The chemical composition of the protoplanetary nebula candidate HD 179821

Začs, L.; Клочкова, В. Г.; Панчук, В. Е.; Spelmanis, R.

doi:10.1093/mnras/282.4.1171

Cited by 42 publications

(59 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In fact, the center of the H absorption component and that attributed to the Ti i line yield a very similar value of the systemic velocity, V LSR ¼ 111 and 104 km s À1 , respectively, in good agreement with earlier results from other absorption lines and CO measurements (e.g., Reddy & Hrivnak 1999;Bujarrabal et al 2001 and references therein). Začs et al (1996) also observed a doublepeaked emission component and a narrow absorption core in the H profile of this object, i.e., a shell profile, however, in our spectrum the red emission component is stronger than the blue one, in contrast to what these authors found. Moreover, the velocity difference between the two emission peaks measured by us, $145 km s À1 , is larger than that observed by Začs et al (1996) $128 km s À1 .…”

Section: Variability Of the H Profilecontrasting

confidence: 92%

“…3). There is another absorption feature blueward of H (k obs ¼ 6561:1 8) that is most likely the Ti i k6559.57 line as suggested by Začs et al (1996). In fact, the center of the H absorption component and that attributed to the Ti i line yield a very similar value of the systemic velocity, V LSR ¼ 111 and 104 km s À1 , respectively, in good agreement with earlier results from other absorption lines and CO measurements (e.g., Reddy & Hrivnak 1999;Bujarrabal et al 2001 and references therein).…”

Section: Variability Of the H Profilementioning

confidence: 89%

“…IRAS 19114+0002 has been classified as either a PPN descended from low-or intermediate-mass progenitor (Reddy & Hrivnak 1999) or a yellow hypergiant (YHG) descended from a massive ($30 M ) Population I supergiant (e.g., Jura & Werner 1999;Castro-Carrizo et al 2007). YHGs are believed to follow an evolutionary path similar to that of PPNs; they undergo a strong Klochkova et al 1999;(6) Klochkova et al 2002;(7) Loup et al 1993;(8) Lowe & Gledhill 2007;(9) Mauron & Huggins 2006;(10) Nyman et al 1998;(11) Oppenheimer & Davé 2006;(12) Reddy & Hrivnak 1999;(13) Sahai et al 2003;(14) Sahai et al 2005;(15) Sahai et al 2007a;(16) Sahai et al 2008;(17) R. Sahai et al in preparation ( HST GO 9463, 10185);(18) Sánchez Contreras et al 2006a, 2006b(19) Schmidt et al 2002;(20) Sevenster 2002;(21) Su et al 2001;(22) Suárez et al 2006;(23) Szczerba et al 2007: The Torun Catalogue of Galactic Post-AGB and Related Objects; (24) Ueta et al 2000;(25) Ueta et al 2007;(26) van der Veen et al 1989;(27) Začs et al 1996. mass-loss process leading to massive CSEs...…”

Section: The Samplementioning

confidence: 99%

See 2 more Smart Citations

Echelle Long‐Slit Optical Spectroscopy of Evolved Stars

Contreras

Sahai²,

Paz

et al. 2008

Astrophysical Journal Supplement Series, The

View full text Add to dashboard Cite

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 ).

show abstract

Section: Variability Of the H Profilecontrasting

confidence: 92%

Section: Variability Of the H Profilementioning

confidence: 89%

Section: The Samplementioning

confidence: 99%

See 1 more Smart Citation

Echelle Long‐Slit Optical Spectroscopy of Evolved Stars

Contreras

Sahai²,

Paz

et al. 2008

Astrophysical Journal Supplement Series, The

View full text Add to dashboard Cite

show abstract

“…database permitted to identify various rare-earth-element lines contributing to the absorption feature at 6708 Å in the spectra of the s-process element enriched stars. Thus, the line at 6708.099 Å in the spectra of the low-mass post-AGB stars enriched in s-process elements considered previously as a "shifted Li line" (Začs et al 1995;Reddy et al 1997Reddy et al , 1999Reddy et al , 2002 was identified as the Ce ii transition at 6708.099 Å (Reyniers et al 2002). Both stars, HD 10613 and BD+04 • 2466, clearly show this line in the spectra.…”

