scholarly journals Star formation histories in dwarf irregular galaxies in the Local Group

1991 ◽  
Vol 148 ◽  
pp. 343-344
Author(s):  
L. Greggio ◽  
G. Marconi ◽  
P. Focardi ◽  
M. Tosi
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Mass Function ◽  
Initial Mass Function ◽  
Main Sequence Stars ◽  
Star Formation Activity ◽  
Irregular Galaxies ◽  
Ccd Observations ◽  
Star Formation Histories ◽  
Dwarf Irregular Galaxies

The process of star formation (SF) and the modalities with which it occurs in galaxies of different sizes are still poorly understood. On the other hand, interpretation of the chemical and photometric properties of galaxies requires the adoption of adequate laws for the SF rate and Initial Mass Function (IMF) in model computations. Dwarf irregular galaxies in the Local Group offer the chance to study their SF history through analysis of their HR diagrams, which can be derived down to V 25, corresponding to MV0, i.e. to main sequence stars of 2 M⊙. Therefore, for these galaxies, we can derive information on the star formation activity which has occurred over the last 1 Gyr approximately. In this framework, we have undertaken CCD observations of Dwarf irregular galaxies in the Local Group with ESO telescopes and briefly present here the results obtained for DDO 210, Sextans B and NGC 3109.

scholarly journals A new method to derive star formation histories in dwarf galaxies

2018 ◽  
Vol 14 (S344) ◽  
pp. 267-270
Author(s):  
Marius Čeponis ◽  
Rima Stonkutė ◽  
Vladas Vansevičius
Keyword(s):  
Star Formation ◽  
New Method ◽  
Star Forming ◽  
Stellar Photometry ◽  
Star Forming Regions ◽  
Density Maps ◽  
Irregular Galaxies ◽  
Star Formation Histories ◽  
Dwarf Irregular Galaxies ◽  
Inside Out

AbstractWe present a new method to derive 2D star formation histories in dwarf irregular galaxies. Based on multicolor stellar photometry data we have found that in the Leo A galaxy during the last ∽400 Myr star formation was propagating according to the inside-out scenario. Star-forming regions have spread strongly asymmetrically from the center and their present day distribution correlates well with the Hi surface density maps.

scholarly journals Chemical abundances of massive stars in Local Group galaxies

2003 ◽  
Vol 212 ◽  
pp. 30-37 ◽  
Author(s):  
Kim A. Venn ◽  
Andreas Kaufer ◽  
Eline Tolstoy ◽  
Rolf-Peter Kudritzki ◽  
Norbert Przybilla ◽  
...  
Keyword(s):  
High Efficiency ◽  
Local Group ◽  
Iron Group ◽  
Chemical Abundances ◽  
Elemental Abundances ◽  
Irregular Galaxies ◽  
Ngc 6822 ◽  
Process Elements ◽  
Star Formation Histories ◽  
Dwarf Irregular Galaxies

The relative abundances of elements in galaxies can provide valuable information on the stellar and chemical evolution of a galaxy. While nebulae can provide abundances for a variety of light elements, stars are the only way to directly determine the abundances of iron-group and s-process and r-process elements in a galaxy. The new 8m and 10m class telescopes and high-efficiency spectrographs now make high-quality spectral observations of bright supergiants possible in dwarf galaxies in the Local Group. We have been concentrating on elemental abundances in the metal-poor dwarf irregular galaxies, NGC 6822, WLM, Sextants A, and GR 8. Comparing abundance ratios to those predicted from their star formation histories, determined from color-magnitude diagrams, and comparing those ratios between these galaxies can give us new insights into the evolution of these dwarf irregular galaxies. Iron-group abundances also allow us to examine the metallicities of the stars in these galaxies directly, which affects their inferred mass loss rates and predicted stellar evolution properties.

Synergies between Massive Stars and Metal-poor Dwarf Irregular Galaxies

2018 ◽  
Vol 14 (S344) ◽  
pp. 178-181
Author(s):  
Miriam Garcia ◽  
Artemio Herrero ◽  
Francisco Najarro ◽  
Norberto Castro ◽  
Inés Camacho
Keyword(s):  
Massive Stars ◽  
Mass Function ◽  
Initial Mass Function ◽  
Star Formation History ◽  
Ob Stars ◽  
Irregular Galaxies ◽  
Formation History ◽  
Population Iii Stars ◽  
Dwarf Irregular Galaxies ◽  
Cosmic History

