Study of extremely reddened AGB stars in the Galactic bulge

Jiménez-Esteban, F. M.; Engels, D.

doi:10.1051/0004-6361/201424609

Cited by 14 publications

(9 citation statements)

References 73 publications

(123 reference statements)

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“…We derive similar luminosities and mass loss rates, yet find few cases where our best fit models have similar optical depths. It was suggested by Jiménez-Esteban & Engels (2015) that the existence of these oxygen-rich Galactic Bulge sources can be explained if they have metallicities at or above solar metallicity, which is consistent with our derived gas-to-dust ratios. Our Galactic sources may be alphaenhanced which would increase the abundance of elements like Si, Ti and Mg, and thus increase dust production.…”

Section: Gas-to-dust Ratios In the Lmcsupporting

confidence: 92%

The wind speeds, dust content, and mass-loss rates of evolved AGB and RSG stars at varying metallicity

Goldman

Loon

Zijlstra

et al. 2016

Mon. Not. R. Astron. Soc.

146

118

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We present the results of our survey of 1612 MHz circumstellar OH maser emission from asymptotic giant branch (AGB) stars and red supergiants (RSGs) in the Large Magellanic Cloud. We have discovered four new circumstellar maser sources in the LMC, and increased the number of reliable wind speeds from IR stars in the LMC from 5 to 13. Using our new wind speeds, as well as those from Galactic sources, we have derived an updated relation for dust driven winds: v exp ∝ ZL 0.4 . We compare the sub-solar metallicity LMC OH/IR stars with carefully selected samples of more metal-rich OH/IR stars, also at known distances, in the Galactic Centre and Galactic Bulge. For 8 of the Bulge stars we derive pulsation periods for the first time, using near-IR photometry from the VVV survey. We have modeled our LMC OH/IR stars and developed an empirical method of deriving gas-to-dust ratios and mass loss rates by scaling the models to the results from maser profiles. We have done this also for samples in the Galactic Centre and Bulge and derived a new mass loss prescription that includes luminosity, pulsation period, and gas-to-dust ra-tioṀ = 1.06 +3.5 −0.8 ·10 −5 (L/10 4 L ) 0.9±0.1 (P/500 d) 0.75±0.3 (r gd /200) −0.03±0.07 M yr −1 . The tightest correlation is found between mass loss rate and luminosity. We find that the gas-to-dust ratio has little effect on the mass loss of oxygen-rich AGB stars and RSGs within the Galaxy and the LMC. This suggests that mass loss of oxygen-rich AGB stars and RSGs is (nearly) independent of metallicity between a half and twice solar.

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Section: Gas-to-dust Ratios In the Lmcsupporting

confidence: 92%

The wind speeds, dust content, and mass-loss rates of evolved AGB and RSG stars at varying metallicity

Goldman

Loon

Zijlstra

et al. 2016

Mon. Not. R. Astron. Soc.

146

118

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“…Uttenthaler et al (2007) stated that this required third dredge-up, and thus relatively large initial masses ( ) and young ages for a sizable fraction of the bulge stellar population. Finally, Jiménez-Esteban & Engels (2015) has recently fit evolutionary and dust models to multi-wavelength observations of the reddest Galactic bulge asymptotic giant branch stars, and estimated an initial mass range of .…”

Section: Arguments For An Intermediate-age Bulge: Asymptotic Giant Brmentioning

confidence: 99%

The Controversial Star-Formation History and Helium Enrichment of the Milky Way Bulge

Nataf

2016

Publ. Astron. Soc. Aust.

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The stellar population of the Milky Way bulge is thoroughly studied, with a plethora of measurements from virtually the full suite of instruments available to astronomers. It is thus perhaps surprising that alongside well-established results lies some substantial uncertainty in its star-formation history. Cosmological models predict the bulge to host the Galaxy's oldest stars for [Fe/H] −1, and this is demonstrated by RR Lyrae stars and globular cluster observations. There is consensus that bulge stars with [Fe/H] 0 are older than t ≈ 10 Gyr. However, at super-solar metallicity, there is a substantial unresolved discrepancy. Data from spectroscopic measurements of the main-sequence turnoff and subgiant branch, the abundances of asymptotic giant branch stars, the period distribution of Mira variables, the chemistry and central-star masses of planetary nebulae, all suggest a substantial intermediate-age population (t ≈ 3 Gyr). This is in conflict with predictions from cosmologically-motivated chemical evolution models and photometric studies of the main-sequence turnoff region, which both suggest virtually no stars younger than t ≈ 8 Gyr. A possible resolution to this conflict is enhanced helium-enrichment, as this would shift nearly all of the age estimates in the direction of decreasing discrepancy. Enhanced helium-enrichment is also arguably suggested by measurements of the red giant branch bump and the R-parameter.

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“…Only a NIR mission would be able to really characterize these stars and to ultimately define their period-luminosity relation. With such a new mission it would be also possible to study the effect of the different metallicities in the bulge and the disc on the period-luminosity relation [117], so they could be used as standard candles improving the distance scale.…”

Section: Stellar Variabilitymentioning

confidence: 99%

All-sky visible and near infrared space astrometry

et al. 2021

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The era of all-sky space astrometry began with the Hipparcos mission in 1989 and provided the first very accurate catalogue of apparent magnitudes, positions, parallaxes and proper motions of 120 000 bright stars at the milliarcsec (or milliarcsec per year) accuracy level. Hipparcos has now been superseded by the results of the Gaia mission. The second Gaia data release contained astrometric data for almost 1.7 billion sources with tens of microarcsec (or microarcsec per year) accuracy in a vast volume of the Milky Way and future data releases will further improve on this. Gaia has just completed its nominal 5-year mission (July 2019), but is expected to continue in operations for an extended period of an additional 5 years through to mid 2024. Its final catalogue to be released $\sim $ ∼ 2027, will provide astrometry for $\sim $ ∼ 2 billion sources, with astrometric precisions reaching 10 microarcsec. Why is accurate astrometry so important? The answer is that it provides fundamental data which underpin much of modern observational astronomy as will be detailed in this White Paper. All-sky visible and Near-InfraRed (NIR) astrometry with a wavelength cutoff in the K-band is not just focused on a single or small number of key science cases. Instead, it is extremely broad, answering key science questions in nearly every branch of astronomy while also providing a dense and accurate visible-NIR reference frame needed for future astronomy facilities.

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Study of extremely reddened AGB stars in the Galactic bulge

Cited by 14 publications

References 73 publications

The wind speeds, dust content, and mass-loss rates of evolved AGB and RSG stars at varying metallicity

The wind speeds, dust content, and mass-loss rates of evolved AGB and RSG stars at varying metallicity

The Controversial Star-Formation History and Helium Enrichment of the Milky Way Bulge

All-sky visible and near infrared space astrometry

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