scholarly journals Spatial variations in the Milky Way disc metallicity–age relation

2019 ◽  
Vol 489 (2) ◽  
pp. 1742-1752 ◽  
Author(s):  
Diane K Feuillet ◽  
Neige Frankel ◽  
Karin Lind ◽  
Peter M Frinchaboy ◽  
D A García-Hernández ◽  
...  
Keyword(s):  
Milky Way ◽  
Star Formation History ◽  
Chemical Abundance ◽  
Crucial Component ◽  
Stellar Ages ◽  
Formation History ◽  
History Of ◽  
Age Relation ◽  
Age Relations ◽  
Spatial Locations

ABSTRACT Stellar ages are a crucial component to studying the evolution of the Milky Way. Using Gaia DR2 distance estimates, it is now possible to estimate stellar ages for a larger volume of evolved stars through isochrone matching. This work presents [M/H]–age and [α/M]–age relations derived for different spatial locations in the Milky Way disc. These relations are derived by hierarchically modelling the star formation history of stars within a given chemical abundance bin. For the first time, we directly observe that significant variation is apparent in the [M/H]–age relation as a function of both Galactocentric radius and distance from the disc mid-plane. The [M/H]–age relations support claims that radial migration has a significant effect in the plane of the disc. Using the [M/H] bin with the youngest mean age at each radial zone in the plane of the disc, the present-day metallicity gradient is measured to be −0.059 ± 0.010 dex kpc−1, in agreement with Cepheids and young field stars. We find a vertically flared distribution of young stars in the outer disc, confirming predictions of models and previous observations. The mean age of the [M/H]–[α/M] distribution of the solar neighbourhood suggests that the high-[M/H] stars are not an evolutionary extension of the low-α sequence. Our observational results are important constraints to Galactic simulations and models of chemical evolution.

scholarly journals The growth of mass and metallicity in bulges and disks: CALIFA perspective

2012 ◽  
Vol 10 (H16) ◽  
pp. 338-338
Author(s):  
R. M. González Delgado ◽  
E. Pérez ◽  
R. Cid Fernandes ◽  
R. García-Benito ◽  
A. de Amorim ◽  
...  
Keyword(s):  
Spectral Synthesis ◽  
Morphological Type ◽  
Star Formation History ◽  
Stellar Ages ◽  
Formation History ◽  
History Of ◽  
Nearby Galaxies ◽  
First Time ◽  
Inside Out ◽  
Calar Alto

AbstractCALIFA (Calar Alto Legacy Integral Field Area) is a 3D spectroscopic survey of 600 nearby galaxies that we are obtaining with [email protected] at Calar Alto (Sánchez et al. 2012; Husemann et al. 2012). This pioneer survey is providing valuable clues on how the mass and metallicity grow in the different galactic spatial sub-components (“bulge” and “disk”). Processed through spectral synthesis techniques, CALIFA datacubes allow us to, for the first time, spatially resolve the star formation history of galaxies (Cid Fernandes et al. 2012). The richness of this approach is already evident from the results obtained for the first ~ 100 galaxies of the sample (Pérez et al. 2012). We have found that galaxies grow inside-out, and that the growth rate depends on a galaxy's mass. Here, we present the radial variations of physical properties sorting galaxies by their morphological type (Figure 1). We have found a good correlation between the stellar mass surface density, stellar ages and metallicities and the Hubble type, but being the the early type spirals (Sa-Sbc) the galaxies with strong negative age and metallicity gradient from the bulge to the disk.

The recurrent impact of the Sagittarius dwarf on the star formation history of the Milky Way

2020 ◽  
Vol 4 (10) ◽  
pp. 965-973 ◽  
Author(s):  
Tomás Ruiz-Lara ◽  
Carme Gallart ◽  
Edouard J. Bernard ◽  
Santi Cassisi
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Star Formation History ◽  
Formation History ◽  
History Of

scholarly journals On the recent star formation history of the Milky Way disk

New Astronomy ◽  
2004 ◽  
Vol 9 (6) ◽  
pp. 475-502 ◽  
Author(s):  
R. de la Fuente Marcos ◽  
C. de la Fuente Marcos
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Star Formation History ◽  
Formation History ◽  
History Of

scholarly journals Reconstructing the star formation history of the Milky Way disc(s) from chemical abundances

2015 ◽  
Vol 578 ◽  
pp. A87 ◽  
Author(s):  
O. Snaith ◽  
M. Haywood ◽  
P. Di Matteo ◽  
M. D. Lehnert ◽  
F. Combes ◽  
...  
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Star Formation History ◽  
Chemical Abundances ◽  
Formation History ◽  
History Of

scholarly journals The Milky Way’s nuclear star cluster: Old, metal-rich, and cuspy