AbstractThe community of massive stars is working intensively on Local Group dwarf irregular galaxies (dIrr). They are a reservoir of metal-poor massive stars that serve to understand the physics of their higher redshift siblings and population III stars, interpret the farthest, most energetic SNe and GRBs, and compute feedback through Cosmic History. Along the way, we became interested in the recent star-formation history and initial mass-function of the host dIrr’s, their chemical evolution, and gas and dust content. Our team is working to unveil and characterize with spectroscopy the OB-stars in IC 1613, Sextans A and SagDIG, that form a sequence of decreasing metal content. We showcase some results to stimulate synergies between both communities.

scholarly journals A spatially-resolved study of initial mass function in the outer Galaxy

2016 ◽  
Vol 11 (S321) ◽  
pp. 34-36
Author(s):  
Chikako Yasui ◽  
Natsuko Izumi ◽  
Masao Saito ◽  
Naoto Kobayashi
Keyword(s):  
Mass Function ◽  
Initial Mass Function ◽  
Solar Neighborhood ◽  
High Mass ◽  
Initial Mass ◽  
Mass Detection ◽  
Spatially Resolved ◽  
Luminosity Functions ◽  
Irregular Galaxies ◽  
Dwarf Irregular Galaxies

AbstractOutskirts of spiral galaxies, including our own, and dwarf irregular galaxies are known to have a different environment from the solar neighborhood, e.g., low metallicities ( ~ − 1 dex). Among them, the outer Galaxy is the closest and hence is so far the only site suitable for population studies of resolved stars on the same basis as solar neighborhood. We have obtained NIR images of young clusters in the outer Galaxy, using the Subaru 8.2-m telescope, and clearly resolved cluster members with mass detection limits of ~ 0.1 M⊙. Based on the fitting of K-band luminosity functions (KLFs) for four clusters, we found that the initial mass function (IMF) in the outer Galaxy is consistent with that in the solar neighborhood in terms of the high-mass slope and IMF peak. Upcoming observations with a higher spatial resolution and sensitivity, using JWST, TMT, etc., will allow us to extend spatially-resolved studies of the IMF to Local Group galaxies.

scholarly journals The Recent Star Formation Histories of M81 Group Dwarf Irregular Galaxies

2008 ◽  
Vol 689 (1) ◽  
pp. 160-183 ◽  
Author(s):  
Daniel R. Weisz ◽  
Evan D. Skillman ◽  
John M. Cannon ◽  
Andrew E. Dolphin ◽  
Robert C. Kennicutt, Jr. ◽  
...  
Keyword(s):  
Star Formation ◽  
Irregular Galaxies ◽  
Star Formation Histories ◽  
Dwarf Irregular Galaxies

scholarly journals Stellar Populations of Dwarf Irregular Galaxies

1996 ◽  
Vol 171 ◽  
pp. 443-443
Author(s):  
R.E. Schulte-Ladbeck ◽  
Ulrich Hopp
Keyword(s):  
Star Formation ◽  
Stellar Populations ◽  
Ccd Photometry ◽  
Massive Galaxies ◽  
Star Formation Activity ◽  
Irregular Galaxies ◽  
Dwarf Irregular Galaxies

We recently completed two-color CCD photometry of resolved stars in 11 dwarf irregular galaxies (Hopp & Schulte-Ladbeck, 1995, A&AS 111, 527), selected because of their relative isolation from massive galaxies in the Kran-Korteweg – Tammann sample (1979, AN 300, 181). The B-R color magnitude diagrams (CMD) show that all galaxies studied had star formation activity in the last ∼ 108 yr. Several of them continue to form stars, the most active being UGC 5272 A (see Hopp & Schulte-Ladbeck, 1991, A&A 248, 1) while others, like DDO 210 (Hopp & Schulte-Ladbeck, 1994, ESO Conf. Workshop Proc. 49, 511), are pausing in their star formation activity. The CMDs enable us to select the brightest blue supergiants in these galaxies and to estimate their distances, D. Our values agree with the estimates based on the Virgo inflow model of Kran-Korteweg (1986, A&AS 66, 255) at the 30%-level. Prelimanary values are given in the table below.

Low‐Mass Star Formation and the Initial Mass Function in IC 348

1998 ◽  
Vol 508 (1) ◽  
pp. 347-369 ◽  
Author(s):  
K. L. Luhman ◽  
G. H. Rieke ◽  
C. J. Lada ◽  
E. A. Lada
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Mass Star ◽  
Low Mass
Sign in / Sign up

Export Citation Format

Share Document