo planetary nebulae. IRAS 19336-0400 is probably a type III planetary nebulae, as strongly suggested by its abundances and high radial velocity, although this conclusion awaits a better estimation of its distance.Key words. planetary nebulae: individual: PN G232.0+05.7 -planetary nebulae: individual: IRAS 19336+0400 IntroductionThe two objects analyzed in this work, PN G232.0+05.7 and IRAS 19336-0400, came to our attention for different reasons. In the case of PN G232.0+05.7 we were looking for whether in Table 1 of Sanduleak & Stephenson (1972) an object classified as a very low-excitation nebula, would have any information about the presence of absorption features in its spectrum. If so, this object could be a good target to be labelled as a "peculiar planetary nebula" as those singled out by Lutz (1977). In her study, she realize that there is a small group of objects in the Catalogue of Planetary Nebulae (Perek & Kohoutek 1967) that appear peculiar because they have nebular emission lines in combination with the absorption spectrum of a cool (spectral type A to K) central star.To illustrate the connection between an object classified as a very low-excitation compact nebula and one that could might be called as "peculiar planetary nebula", according to Lutz (1977), we could mention Hen 3-1312 (=SaSt 2-12, Sanduleak & Stephenson 1972). Pereira (2004) shows that Hen 3-1312 has a continuum spectrum of a F-type star with emission lines. Another example of a very low-excitation compact nebula, but instead, with a continuum of a hot star, is provided by the object Hen 2-138 (=SaSt 2-10, its spectrum is shown in Fig. 1).Since our primary goal is to find an object which presents in its spectrum emission lines in combination with the absorption features of a cool star, we first need to observe spectroscopically a candidate in order to set what kind of very low-excitation compact nebula we are going to investigate. Therefore, we searched again Table 1 of Sanduleak & Stephenson (1972) and found that Stephenson & Sanduleak (1977) and later spectroscopically observed by Downes & Keyes (1988). Its spectrum is described by Van de Steene et al. (1996) and Parthasarathy et al. (2000). They both suggest that IRAS 19336-0400 is a young and low-excitation planetary nebula with a B1 supergiant central star.In this paper we present an abundance analysis of these two low-excitation objects, based on low resolution optical spectroscopy, carried out with the aim of investigating their nature in detail. ...

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“…Therefore, the use of the IRAS two-color diagram provides an Postdoctoral Research Fellow. invaluable strategy that has resulted in a number of catalogs of young PNe and their immediate precursors, post-AGB stars (e.g. Preite-Martinez 1988;Pottasch et al 1988;van der Veen et al 1989;Ratag et al 1990;Hu et al 1993;Pereira & Miranda 2007). Recently, Suárez et al (2006) presented a comprehensive optical spectroscopic atlas of post-AGB stars and young PNe selected from the IRAS Point Source Catalogue.…”

Section: Introductionmentioning

confidence: 99%

Searching for heavily obscured post-AGB stars and planetary nebulae

Ramos-Larios

Guerrero

Suárez

et al. 2009

A&A

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Context. The transition from the asymptotic giant branch (AGB) to the planetary nebula (PN) phase is critical in the shaping of PNe. It has been suggested that the most asymmetric PNe are the descendants of massive AGB stars. Since these AGB stars are believed to have evolved into heavily obscured post-AGB stars and PNe, the compilation of a sample of bona fide obscured post-AGB stars and PNe is important for understanding the formation of asymmetric PNe. Aims. We aim to identify and characterize a large number of post-AGB stars and PNe in the IR and to assess their degree of optical obscuration. The improved positions will enable future detailed studies to determine their true nature, whereas the optical and IR properties can be used to investigate their spectral behavior. Methods. We used 2MASS, Spitzer GLIMPSE, MSX, and IRAS data in search of the near-IR counterparts of a sample of 165 presumably obscured IRAS post-AGB and PN candidates, and DSS red images to identify the optical counterparts among the objects detected in the near-IR. The IR spectral energy distributions (SEDs) in the wavelength range from 1 μm to 100 μm of the sources with unambiguous near-IR counterparts were analyzed using appropriate color−color diagrams. Results. We have identified the near-IR counterparts of 119 sources out of the 165 IRAS post-AGB and PN candidates in our sample. The improved astrometric coordinates of these sources have allowed us to find optical counterparts for 59 of them, yielding a reduced sample of 60 optically obscured post-AGB star and PN candidates. Among the 119 sources with near-IR counterparts, only 80 have unambiguous identifications in the 2MASS Point Source Catalogue. For these sources, we find that objects with and without optical counterparts, while having similar mid-and far-IR colors, are segregated in color−color diagrams that use the near-IR J band to compute one of the colors.

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Spectroscopic survey of post-AGB star candidates

Cited by 21 publications

References 35 publications

Echelle Long‐Slit Optical Spectroscopy of Evolved Stars

Echelle Long‐Slit Optical Spectroscopy of Evolved Stars

Identification of PN G232.0+05.7 as a new halo planetary nebula and of IRAS 19336-0400 as a new type III planetary nebula

Searching for heavily obscured post-AGB stars and planetary nebulae

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