The SAGE-Spec Spitzer Legacy programme: the life-cycle of dust and gas in the Large Magellanic Cloud - Point source classification I

Woods, Paul; Oliveira, J. M.; Kemper, F.; Loon, Jacco Th. van; Sargent, Benjamin; Matsuura, M.; Szczerba, R.; Volk, Kevin; Zijlstra, A. A.; Sloan, G. C.; Lagadec, E.; McDonald, Iain; Jones, O. C.; Gorjian, Varoujan; Kraemer, K. E.; Gielen, C.; Meixner, Margaret; Blum, Robert; Sewiło, M.; Riebel, D.; Shiao, B.; Chen, C.-H. Rosie; Indebetouw, R.; Antoniou, Vallia; Bernard, J.-P.; Cohen, Martin; Dijkstra, C.; Galametz, M.; Galliano, F.; Gordon, K. D.; Harris, Jason; Hony, S.; Hora, J. L.; Kawamura, Akiko; Lawton, Brandon; Leisenring, Jarron; Madden, S.; Marengo, Massimo; McGuire, C.; Mulia, A. J.; O’Halloran, B.; Olsen, Knut; Paladini, R.; Paradis, D.; Reach, W. T.; Rubin, D.; Sandström, Karin; Soszyński, I.; Speck, A. K.; Srinivasan, S.; Tielens, A. G. G. M.; Aarle, E. van; Dyk, Schuyler D. Van; Winckel, H. Van; Vijh, U.; Whitney, B. A.; Wilkins, Ashlee

doi:10.1111/j.1365-2966.2010.17794.x

Cited by 100 publications

(64 citation statements)

References 171 publications

(201 reference statements)

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“…Detailed spectroscopic analyses of the photospheres will allow testing of the chemical enrichment predictions of AGB theoretical models in full detail with a well constrained A90, page 26 of 45 sample of objects with known luminosities (and hence final and initial masses). Systematic IR spectroscopic surveys were defined before the construction of our catalogue, but the available Spitzer spectra (Kemper et al 2010;Woods et al 2011) form an ideal complement that is needed to fully characterise the post-AGB stars. -We have shown that light curves provide useful information on whether a post-AGB candidate is indeed a genuine post-AGB star.…”

Section: Discussionmentioning

confidence: 99%

The optically bright post-AGB population of the LMC

Aarle

Winckel

Evans

et al. 2011

A&A

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109

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Context. The detected variety in chemistry and circumstellar shell morphology of the limited sample of Galactic post-asymptotic giant branch (AGB) stars is so large that there is no consensus yet on how the different objects are linked by evolutionary channels. The evaluation is complicated by the fact that their distances and hence luminosities remain largely unknown. Aims. We construct a catalogue of the optically bright post-AGB stars in the Large Magellanic Cloud (LMC). The sample forms an ideal testbed for stellar evolution theory predictions of the final phase of low-and intermediate-mass stars, because the distance and hence luminosity and also the current and initial mass of these objects is well constrained. Methods. Via cross-correlation of the Spitzer SAGE catalogue with optical catalogues we selected a sample of LMC post-AGB candidates based on their [8] − [24] colour index and estimated luminosity. We determined the fundamental properties of the central stars of 105 of these objects using low-resolution, optical spectra that we obtained at Siding Spring Observatory and SAAO. Results. We constructed a catalogue of 70 high probability and 1337 candidate post-AGB stars that is available at the CDS. About half of the objects in our sample of post-AGB candidates show a spectral energy distribution (SED) that is indicative of a disc rather than an expanding and cooling AGB remnant. Like in the Galaxy, the disc sources are likely associated with binary evolution. Important side products of this research are catalogues of candidate young stellar objects, candidate supergiants with circumstellar dust, and discarded objects for which a spectrum was obtained. These too are available at the CDS.

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Section: Discussionmentioning

confidence: 99%

The optically bright post-AGB population of the LMC

Aarle

Winckel

Evans

et al. 2011

A&A

Self Cite

109

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“…Their broad range of colours means that C-type stars in particular are likely to be seen on either side of this colour boundary and the cut at (J − K) 0 = 1.15 mag may well represent the red limit for the majority of the M-type population rather better than the blue limit for the C-type population (Kacharov et al 2012;Sibbons et al 2014). Although in rare cases very M-type stars with (J − K) colours much redder than this have been found (Woods et al 2011), such a colour cut is appropriate for an initial estimate of the global C/M ratio, as is the aim of this work. Spectroscopic data would be required in order to refine the classification of individual stars.…”

