scholarly journals Characterisation of the Galactic thick disk

2013 ◽  
Vol 9 (S298) ◽  
pp. 17-27
Author(s):  
Thomas Bensby
Keyword(s):  
Galaxy Formation ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Thin Disk ◽  
Thick Disk ◽  
Host Galaxy ◽  
Galaxy Formation And Evolution ◽  
Formation History ◽  
History Of ◽  
Formation And Evolution

AbstractThick disks appear to be common in external large spiral galaxies and our own Milky Way also hosts one. The existence of a thick disk is possibly directly linked to the formation history of the host galaxy and if its properties is known it can constrain models of galaxy formation and help us to better understand galaxy formation and evolution. This brief review attempts to highlight some of the characteristics of the Galactic thick disk and how it relates to other stellar populations such as the thin disk and the Galactic bulge. Focus has been put on results from high-resolution spectroscopic data obtained during the last 10 to 15 years.

scholarly journals Assembling Spiral Galaxies

1996 ◽  
Vol 171 ◽  
pp. 11-18
Author(s):  
R.C. Kennicutt
Keyword(s):  
Galaxy Formation ◽  
Spiral Galaxies ◽  
Dynamical Evolution ◽  
Star Formation History ◽  
Physical Mechanisms ◽  
Hubble Sequence ◽  
Galaxy Formation And Evolution ◽  
The Galaxy ◽  
History Of ◽  
Formation And Evolution

Nearby spiral galaxies offer vital clues to some of the most fundamental questions about galaxy formation and evolution: What is the star formation history of the universe, past and future? When did disks form, during the final stages of a single primeval collapse, or as a continuous or episodic process? What is the evolutionary nature of the Hubble sequence, and what are the physical mechanisms that dictate the present-day Hubble type of a galaxy? Was Hubble type imprinted at birth, or can it be deterined or at least modified by infall, mergers, or secular dynamical evolution within the galaxy? These issues are not specific to spirals, of course, and much of this conference will address just these questions in a broader context. However present-day spirals offer unique advantages for studying these problems; they exhibit a broad range of dynamical and evolutionary properties, and the dynamical fragility of disks makes them excellent seismometers of galaxy interaction and merger rates at recent epochs.

scholarly journals The Stellar Population of the Thin Disk

2009 ◽  
Vol 5 (S265) ◽  
pp. 304-312
Author(s):  
Carlos Allende Prieto
Keyword(s):  
Galaxy Formation ◽  
Stellar Population ◽  
Milky Way ◽  
Galactic Disk ◽  
Symmetry Plane ◽  
Thin Disk ◽  
Solar Neighborhood ◽  
Galaxy Formation And Evolution ◽  
The Galaxy ◽  
Formation And Evolution

AbstractWe discuss recent observations of stars located close to the symmetry plane of the Milky Way, and examine them in the context of theories of Galaxy formation and evolution. The kinematics, ages, and compositions of thin disk stars in the solar neighborhood display complex patterns, and interesting correlations. The Galactic disk does not seem to pose any unsurmountable obstacles to hierarchical galaxy formation theories, but a model of the Milky Way able to reproduce the complexity found in the data will likely require a meticulous study of a significant fraction of the stars in the Galaxy. Making such an observational effort seems necessary in order to make a physics laboratory out of our own galaxy, and ultimately ensure that the most relevant processes are properly understood.

Comparing the star formation history of three nearby disk galaxies

2018 ◽  
Vol 14 (S344) ◽  
pp. 271-273
Author(s):  
Ruixiang Chang ◽  
Xiaoyu Kang ◽  
Fenghui Zhang
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Local Environment ◽  
Star Formation History ◽  
Disk Galaxies ◽  
Galaxy Formation And Evolution ◽  
Formation History ◽  
History Of ◽  
Formation And Evolution ◽  
Later Phase