2020 ◽  
Vol 641 ◽  
pp. A102 ◽  
Author(s):  
R. Schödel ◽  
F. Nogueras-Lara ◽  
E. Gallego-Cano ◽  
B. Shahzamanian ◽  
A. T. Gallego-Calvente ◽  
...  
Keyword(s):  
Black Hole ◽  
Star Formation ◽  
Milky Way ◽  
Star Cluster ◽  
Star Formation History ◽  
Central Black Hole ◽  
Formation History ◽  
History Of ◽  
Nuclear Cluster ◽  
Sgr A

Context. The environment of Sagittarius A* (Sgr A*), the central black hole of the Milky Way, is the only place in the Universe where we can currently study the interaction between a nuclear star cluster and a massive black hole and infer the properties of a nuclear cluster from observations of individual stars. Aims. This work aims to explore the star formation history of the nuclear cluster and the structure of the innermost stellar cusp around Sgr A*. Methods. We combined and analysed multi epoch high quality AO observations. For the region close to Sgr A* we apply the speckle holography technique to the AO data and obtain images that are ≥50% complete down to Ks ≈ 19 within a projected radius of 5″ around Sgr A*. We used H-band images to derive extinction maps. Results. We provide Ks photometry for roughly 39 000 stars and H-band photometry for ∼11 000 stars within a field of about 40″ × 40″, centred on Sgr A*. In addition, we provide Ks photometry of ∼3000 stars in a very deep central field of 10″ × 10″, centred on Sgr A*. We find that the Ks luminosity function (KLF) is rather homogeneous within the studied field and does not show any significant changes as a function of distance from the central black hole on scales of a few 0.1 pc. By fitting theoretical luminosity functions to the KLF, we derive the star formation history of the nuclear star cluster. We find that about 80% of the original star formation took place 10 Gyr ago or longer, followed by a largely quiescent phase that lasted for more than 5 Gyr. We clearly detect the presence of intermediate-age stars of about 3 Gyr in age. This event makes up about 15% of the originally formed stellar mass of the cluster. A few percent of the stellar mass formed in the past few 100 Myr. Our results appear to be inconsistent with a quasi-continuous star formation history. The mean metallicity of the stars is consistent with being slightly super solar. The stellar density increases exponentially towards Sgr A* at all magnitudes between Ks = 15−19. We also show that the precise properties of the stellar cusp around Sgr A* are hard to determine because the star formation history suggests that the star counts can be significantly contaminated, at all magnitudes, by stars that are too young to be dynamically relaxed. We find that the probability of observing any young (non-millisecond) pulsar in a tight orbit around Sgr A* and beamed towards Earth is very low. We argue that typical globular clusters, such as they are observed in and around the Milky Way today, have probably not contributed to the nuclear cluster’s mass in any significant way. The nuclear cluster may have formed following major merger events in the early history of the Milky Way.

scholarly journals The formation history of the Milky Way disc with high-resolution cosmological simulations

2021 ◽  
Vol 502 (2) ◽  
pp. 2251-2265
Author(s):  
Marco Giammaria ◽  
Alessandro Spagna ◽  
Mario G Lattanzi ◽  
Giuseppe Murante ◽  
Paola Re Fiorentin ◽  
...  
Keyword(s):  
High Resolution ◽  
Milky Way ◽  
Phase Particle ◽  
Stellar Mass ◽  
Star Formation History ◽  
Origin And Evolution ◽  
Formation History ◽  
Major Merger ◽  
History Of ◽  
Multi Phase

ABSTRACT We analyse from an observational perspective the formation history and kinematics of a Milky Way-like galaxy from a high-resolution zoom-in cosmological simulation that we compare to those of our Galaxy as seen by Gaia DR2 to better understand the origin and evolution of the Galactic thin and thick discs. The cosmological simulation was carried out with the gadget-3 TreePM+SPH code using the MUlti-Phase Particle Integrator (muppi) model. We disentangle the complex overlapping of stellar generations that rises from the top-down and inside-out formation of the galactic disc. We investigate cosmological signatures in the phase-space of mono-age populations and highlight features stemming from past and recent dynamical perturbations. In the simulation, we identify a satellite with a stellar mass of $1.2 \times 10^9~\rm {M}_\odot$, i.e. stellar mass ratio Δ ∼ 5.5 per cent at the time, accreted at z ∼ 1.6, which resembles the major merger Gaia–Sausage–Enceladus that produced the Galactic thick disc, i.e. Δ ∼ 6 per cent. We found at z ∼ 0.5–0.4 two merging satellites with a stellar mass of $8.8 \times 10^8~\rm {M}_\odot$ and $5.1 \times 10^8~\rm {M}_\odot$ that are associated to a strong starburst in the star formation history, which appears fairly similar to that recently found in the solar neighbourhood. Our findings highlight that detailed studies of coeval stellar populations kinematics, which are made available by current and future Gaia data releases and in synergy with simulations, are fundamental to unravel the formation and evolution of the Milky Way discs.

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