Stellar Populations in the Large Magellanic Cloud from 2MASS

Nikolaev, Sergei; Weinberg, Martin D.

doi:10.1086/317048

Cited by 204 publications

(283 citation statements)

References 48 publications

Supporting

Mentioning

264

Contrasting

Order By: Relevance

“…From the results presented in this work we would assume a natural transition from "C-rich" to "extreme" simply caused by increasing massloss rates. Such IR-C-stars with colours as red as (J -K) ≈ 6 are also known from previous photometric investigations as, for example, the 2MASS survey of the LMC (Nikolaev & Weinberg 2000) or the Galactic bulge (Cole & Weinberg 2002).…”

Section: Extremely Reddened C Starsmentioning

confidence: 72%

Synthetic photometry for carbon-rich giants

Nowotny¹,

Aringer²,

Höfner

et al. 2013

A&A

View full text Add to dashboard Cite

Late-type giant stars in the evolutionary stage of the asymptotic giant branch increasingly lose mass via comparatively slow but dense stellar winds. Not only do these evolved red giants contribute in this way to the enrichment of the surrounding interstellar medium, but the outflows also have a substantial influence on the spectro-photometric appearance of such objects. In the case of carbon-rich atmospheric chemistries, the developing cool circumstellar envelopes contain dust grains mainly composed of amorphous carbon. With increasing mass-loss rates, this leads to more and more pronounced circumstellar reddening. With the help of model calculations we aim at reproducing the observational photometric findings for a large sample of well-characterised galactic C-type Mira variables losing mass at different rates. We used dynamic model atmospheres, describing the outer layers of C-rich Miras, which are severly affected by dynamic effects. Based on the resulting structures and under the assumptions of chemical equilibrium as well as LTE, we computed synthetic spectra and synthetic broad-band photometry (Johnson-Cousins-Glass BVRIJHKL M). A set of five representative models with different stellar parameters describes a sequence from less to more evolved objects with steadily increasing mass-loss rates. This allowed us to study the significant influence of circumstellar dust on the spectral energy distributions and the (amplitudes of) lightcurves in different filters. We tested the photometric properties (mean NIR magnitudes, colours, and amplitudes) and other characteristics of the models (mass-loss rates, periods, and bolometric corrections) by comparing these with the corresponding observational data adopted from the literature. Using different kinds of diagrams we illustrate where the models are located in a supposed evolutionary sequence defined by observed C-type Mira samples. Based on comparisons of galactic targets with empirical relations derived for C stars in the Large Magellanic Cloud we discuss the relevance of metallicity and excess carbon (C-O) for the development of dust-driven winds. Having investigated the dynamic model atmospheres from different (mainly photometric) perspectives, we conclude that our modelling approach (meaning the combination of numerical method and a suitable choice of model parameters) is able to describe C-rich long-period variables over a wide range of mass-loss rates, i.e., from moderately pulsating objects without any dusty wind to highly dust-enshrouded Carbon Miras. Thus, we can trace the observed sequence of C-type Miras, which is mainly determined by the mass loss.

show abstract

Section: Extremely Reddened C Starsmentioning

confidence: 72%

Synthetic photometry for carbon-rich giants

Nowotny¹,

Aringer²,

Höfner

et al. 2013

A&A

View full text Add to dashboard Cite

show abstract

“…VMC will also provide CMDs involving the J passband, and their use in the SFH analysis can reduce the final errors. Another factor to be considered in the final analysis is that for old ages the SFR(t) is expected to vary very smoothly across the LMC, as indicated for instance by Cioni et al (2000) and Nikolaev & Weinberg (2000). This large-scale correlation in the old SFR(t) may be used as an additional constraint during the SFH-recovery and may help to reduce the errors in the SFR(t) at all ages.…”

Section: Discussionmentioning

confidence: 97%

Recovery of the star formation history of the LMC from the VISTA survey of the Magellanic system