AbstractUnderstanding the effect of environment on galaxy formation and evolution is one of the hot topics in extragalactic astronomy. Here we constructed a chemical evolution model of disk galaxies. By comparing the model predictions with the observed profiles, we investigated the star formation history of M33, NGC 300 and NGC 2403. We found that M33 has much longer infall timescale than NGC 300 and NGC 2403, and the star formation process of M33 is still active at later phase. Our results suggested that the cold gas supply of M33 is sufficient in the present-day, which may originate from the HI bridge between M33 and M31. In other words, we argue that the local environment plays an important role on the star formation history of a galaxy, at least for M33.

scholarly journals The star-formation history of the Milky Way Galaxy

2008 ◽  
Vol 4 (S258) ◽  
pp. 11-22 ◽  
Author(s):  
Rosemary F. G. Wyse
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Milky Way ◽  
Star Formation History ◽  
Milky Way Galaxy ◽  
Galaxy Formation And Evolution ◽  
History Of ◽  
Formation And Evolution ◽  
Star Formation Histories

AbstractThe star-formation histories of the main stellar components of the Milky Way constrain critical aspects of galaxy formation and evolution. I discuss recent determinations of such histories, together with their interpretation in terms of theories of disk galaxy evolution.

scholarly journals The Structure of the Stellar Hosts in Blue Compact Dwarf Galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 300-300
Author(s):  
R.O. Amorín ◽  
J.A.L. Aguerri ◽  
L.M. Cairós ◽  
N. Caon ◽  
C. Muñoz-Tuñón
Keyword(s):  
Galaxy Formation ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Structural Parameters ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Galaxy Formation And Evolution ◽  
Radial Profiles ◽  
Low Surface Brightness ◽  
Formation And Evolution

AbstractBlue compact dwarf (BCD) galaxies are gas-rich, low-luminosity (Mb≳-18 mag) and compact systems, currently undergoing violent star-formation burst (Sargent & Searle 1970). While it was initially hypothesized that they were very young galaxies (e.g. Sargent & Searle 1970, et al. 1988), the subsecuent detection of an extended, redder stellar host galaxy showed that the vast majority of them are old systems (e.g. Gil de Paz et al. 2003,2005). BCDs play an important role for understanding the process of galaxy formation and evolution.The structural properties of the low surface brightness stellar host in BCDs are often studied by fitting r1/n models to the outer regions of their radial profiles. The limitations imposed by the presence of a large starburst emission overlapping the underlying component makes this kind of analysis a difficult task.We propose a two-dimensional fitting methodology in order to improve the extraction of the structural parameters of the LSB host Amorín et al. 2006, submitted). A set of ideal simulations are presented in order to test the reliability of the method and to determine its robustness and flexibility. We present the different steps of the method discussing its advantages and weaknesses. We compare the results for a sample of eight objects with those already obtained using a one-dimensional technique (Caon et al. 2005).We fit a PSF convolved Sérsic model to the BVR images with the GALFIT publicly software (Peng et al. 2002). We restrict the fit to the stellar host by masking out the starburst region and take special care to minimize the sky-subtraction uncertainties. Consistency checks are performed to assess the reliability and accuracy of the derived structural parameters.We obtain robust fits for all the sample galaxies, all of which, except one, show low Sérsic indices n—very close to 1—with good agreement in the three bands. These findings suggest that the stellar hosts in BCDs have near-exponential profiles. Since the Sérsic index n of host galaxies is important in the context of the possible structural and evolutionary connections among the different types of dwarf galaxies, we are currently extending the study to a larger sample of objects. This kind of studies will help us to understand the mechanisms that form and shape BCD galaxies, and how they relate to the other dwarf galaxy classes.

scholarly journals Past, Present, and Future of the Scaling Relations of Galaxies and Active Galactic Nuclei

2021 ◽  
Vol 8 ◽  
Author(s):  
Mauro D’Onofrio ◽  
Paola Marziani ◽  
Cesare Chiosi
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Formation ◽  
Galactic Nuclei ◽  
Scaling Relations ◽  
Short History ◽  
Physical Mechanisms ◽  
Galaxy Formation And Evolution ◽  
The Galaxy ◽  
History Of ◽  
Formation And Evolution

