Dissecting 30 Doradus: Optical and Near Infrared Star Formation History of the starburst cluster NGC2070 from the Hubble Tarantula Treasury Project

AbstractI will present new results on the star formation history of 30 Doradus in the Large Magellanic Cloud based on the panchromatic imaging survey Hubble Tarantula Treasury Project (HTTP). Here the focus is on the starburst cluster NGC2070. The star formation history is derived by comparing the deepest ever optical and NIR color-magnitude diagrams (CMDs) with state-of-the-art synthetic CMDs generated with the latest PARSEC models, which include all stellar phases from pre-main sequence to post-main sequence. For the first time in this region we are able to measure the star formation using intermediate and low mass stars simultaneously. Our results suggest that NGC2070 experienced a prolonged activity. I will discuss the detailed star formation history, initial mass function and reddening distribution.

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Recovering the star formation history of galaxies through spectral fitting: Current challenges

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320001647 ◽

2019 ◽

Vol 15 (S359) ◽

pp. 386-390

Author(s):

Lucimara P. Martins

Keyword(s):

Star Formation ◽

Mass Function ◽

Initial Mass Function ◽

Star Formation History ◽

Stellar Spectra ◽

Spectral Fitting ◽

Formation History ◽

History Of ◽

Nearby Galaxies ◽

Extract Information

AbstractWith the exception of some nearby galaxies, we cannot resolve stars individually. To recover the galaxies star formation history (SFH), the challenge is to extract information from their integrated spectrum. A widely used tool is the full spectral fitting technique. This consists of combining simple stellar populations (SSPs) of different ages and metallicities to match the integrated spectrum. This technique works well for optical spectra, for metallicities near solar and chemical histories not much different from our Galaxy. For everything else there is room for improvement. With telescopes being able to explore further and further away, and beyond the optical, the improvement of this type of tool is crucial. SSPs use as ingredients isochrones, an initial mass function, and a library of stellar spectra. My focus are the stellar libraries, key ingredient for SSPs. Here I talk about the latest developments of stellar libraries, how they influence the SSPs and how to improve them.

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Breaking the age–metallicity degeneracy: The metallicity distribution and star formation history of the Large Magellanic Cloud

Proceedings of the International Astronomical Union ◽

10.1017/s174392130802855x ◽

2008 ◽

Vol 4 (S256) ◽

pp. 263-268 ◽

Cited By ~ 4

Author(s):

Andrew A. Cole ◽

Aaron J. Grocholski ◽

Doug Geisler ◽

Ata Sarajedini ◽

Verne V. Smith ◽

...

Keyword(s):

Star Formation ◽

Near Infrared ◽

Large Magellanic Cloud ◽

Star Formation History ◽

Red Giants ◽

Formation History ◽

History Of ◽

Red Giant ◽

Metallicity Distribution ◽

Modelling Process

AbstractWe have obtained metallicities from near-infrared calcium triplet spectroscopy for nearly a thousand red giants in 28 fields spanning a range of radial distances from the center of the bar to near the tidal radius. We have used these data to investigate the radius-metallicity and age-metallicity relations. A powerful application of these data is in conjunction with the analysis of deep HST color–magnitude diagrams (CMDs). Most of the power in determining a robust star-formation history from a CMD comes from the main-sequence turnoff and subgiant branches. The age-metallicity degeneracy that results is largely broken by the red giant branch color, but theoretical model RGB colors remain uncertain. By incorporating the observed metallicity distribution function into the modelling process, a star-formation history with massively increased precision and accuracy can be derived. We incorporate the observed metallicity distribution of the LMC bar into a maximum-likelihood analysis of the bar CMD, and present a new star formation history and age–metallicity relation for the bar. The bar is certainly younger than the disk as a whole, and the most reliable estimates of its age are in the 5–6 Gyr range, when the mean gas abundance of the LMC had already increased to [Fe/H] ≳ −0.6. There is no obvious metallicity gradient among the old stars in the LMC disk out to a distance of 8–10 kpc, but the bar is more metal-rich than the disk by ≈0.1–0.2 dex. This is likely to be the result of the bar's younger average age. In both disk and bar, 95% of the red giants are more metal-rich than [Fe/H] = −1.2.