Kerber

Girardi

Rubele

et al. 2009

A&A

View full text Add to dashboard Cite

The VISTA near infrared survey of the Magellanic System (VMC) will provide deep Y JK s photometry reaching stars in the oldest turn-off point throughout the Magellanic Clouds (MCs). As part of the preparation for the survey, we aim to access the accuracy in the star formation history (SFH) that can be expected from VMC data, in particular for the Large Magellanic Cloud (LMC). To this aim, we first simulate VMC images containing not only the LMC stellar populations but also the foreground Milky Way (MW) stars and background galaxies. The simulations cover the whole range of density of LMC field stars. We then perform aperture photometry over these simulated images, access the expected levels of photometric errors and incompleteness, and apply the classical technique of SFH-recovery based on the reconstruction of colour-magnitude diagrams (CMD) via the minimisation of a chi-squared-like statistics. We verify that the foreground MW stars are accurately recovered by the minimisation algorithms, whereas the background galaxies can be largely eliminated from the CMD analysis due to their particular colours and morphologies. We then evaluate the expected errors in the recovered star formation rate as a function of stellar age, SFR(t), starting from models with a known age-metallicity relation (AMR). It turns out that, for a given sky area, the random errors for ages older than ∼0.4 Gyr seem to be independent of the crowding. This can be explained by a counterbalancing effect between the loss of stars from a decrease in the completeness and the gain of stars from an increase in the stellar density. For a spatial resolution of ∼0.1 deg 2 , the random errors in SFR(t) will be below 20% for this wide range of ages. On the other hand, due to the lower stellar statistics for stars younger than ∼0.4 Gyr, the outer LMC regions will require larger areas to achieve the same level of accuracy in the SFR(t). If we consider the AMR as unknown, the SFHrecovery algorithm is able to accurately recover the input AMR, at the price of an increase of random errors in the SFR(t) by a factor of about 2.5. Experiments of SFH-recovery performed for varying distance modulus and reddening indicate that these parameters can be determined with (relative) accuracies of Δ(m− M) 0 ∼ 0.02 mag and ΔE B−V ∼ 0.01 mag, for each individual field over the LMC. The propagation of these errors in the SFR(t) implies systematic errors below 30%. This level of accuracy in the SFR(t) can reveal significant imprints in the dynamical evolution of this unique and nearby stellar system, as well as possible signatures of the past interaction between the MCs and the MW.

show abstract

“…The detailed stellar population study for the LMC based on 2MASS data by Nikolaev (2000) shows various bright features analyzed in the CMD of the LMC, but mainly deals with high-mass objects as the detection limit of 2MASS corresponds to point sources brighter than m Ks = 16 mag, thus no low-mass LMC star formation information can be derived from the 2MASS catalog. It can easily be seen that the observations described and analyzed in this paper offered the required fainter apparent magnitudes needed to answer the question of "starless"-ness in the class of apparently non-star forming GMCs.…”

Section: Comparing the Achieved Range Of Magnitudes With Other Lmc Sumentioning

confidence: 99%

Star formation in the LMC: Comparative CCD observations of young stellar populations in two giant molecular clouds

Ruppert

Zinnecker

2009

Astron Nachr

View full text Add to dashboard Cite

This work deals with a CCD imaging study at optical and near-infrared wavelength of two giant molecular clouds (plus a control field) in the southern region of the Large Magellanic Cloud, one of which shows multiple signs of star formation, whereas the other does not. The observational data from VLT FORS2 (R band) and NTT SOFI (Ks band) have been analyzed to derive luminosity functions and color-magnitude diagrams. The young stellar content of these two giant molecular clouds is compared and confirmed to be different, in the sense that the apparently "starless" cloud has so far formed only low-luminosity, low-mass stars (fainter than mKs ∼ 16.5 mag, not seen by 2MASS), while the other cloud has formed both faint low-mass and luminous high-mass stars. The surface density excess of low-luminosity stars (∼ 2 per square arcmin) in the "starless" cloud with respect to the control field is about 20% whereas the excess is about a factor of 3 in the known star-forming cloud. The difference may be explained theoretically by the gravo-turbulent evolution of giant molecular clouds, one being younger and less centrally concentrated than the other.

show abstract

Stellar Populations in the Large Magellanic Cloud from 2MASS

Cited by 204 publications

References 48 publications

Synthetic photometry for carbon-rich giants

Synthetic photometry for carbon-rich giants

Recovery of the star formation history of the LMC from the VISTA survey of the Magellanic system

Star formation in the LMC: Comparative CCD observations of young stellar populations in two giant molecular clouds

Contact Info

Product

Resources

About