We review the properties of the established Scaling Relations (SRs) of galaxies and active galactic nuclei (AGN), focusing on their origin and expected evolution back in time, providing a short history of the most important progresses obtained up to now and discussing the possible future studies. We also try to connect the observed SRs with the physical mechanisms behind them, examining to what extent current models reproduce the observational data. The emerging picture clarifies the complexity intrinsic to the galaxy formation and evolution process as well as the basic uncertainties still affecting our knowledge of the AGN phenomenon. At the same time, however, it suggests that the detailed analysis of the SRs can profitably contribute to our understanding of galaxies and AGN.

scholarly journals A Comparison of Chemical Evolution between the Milky Way and M31 Galaxy

2006 ◽  
Vol 2 (S235) ◽  
pp. 313-313
Author(s):  
J. Yin ◽  
J.L. Hou ◽  
R.X. Chang ◽  
S. Boissier ◽  
N. Prantzos
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Milky Way ◽  
Local Group ◽  
Spiral Galaxies ◽  
Star Formation History ◽  
Milky Way Galaxy ◽  
Andromeda Galaxy ◽  
Formation History ◽  
Formation And Evolution

Andromeda galaxy (M31,NGC224) is the biggest spiral in the Local Group. By studying the star formation history(SFH) and chemical evolution of M31, and comparing with the Milky Way Galaxy, we are able to understand more about the formation and evolution of spiral galaxies.

scholarly journals Stellar migrations and metal flows – Chemical evolution of the thin disc of a simulated Milky Way analogous galaxy

2020 ◽  
Vol 496 (1) ◽  
pp. 80-94 ◽  
Author(s):  
Fiorenzo Vincenzo ◽  
Chiaki Kobayashi
Keyword(s):  
Galaxy Formation ◽  
Milky Way ◽  
Formation Rate ◽  
Age Distribution ◽  
Radial Dependence ◽  
Radial Gradient ◽  
Thin Disc ◽  
Galaxy Formation And Evolution ◽  
Age Relation ◽  
Formation And Evolution

ABSTRACT In order to understand the roles of metal flows in galaxy formation and evolution, we analyse our self-consistent cosmological chemodynamical simulation of a Milky Way like galaxy during its thin-disc phase. Our simulated galaxy disc qualitatively reproduces the variation of the dichotomy in [α/Fe]–[Fe/H] at different Galactocentric distances as derived by APOGEE-DR16, as well as the stellar age distribution in [α/Fe]–[Fe/H] from APOKASC-2. The disc grows from the inside out, with a radial gradient in the star-formation rate during the entire phase. Despite the radial dependence, the outflow-to-infall ratio of metals in our simulated halo shows a time-independent profile scaling with the disc growth. The simulated disc undergoes two modes of gas inflow: (i) an infall of metal-poor and relatively low-[α/Fe] gas, and (ii) a radial flow where already chemically enriched gas moves inwards with an average velocity of ∼0.7 km s−1. Moreover, we find that stellar migrations mostly happen outwards, on typical time-scales of ∼5 Gyr. Our predicted radial metallicity gradients agree with the observations from APOGEE-DR16, and the main effect of stellar migrations is to flatten the radial metallicity profiles by 0.05 dex/kpc in the slopes. We also show that the effect of migrations can appear more important in [α/Fe] than in the [Fe/H]–age relation of thin-disc stars.

scholarly journals Globular Clusters as Probes of the Formation History of Elliptical Galaxies: Results for NGC 4472

2002 ◽  
Vol 207 ◽  
pp. 333-335
Author(s):  
K.L. Rhode ◽  
S.E. Zepf
Keyword(s):  
Galaxy Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Spiral Galaxies ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Cluster Systems ◽  
Large Sample ◽  
Formation History ◽  
History Of

We have undertaken a survey of the globular cluster systems of a large sample of elliptical and spiral galaxies in order to test predictions of elliptical galaxy formation models. Here we outline the survey and present a summary of our results for the Virgo elliptical NGC 4472.

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