scholarly journals The HST/ACS star formation history of the Tucana dwarf spheroidal galaxy: clues from the horizontal branch

2019 ◽  
Vol 630 ◽  
pp. A116 ◽  
Author(s):  
A. Savino ◽  
E. Tolstoy ◽  
M. Salaris ◽  
M. Monelli ◽  
T. J. L. de Boer
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Star Formation History ◽  
Horizontal Branch ◽  
Low Mass Stars ◽  
Formation History ◽  
History Of ◽  
Low Mass ◽  
Ancient Times ◽  
Red Giant

We report a new star formation history for the Tucana dwarf spheroidal galaxy, obtained from a new look at a deep HST/ACS colour-magnitude diagram. We combined information from the main sequence turn-off and the horizontal branch to resolve the ancient star formation rates on a finer temporal scale than previously possible. We show that Tucana experienced three major phases of star formation, two very close together at ancient times and the last one ending between 6 and 8 Gyr ago. We show that the three discrete clumps of stars on the horizontal branch are linked to the distinct episodes of star formation in Tucana. The spatial distribution of the clumps reveals that each generation of stars presents a higher concentration than the previous one. The simultaneous modelling of the horizontal branch and the main sequence turn-off also allows us to measure the amount of mass lost by red giant branch stars in Tucana with unprecedented precision, confirming dwarf spheroidals to be excellent laboratories to study the advanced evolution of low-mass stars.

scholarly journals The star formation history of the Fornax dwarf spheroidal galaxy

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.

scholarly journals Dwarf Galaxies: From the Epoch of Peak Star Formation to the Epoch of Reionization

2018 ◽  
Vol 14 (S344) ◽  
pp. 429-436
Author(s):  
Hakim Atek
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
High Redshift ◽  
Great Part ◽  
Star Formation History ◽  
Dark Matter Halos ◽  
Galaxy Surveys ◽  
Formation History ◽  
History Of ◽  
Low Mass

AbstractDwarf galaxies represent the dominant population at high redshift and they most likely contributed in great part to star formation history of the Universe and cosmic reionization. The importance of dwarf galaxies at high redshift has been mostly recognized in the last decade due to large progress in observing facilities allowing deep galaxy surveys to identify low-mass galaxies. This population appear to have extreme emission lines and ionizing properties that challenge stellar population models. Star formation follows a stochastic process in these galaxies, which has important implication on the ionizing photon production and its escape fraction whose measurements are challenging for both simulations and observations. Outstanding questions include: what are the physical properties at the origin of such extreme properties? What are the smallest dark matter halos that host star formation? Are dwarf galaxies responsible for cosmic reionization?

scholarly journals The star formation history of low-mass disk galaxies: A case study of NGC 300

2015 ◽  
Vol 585 ◽  
pp. A20 ◽  
Author(s):  
Xiaoyu Kang ◽  
Fenghui Zhang ◽  
Ruixiang Chang ◽  
Lang Wang ◽  
Liantao Cheng
Keyword(s):  
Star Formation ◽  
Star Formation History ◽  
Disk Galaxies ◽  
Formation History ◽  
History Of ◽  
Low Mass

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

2015 ◽  
Vol 12 (S316) ◽  
pp. 77-83
Author(s):  
Michele Cignoni ◽  
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Near Infrared ◽  
Mass Function ◽  
Large Magellanic Cloud ◽  
Initial Mass Function ◽  
Star Formation History ◽  
Formation History ◽  
History Of ◽  
30 Doradus

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.

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

2008 ◽  
Vol 4 (S256) ◽  
pp. 263-268 ◽  
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.

scholarly journals Low-mass young stellar population and star formation history of the cluster IC 1805 in the W4 H ii region

2017 ◽  
Vol 468 (3) ◽  
pp. 2684-2698 ◽  
Author(s):  
Neelam Panwar ◽  
M. R. Samal ◽  
A. K. Pandey ◽  
J. Jose ◽  
W. P. Chen ◽  
...  
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Star Formation History ◽  
Formation History ◽  
History Of ◽  
H Ii Region ◽  
Low Mass

scholarly journals Planets, evolved stars, and how they might influence each other.

2011 ◽  
Vol 7 (S283) ◽  
pp. 219-226 ◽  
Author(s):  
Eva Villaver
Keyword(s):  
White Dwarfs ◽  
Main Sequence ◽  
Planetary Nebulae ◽  
The Other ◽  
Horizontal Branch ◽  
Low Mass Stars ◽  
Evolved Stars ◽  
Low Mass ◽  
Red Giant

AbstractOver the last 20 years planetary searches have revealed a wealth of systems orbiting stars on the main sequence. Most of these low-mass stars eventually will evolve into the Giant phases before entering the planetary nebulae (PNe) stage. In the last years, the presence of planets has also been discovered around more massive evolved stars, mostly, along the Red Giant but also along the Horizontal Branch. Moreover, disks have been found around White Dwarfs presumably formed by tidally disrupted asteroids. In all, there is evidence that an evolved (ing) star might influence the survival of planets. In this review I will try to summarize such evidence but furthermore I will present the other side of the story, that is, how the presence of a planet might alter the evolution of stars and with that the PN formation.

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

1996 ◽  
Vol 466 ◽  
pp. 732 ◽  
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

scholarly journals The history of star formation in the Galactic young open cluster NGC 6231

2006 ◽  
Vol 2 (S237) ◽  
pp. 485-485
Author(s):  
Mario E. van den Ancker
Keyword(s):  
Star Formation ◽  
Open Cluster ◽  
Mass Function ◽  
Star Formation History ◽  
Wide Field ◽  
Star Formation Activity ◽  
Formation History ◽  
Young Open Cluster ◽  
History Of ◽  
Low Mass

AbstractWe study the star formation history of the galactic young open cluster NGC 6231 using new, deep, wide-field BVRI imaging. Contrary to previous suggestions, we do not find a lack of low-mass cluster members; our derived mass function is compatible with a Salpeter IMF. The star formation history of NGC 6231 appears to be bi-modal, with a first wave of star formation activity 3–5 Myr ago, followed by a new generation of stars forming ~ 1 Myr ago.

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