The Star Formation History of the Local Group Dwarf Galaxy Leo I

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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Metallicity studies of the Galactic center: evidence for a top-heavy star formation history?

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314000696 ◽

2013 ◽

Vol 9 (S303) ◽

pp. 252-253

Author(s):

Francisco Najarro ◽

Diego de la Fuente ◽

Tom R. Geballe ◽

Don F. Figer

Keyword(s):

Star Formation ◽

Massive Star ◽

Local Group ◽

Galactic Center ◽

Massive Stars ◽

Star Formation History ◽

Test Bed ◽

Formation History ◽

History Of ◽

Stellar Properties

AbstractThe Galactic center (GC) region hosts three of the most massive resolved young clusters in the Local Group and constitutes a test bed for studying the star formation history of the region and inferring the possibility of a top-heavy scenario. Further, recent detection of a large number of apparently isolated massive stars within the inner 80 pc of the Galactic center has raised fundamental questions regarding massive star formation in a such a dense and harsh environment. Noting that most of the isolated massive stars have spectral analogs in the Quintuplet cluster, we have undertaken a combined analysis of the infrared spectra of both selected Quintuplet stars and the isolated objects using Gemini spectroscopy. We present preliminary results, aiming at α-elements versus iron abundances, stellar properties, ages and radial velocities which will differentiate the top-heavy and star-formation scenarios.

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The Star Formation History of the Carina Dwarf Galaxy

The Astronomical Journal ◽

10.1086/300326 ◽

1998 ◽

Vol 115 (5) ◽

pp. 1840-1855 ◽

Cited By ~ 100

Author(s):

Denise Hurley-Keller ◽

Mario Mateo ◽

James Nemec

Keyword(s):

Star Formation ◽

Dwarf Galaxy ◽

Star Formation History ◽

Formation History ◽

History Of

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Comparative Morphology of the HST Color-Magnitude Diagram of the Nearby Blue Compact Dwarf Galaxy VII Zw 403 with that of Local Group Dwarfs

Symposium - International Astronomical Union ◽

10.1017/s007418090020452x ◽

1999 ◽

Vol 192 ◽

pp. 464-468

Author(s):

R.E. Schulte-Ladbeck ◽

U. Hopp ◽

M. M. Crone

Keyword(s):

Star Formation ◽

Local Group ◽

Dwarf Galaxy ◽

Comparative Morphology ◽

Star Formation History ◽

Stellar Content ◽

Halo Structure ◽

Formation History ◽

Magnitude Diagram ◽

Blue Compact Dwarf Galaxy

There are no examples of Blue Compact Dwarf (BCD) galaxies known within the Local Group (LG). Multicolor HST/WFPC2 observations of the nearby BCD VII Zw 403 (= UGC 6456) now resolve single stars with the quality (in terms of limiting magnitude and completeness) previously achieved for LG dwarfs from the ground. We use the MI, V - I color-magnitude diagrams (CMDs) of several LG dwarfs as templates to assess the stellar content and star-formation history (SFH) of the BCD VII Zw 403. This is the first BCD for which a clear spatial segregation of the resolved stellar content into a “core-halo” structure is detected: active star formation is observed in the central region of VII Zw 403, while in “Baade's red sheet”, this young population is strikingly absent. If BCD halos are home to dominant ancient stellar populations, then the fossil record conflicts with delayed-format ion scenarios for dwarfs. We present a sketch of the SFH in the core and halo of VII Zw 403.

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Star formation at the edge of the Local Group: a rising star formation history in the isolated galaxy WLM

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2903 ◽

2019 ◽

Vol 490 (4) ◽

pp. 5538-5550 ◽

Cited By ~ 3

Author(s):

Saundra M Albers ◽

Daniel R Weisz ◽

Andrew A Cole ◽

Andrew E Dolphin ◽

Evan D Skillman ◽

...

Keyword(s):

Star Formation ◽

Local Group ◽

Dwarf Galaxies ◽

Dwarf Galaxy ◽

Hubble Space Telescope ◽

Optimal Path ◽

Stellar Mass ◽

Star Formation History ◽

Stellar Feedback ◽

Formation History

ABSTRACT We present the star formation history (SFH) of the isolated (D ∼ 970 kpc) Local Group dwarf galaxy Wolf–Lundmark–Melotte (WLM) measured from colour–magnitude diagrams (CMDs) constructed from deep Hubble Space Telescope imaging. Our observations include a central ($0.5 \, r_h$) and outer field ($0.7 \, r_h$) that reach below the oldest main-sequence turn-off. WLM has no early dominant episode of star formation: 20 per cent of its stellar mass formed by ∼12.5 Gyr ago ($z$ ∼ 5). It also has an SFR that rises to the present with 50 per cent of the stellar mass within the most recent 5 Gyr ($z$ < 0.7). There is evidence of a strong age gradient: the mean age of the outer field is 5 Gyr older than the inner field despite being only 0.4 kpc apart. Some models suggest such steep gradients are associated with strong stellar feedback and dark-matter core creation. The SFHs of real isolated dwarf galaxies and those from the Feedback in Realistic Environment suite are in good agreement for M⋆($z$ = 0) ∼ 107–109M⊙, but in worse agreement at lower masses ($M_{\star }(z=0) \sim 10^5\!-\!10^7 \, \mathrm{M}_{\odot }$). These differences may be explainable by systematics in the models (e.g. reionization model) and/or observations (HST field placement). We suggest that a coordinated effort to get deep CMDs between HST/JWST (crowded central fields) and WFIRST (wide-area halo coverage) is the optimal path for measuring global SFHs of isolated dwarf galaxies.

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