An infrared study of galactic OH/IR stars

Jiménez-Esteban, F. M.; Agudo-Mérida, L.; Engels, D.; García-Lario, P.

doi:10.1051/0004-6361:20041709

Cited by 20 publications

(14 citation statements)

References 28 publications

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“…We find a similarity between the "lower branch" stars and the sample of Galactic OH/IR stars in Jiménez-Esteban et al (2005). These authors conclude that the luminosity and color distribution observed could be explained as the result of a combined emission of a cool star (T ∼ 2500 K) and a much cooler dust shell (T < 800 K).…”

Section: Nicer Extinction Mapsupporting

confidence: 72%

2MASS wide field extinction maps

Lombardi

Alves²,

Lada

2006

A&A

224

350

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Aims. We present a 8• × 6• , high resolution extinction map of the Pipe nebula using 4.5 million stars from the Two Micron All Sky Survey (2MASS) point source catalog. Methods. The use of N , A&A, 377, 1023, a robust and optimal technique to map the dust column density, allows us to detect a A V = 0.5 mag extinction at a 3-σ level with a 1 arcmin resolution. Results. (i) We find for the Pipe nebula a normal reddening law,We measure the cloud distance using Hipparchos and Tycho parallaxes, and obtain 130 +24 −58 pc. This, together with the total estimated mass, 10 4 M , makes the Pipe the closest massive cloud complex to Earth. (iii) We compare the N extinction map to the NANTEN 12 CO observations and derive with unprecedented accuracy the relationship between the near-infrared extinction and the 12 CO column density and hence (indirectly) the 12 CO X-factor, that we estimate to be 2.91 × 10 20 cmWe identify approximately 1500 OH/IR stars located within the Galactic bulge in the direction of the Pipe field. This represents a significant increase of the known numbers of such stars in the Galaxy. Conclusions. Our analysis confirms the power and simplicity of the color excess technique to study molecular clouds. The comparison with the NANTEN 12 CO data corroborates the insensitivity of CO observations to low column densities (up to approximately 2 mag in A V ), and shows also an irreducible uncertainty in the dust-CO correlation of about 1 mag of visual extinction.

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Section: Nicer Extinction Mapsupporting

confidence: 72%

2MASS wide field extinction maps

Lombardi

Alves²,

Lada

2006

A&A

224

350

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“…1 also shows the emission from the thermal complex G35.5−0.0. The two compact sources within and near G35.6−0.4 are IRAS 18551+0159 (near ) and IRAS 18554+0203 (near ), which are a candidate post‐asymptotic giant branch star and a planetary nebula, respectively (see Condon, Kaplan & Terzian 1999; Jiménez‐Esteban et al 2005; Parker et al 2006; Cohen et al 2007; Kwok et al 2008 and references therein). IRAS 18551+0159 and IRAS 18554+0203 have ≈ 0.117 and 0.096 Jy at 1.4 GHz (Condon, Kaplan, & Terzian).…”

Section: Observationsmentioning

confidence: 98%

Re-identification of G35.6−0.4 as a supernova remnant

Green¹

2009

Monthly Notices of the Royal Astronomical Society

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G35.6−0.4 is an extended radio source in the Galactic plane which has previously been identified as either a supernova remnant or an H ii region. Observations from the Very Large Array Galactic Plane Survey at 1.4 GHz with a resolution of 1 arcmin allow the extent of G35.6−0.4 to be defined for the first time. Comparison with other radio survey observations show that this source has a non‐thermal spectral index, with S∝ν−0.47±0.07. G35.6−0.4 does not have obvious associated infrared emission, so it is identified as a Galactic supernova remnant, not an H ii region. It is ≈15 × 11 arcmin2 in extent, showing partial limb brightening.

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“…The high value of this index implies that all sources should be large-amplitude variables. By comparison with the colours of the "Arecibo sample" of O-rich AGB stars (Jiménez-Esteban et al 2005), they concluded that their sample of extremely reddened IRAS sources was also mainly made up of O-rich AGB stars highly obscured by their CSEs. To define the GB sample presented here, we selected the extremely reddened IRAS sources from Jiménez-Esteban et al (2006) with angular distances ≤10 • from the Galactic centre.…”

Section: The Samplementioning

confidence: 99%

Study of extremely reddened AGB stars in the Galactic bulge

Jiménez-Esteban

Engels

2015

A&A

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Context. Extremely reddened asymptotic giant branch stars (AGB) lose mass at high rates of >10 −5 M yr −1 . This is the very last stage of AGB evolution, in which stars in the mass range ∼2.0−4.0 M (for solar metallicity) should have been converted to C stars already. The extremely reddened AGB stars in the Galactic bulge are however predominantly O-rich, implying that they might be either low-mass stars or stars at the upper end of the AGB mass range. Aims. Our goal is to determine the mass range of the most reddened AGB stars in the Galactic bulge. Methods. Using Virtual Observatory tools, we constructed spectral energy distributions of a sample of 37 evolved stars in the Galactic bulge with extremely red IRAS colours. We fitted DUSTY models to the observational data to infer the bolometric fluxes. Applying individual corrections for interstellar extinction and adopting a common distance, we determined luminosities and mass-loss rates, and inferred the progenitor mass range from comparisons with AGB evolutionary models. Results. The observed spectral energy distributions are consistent with a classification as reddened AGB stars, except for two stars, which are proto-planetary nebula candidates. For the AGB stars, we found luminosities in the range ∼3000−30 000 L and mass-loss rates ∼10 −5 −3 × 10 −4 M yr −1 . The corresponding mass range is ∼1.1−6.0 M assuming solar metallicity. Conclusions. Contrary to the predictions of the evolutionary models, the luminosity distribution is continuous, with many O-rich AGB stars in the mass range in which they should have been converted into C stars already. We suspect that bulge AGB stars have higher than solar metallicity and therefore may avoid the conversion to C-rich. The presence of low-mass stars in the sample shows that their termination of the AGB evolution also occurs during a final phase of very high mass-loss rate, leading to optically thick circumstellar shells.

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An infrared study of galactic OH/IR stars

Cited by 20 publications

References 28 publications

2MASS wide field extinction maps

2MASS wide field extinction maps

Re-identification of G35.6−0.4 as a supernova remnant

Study of extremely reddened AGB stars in the Galactic bulge

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