scholarly journals On the early evolution of Local Group dwarf galaxy types: star formation and supernova feedback

2018 ◽  
Vol 479 (2) ◽  
pp. 1514-1527 ◽  
Author(s):  
José R Bermejo-Climent ◽  
Giuseppina Battaglia ◽  
Carme Gallart ◽  
Arianna Di Cintio ◽  
Chris B Brook ◽  
...  
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxy ◽  
Early Evolution ◽  
Supernova Feedback

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

1999 ◽  
Vol 118 (5) ◽  
pp. 2245-2261 ◽  
Author(s):  
Carme Gallart ◽  
Wendy L. Freedman ◽  
Antonio Aparicio ◽  
Giampaolo Bertelli ◽  
Cesare Chiosi
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxy ◽  
Star Formation History ◽  
Formation History ◽  
History Of

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

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.

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

2019 ◽  
Vol 490 (4) ◽  
pp. 5538-5550 ◽  
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.

scholarly journals Hierarchical clustering in the Local Group dwarf galaxy NGC 6822

2009 ◽  
Vol 5 (S266) ◽  
pp. 538-538
Author(s):  
S. Schmeja ◽  
D. A. Gouliermis ◽  
R. S. Klessen ◽  
W. J. G. de Blok ◽  
F. Walter
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Minimum Spanning Tree ◽  
Dwarf Galaxy ◽  
Nearest Neighbour ◽  
Giant Molecular Clouds ◽  
Star Forming ◽  
Star Forming Regions ◽  
Ngc 6822 ◽  
Hierarchy Of Structures

AbstractStar formation appears to be clumped into a hierarchy of structures, from giant molecular clouds down to individual cores and clusters, which are often hierarchical themselves, showing significant substructure. This has been demonstrated for our Galaxy through the application of sophisticated statistical methods, in particular the nearest-neighbour density and the minimum spanning tree (MST), to different star-forming regions. Here we present our analysis of clustered star formation as demonstrated through the detection of structures of young stellar populations in the dwarf star-forming galaxy NGC 6822.

scholarly journals The Local Group Dwarf Galaxies. The Star Formation Histories derived using the Long Period Variable Stars

2018 ◽  
Vol 14 (S344) ◽  
pp. 125-129
Author(s):  
Elham Saremi ◽  
Atefeh Javadi ◽  
Jacco Th. van Loon ◽  
Habib Khosroshahi ◽  
Sara Rezaei kh ◽  
...  
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Stellar Populations ◽  
Variable Stars ◽  
Star Formation History ◽  
Long Period ◽  
Period Variable ◽  
Monitoring Survey

AbstractDwarf galaxies in the Local Group (LG) represent a distinct as well as diverse family of tracers of the earliest phases of galaxy assembly and the processing resulting from galactic harrassment. Their stellar populations can be resolved and used as probes of the evolution of their host galaxy. In this regard, we present the first reconstruction of the star formation history (SFH) of them using the most evolved AGB stars that are long period variable (LPV). LPV stars trace stellar populations as young as ∼ 30 Myr to as old as the oldest globular clusters. For the nearby, relatively massive and interacting gas-rich dwarf galaxies, the Magellanic Clouds, we found that the bulk of the stars formed ∼ 10 Gyr ago for the LMC, while the strongest episode of star formation in the SMC occurred a few Gyr later. A peak in star formation around 0.7 Gyr ago in both Clouds is likely linked to their recent interaction. The Andromeda satellite pair NGC147/185 show different histories; the main epoch of star formation for NGC 185 occurred 8.3 Gyr ago, followed by a much lower, but relatively constant star formation rate (SFR). In the case of NGC 147, the SFR peaked only 6.9 Gyr ago, staying intense until ∼ 3 Gyr ago. Star formation in the isolated gas-rich dwarf galaxy IC 1613 has proceeded at a steady rate over the past 5 Gyr, without any particular dominant epoch. Due to lack of sufficient data, we have conducted an optical monitoring survey at the Isaac Newton Telescope (INT) of 55 dwarf galaxies in the LG to reconstruct the SFH of them uniformly. The observations are made over ten epochs, spaced approximately three months apart, as the luminosity of LPV stars varies on timescales of months to years. The system of galactic satellites of the large Andromeda spiral galaxy (M31) forms one of the key targets of our monitoring survey. We present the first results in the And I dwarf galaxy, where we discovered 116 LPVs among over 10,000 stars.

scholarly journals Feedback from supermassive and intermediate-mass black holes at galaxy centers using cosmological hydrodynamical simulations

2019 ◽  
Vol 15 (S356) ◽  
pp. 184-188
Author(s):  
Paramita Barai
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Dwarf Galaxy ◽  
Galactic Nuclei ◽  
Intermediate Mass ◽  
Chemical Enrichment ◽  
Multi Wavelength ◽  
Wavelength Emission ◽  
Hydrodynamical Simulations ◽  
Supernova Feedback

AbstractAccretion of matter onto central Black Holes (BHs) in galaxies liberates enormous amounts of feedback energy, which affects the environment from pc to Mpc scales. These BHs are usually Supermassive BHs (SMBHs: mass ⩾106M⊙) existing at the centers of active galactic nuclei (AGN), which are widely observed through their multi-wavelength emission at all cosmic epochs. Relatively recently, Intermediate-Mass BHs (IMBHs: mass = 100−106M⊙) have started to be observed hosted in Dwarf Galaxy (DG) centers. Some of the central IMBHs in DGs show signatures of activity in the form of low-luminosity AGN. We have performed Cosmological Hydrodynamical Simulations to probe SMBHs in high-z quasars (Barai et al. 2018), and IMBHs in DGs (Barai & de Gouveia Dal Pino 2019). Our simulations employ the 3D TreePM SPH code GADGET-3, and include metal cooling, star formation, chemical enrichment, stellar evolution, supernova feedback, AGN accretion and feedback. Analyzing the simulation output in post-processing, we investigate the growth of the first IMBHs and the first SMBHs, as well as their impact on star-formation.

The Stellar Content of the Local Group Dwarf Galaxy Phoenix

1999 ◽  
Vol 118 (2) ◽  
pp. 862-882 ◽  
Author(s):  
D. Martínez-Delgado ◽  
C. Gallart ◽  
A. Aparicio
Keyword(s):  
Local Group ◽  
Dwarf Galaxy ◽  
Stellar Content
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