Section: Colour Selection 331 C-and M-type Agb Starsmentioning

confidence: 99%

The AGB population in IC 1613 usingJHKphotometry

Sibbons

Ryan

Irwin

et al. 2014

A&A

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Context. A member of the Local Group, IC 1613 is a gas rich irregular dwarf galaxy that appears to have formed stars continuously over the last 10 Gyr and is relatively independent of external influences from other galaxies. Aims. This paper aims to study the spatial distribution of the asymptotic giant branch (AGB) population in IC 1613 and its metallicity. Methods. Using WFCAM on UKIRT, high quality JHK photometry of an area of 0.8 deg 2 centered on IC 1613 was obtained. The data have been used to isolate the C-and M-type components of the AGB population and using their number ratio, C/M, a global mean metallicity has been derived. The metallicity and the tip of the red giant branch magnitude (TRGB) have been studied as a function of distance from the galactic centre and as a function of azimuthal angle. Results. The TRGB has been found to be at K 0 = 18.25 ± 0.15 mag. The colour separation between the C-and M-type components of the AGB population has been located at (J − K) 0 = 1.15 ± 0.05 mag, giving a global C/M ratio of 0.52 ± 0.04 and from this an iron abundance of [Fe/H] = −1.26 ± 0.07 dex has been calculated. Conclusions. The AGB population has been detected out to a radial distance of 4.5 kpc in the de-projected plane of the galaxy. The measured TRGB is consistent with previous measurements and no significant variation is detected in the TRGB or in metallicity either with galactocentric distance or azimuthal angle.

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“…These plots demonstrate that the GRAMS grid is able to reproduce the range of observed colors for carbon star candidates. We also include sources from the SAGE-Spec study that display molecular features and/or dust signatures typical of carbon stars (Kemper et al 2010;Woods et al 2011). Only the subset of SAGE-Spec sources that had a full 5−37 μm spectrum are shown here.…”

Section: Color-magnitude and Color-color Diagramsmentioning

confidence: 99%

The mass-loss return from evolved stars to the Large Magellanic Cloud

Srinivasan

Sargent

Meixner

2011

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110

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Context. Outflows from asymptotic giant branch (AGB) and red supergiant (RSG) stars inject dust into the interstellar medium. The total rate of dust return provides an important constraint to galactic chemical evolution models. However, this requires detailed radiative transfer (RT) modeling of individual stars, which becomes impractical for large data sets. An alternative approach is to select the best-fit spectral energy distribution (SED) from a grid of dust shell models, allowing for a faster determination of the luminosities and mass-loss rates for entire samples. Aims. We have developed the Grid of RSG and AGB ModelS (GRAMS) to measure the mass-loss return from evolved stars. The models span the range of stellar, dust shell and grain properties relevant to evolved stars. The GRAMS model database will be made available to the scientific community. In this paper we present the carbon-rich AGB model grid and compare our results with photometry and spectra of Large Magellanic Cloud (LMC) carbon stars from the SAGE (Surveying the Agents of Galaxy Evolution) and SAGE-Spec programs. Methods. We generate models for spherically symmetric dust shells using the 2Dust code, with hydrostatic models for the central stars. The model photospheres have effective temperatures between 2600 and 4000 K and luminosities from ∼2000 L to ∼40 000 L . Assuming a constant expansion velocity, we explore five values of the inner radius R in of the dust shell (1.5, 3, 4.5, 7 and 12 R star ). We fix the outer radius at 1000 R in . Based on the results from our previous study, we use amorphous carbon dust mixed with 10% silicon carbide by mass. The grain size distribution follows a power-law and an exponential falloff at large sizes. The models span twenty-six values of 11.3 μm optical depth, ranging from 0.001 to 4. For each model, 2Dust calculates the output SED from 0.2 to 200 μm. Results. Over 12 000 models have dust temperatures below 1800 K. For these, we derive synthetic photometry in optical, nearinfrared and mid-infrared filters for comparison with available data. We find good agreement with magnitudes and colors observed for LMC carbon-rich and extreme AGB star candidates from the SAGE survey, as well as spectroscopically confirmed carbon stars from the SAGE-Spec study. Our models reproduce the IRAC colors of most of the extreme AGB star candidates, consistent with the expectation that a majority of these enshrouded stars have carbon-rich dust. Finally, we fit the SEDs of some well-studied carbon stars and compare the resulting luminosities and mass-loss rates with those from previous studies.

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The SAGE-Spec Spitzer Legacy programme: the life-cycle of dust and gas in the Large Magellanic Cloud - Point source classification I

Cited by 100 publications

References 171 publications

The optically bright post-AGB population of the LMC

The optically bright post-AGB population of the LMC

The AGB population in IC 1613 usingJHKphotometry

The mass-loss return from evolved stars to the Large Magellanic Cloud

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