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Star formation history of the solar neighbourhood as told by Gaia

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3576 ◽

2020 ◽

Vol 501 (1) ◽

pp. 302-328

Author(s):

Jairo A Alzate ◽

Gustavo Bruzual ◽

Daniel J Díaz-González

Keyword(s):

Star Formation ◽

Binary Stars ◽

Mass Function ◽

Initial Mass Function ◽

Star Formation History ◽

Solar Neighbourhood ◽

Data Set ◽

Formation History ◽

Solar Metallicity ◽

History Of

ABSTRACT The Gaia data release 2 (DR2) catalogue is the best source of stellar astrometric and photometric data available today. The history of the Milky Way galaxy is written in stone in this data set. Parallaxes and photometry tell us where the stars are today, when were they formed, and with what chemical content, that is, their star formation history (SFH). We develop a Bayesian hierarchical model suited to reconstruct the SFH of a resolved stellar population. We study the stars brighter than $G\, =\, 15$ within 100 pc of the Sun in Gaia DR2 and derive an SFH of the solar neighbourhood in agreement with previous determinations and improving upon them because we detect chemical enrichment. Our results show a maximum of star formation activity about 10 Gyr ago, producing large numbers of stars with slightly below solar metallicity (Z = 0.014), followed by a decrease in star formation up to a minimum level occurring around 8 Gyr ago. After a quiet period, star formation rises to a maximum at about 5 Gyr ago, forming stars of solar metallicity (Z = 0.017). Finally, star formation has been decreasing until the present, forming stars of Z = 0.03 at a residual level. We test the effects introduced in the inferred SFH by ignoring the presence of unresolved binary stars in the sample, reducing the apparent limiting magnitude, and modifying the stellar initial mass function.

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Main-Sequence Stars and the Star Formation History of the Outer Disk in the Large Magellanic Cloud

The Astrophysical Journal ◽

10.1086/177546 ◽

1996 ◽

Vol 466 ◽

pp. 732 ◽

Cited By ~ 36

Author(s):

J. S. Gallagher ◽

J. R. Mould ◽

E. de Feijter ◽

J. Holtzman ◽

B. Stappers ◽

...

Keyword(s):

Star Formation ◽

Main Sequence ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Star Formation History ◽

Main Sequence Stars ◽

Outer Disk ◽

Formation History ◽

History Of

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STAR FORMATION HISTORY OF A YOUNG SUPER-STAR CLUSTER IN NGC 4038/39: DIRECT DETECTION OF LOW-MASS PRE-MAIN SEQUENCE STARS

The Astrophysical Journal ◽

10.1088/0004-637x/710/2/1746 ◽

2010 ◽

Vol 710 (2) ◽

pp. 1746-1754 ◽

Cited By ~ 7

Author(s):

Julia Greissl ◽

Michael R. Meyer ◽

Micol H. Christopher ◽

Nick Z. Scoville

Keyword(s):

Star Formation ◽

Main Sequence ◽

Direct Detection ◽

Star Cluster ◽

Star Formation History ◽

Main Sequence Stars ◽

Formation History ◽

History Of ◽

Low Mass

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Spatial variations in the star formation history of the Large Magellanic Cloud

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308028585 ◽

2008 ◽

Vol 4 (S256) ◽

pp. 281-286

Author(s):

Carme Gallart ◽

Ingrid Meschin ◽

Antonio Aparicio ◽

Peter B. Stetson ◽

Sebastián L. Hidalgo

Keyword(s):

Star Formation ◽

Outer Part ◽

Large Magellanic Cloud ◽

Star Formation History ◽

Wide Field ◽

Galactocentric Distance ◽

Formation History ◽

The Galaxy ◽

History Of ◽

Star Formation Histories

AbstractBased on the quantitative analysis of a set of wide-field color—magnitude diagrams reaching the old main sequence-turnoffs, we present new LMC star-formation histories, and their variation with galactocentric distance. Some coherent features are found, together with systematic variations of the star-formation history among the three fields analyzed. We find two main episodes of star formation in all three fields, from 1 to 4 and 7 to 13 Gyr ago, with relatively low star formation around ≃ 4–7 Gyr ago. The youngest age in each field gradually increases with galactocentric radius; in the innermost field, LMC 0514–6503, an additional star formation event younger than 1 Gyr is detected, with star formation declining, however, in the last ≃ 200 Myr. The population is found to be older on average toward the outer part of the galaxy, although star formation in all fields seems to have started around 13 Gyr ago.

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The star formation history of the Fornax dwarf spheroidal galaxy

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310003200 ◽

2009 ◽

Vol 5 (S262) ◽

pp. 353-354

Author(s):

Enrico V. Held ◽

Eline Tolstoy ◽

Luca Rizzi ◽

Mary Cesetti ◽

Andrew A. Cole ◽

...

Keyword(s):

Star Formation ◽

Galaxy Evolution ◽

Stellar Population ◽

Main Sequence ◽

Dwarf Galaxy ◽

Star Formation History ◽

Stellar Content ◽

Formation History ◽

First Results ◽

History Of

AbstractWe present the first results of a comprehensive HST study of the star-formation history of Fornax dSph, based on WFPC2 imaging of 7 Fornax fields. Our observations reach the oldest main-sequence turnoffs, allowing us to address fundamental questions of dwarf galaxy evolution, such as the spatial variations in the stellar content, and whether the old stellar population is made up of stars formed in a very early burst or the result of a more continuous star formation.

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