Section: LImentioning

confidence: 65%

High-resolution spectroscopic observations of two chemically peculiar metal-poor stars: HD 10613 and BD+04°2466

Pereira

Драке²

2009

A&A

View full text Add to dashboard Cite

Aims. We determined the atmospheric parameters and abundance pattern of two chemically peculiar metal-poor stars: HD 10613 and BD+04 • 2466 in order to better understand their evolutionary state and the nature of the s-element enhancement of these stars. Methods. We used high resolution optical spectroscopy. Atmospheric parameters and abundances were determined in the localthermodynamic-equilibrium model atmospheres of Kurucz using the spectral analysis code MOOG. • 2466 the abundance of lead is in agreement with predictions from AGB models. Due to the low luminosity of these two stars, their observed s-process overabundance is better explained by mass-transfer in the past from an AGB star.

show abstract

“…In general three classes of Li rich evolved (AGB and post-AGB) stars can be distinguished: (1) the luminous "hot bottom burning" (HBB) S-type AGB stars in the Clouds (Plez et al 1993, Smith et al 1995 and the Galaxy (García-Lario et al 1999); (2) galactic low-mass C stars (Abia et al 1993;Abia & Isern 1997 which are mostly J-type and (3) 4 metal-poor low-mass post-3rd dredge-up objects being IRAS 22272+5435 (Začs et al 1995), IRAS 05341+0852 (Reddy et al 1997), IRAS Z02229+6208 and IRAS 07430+1115 (Reddy et al 1999). Only for the HBB stars, Li production is supported by the models via the 7 Be-transport mechanism (Cameron & Fowler 1971).…”

Section: Lithium In Hd 172481mentioning

confidence: 99%

The Very Lithium Rich Post-AGB SB2 Binary HD 172481

Reyniers¹,

Winckel²

2001

Post-Agb Objects as a Phase of Stellar Evolution

View full text Add to dashboard Cite

Double lined spectroscopic binaries in an evolved stage of evolution are expected to be extremely rare since they must consist of equally luminous and thus almost equally evolved objects, which requires an extremely similar initial mass. In this contribution we discuss such rare double evolved SB2 system: HD 172481. This binary includes an Ftype post-AGB object and an M-type AGB companion. The spectrum shows a surprisingly strong Li I 670.8 nm line with an equivalent width of W λ = 54 mÅ, yielding a lithium abundance of log ǫ(Li) = 3.6. Several explanations for this huge lithium content are explored. HD 172481 IN THE POST-AGB SAMPLEIn the course of our ongoing program to study the chemical composition of post-AGB stars (see Van Winckel, this volume), high resolution, high signal-to-noise spectra were taken of the F2Ia supergiant HD 172481. This star was previously selected as a candidate post-AGB star by Oudmaijer et al. (1992) because of its far infrared excess and its high galactic latitude (b = −10.37 • ). OBSERVATIONAL DATAOur photometric data consist of 54 data points in the Geneva photometric system between 1989 and 1996, near-IR JHKLM photometry taken with the ESO 1m telescope in 1992 and the IRAS-fluxes. 62 radial velocity measurements were obtained with the CORAVEL radial velocity spectrometer (Danish 1.5m telescope, La Silla, Chile) between 1983 and 1997 and 4 recent measurements with the CORALIE spectrograph (Euler telescope, La Silla, Chile). 5 high resolution, high signal-to-1

show abstract

The chemical composition of the protoplanetary nebula candidate HD 179821

Cited by 42 publications

References 0 publications

Echelle Long‐Slit Optical Spectroscopy of Evolved Stars

Echelle Long‐Slit Optical Spectroscopy of Evolved Stars

High-resolution spectroscopic observations of two chemically peculiar metal-poor stars: HD 10613 and BD+04°2466

The Very Lithium Rich Post-AGB SB2 Binary HD 172481

Contact Info

Product

Resources

About