scholarly journals Predicting the Water Content of Interstellar Objects from Galactic Star Formation Histories

2021 ◽  
Vol 924 (1) ◽  
pp. L1
Author(s):  
Chris Lintott ◽  
Michele T. Bannister ◽  
J. Ted Mackereth
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Protoplanetary Disks ◽  
Bimodal Distribution ◽  
Formation Processes ◽  
Water Fraction ◽  
Low Metallicity ◽  
Water Fractions ◽  
Star Formation Histories ◽  
High Metallicity

Abstract Planetesimals inevitably bear the signatures of their natal environment, preserving in their composition a record of the metallicity of their system’s original gas and dust, albeit one altered by the formation processes. When planetesimals are dispersed from their system of origin, this record is carried with them. As each star is likely to contribute at least 1012 interstellar objects (ISOs), the Galaxy’s drifting population of ISOs provides an overview of the properties of its stellar population through time. Using the EAGLE cosmological simulations and models of protoplanetary formation, our modeling predicts an ISO population with a bimodal distribution in their water mass fraction: objects formed in low-metallicity, typically older, systems have a higher water fraction than their counterparts formed in high-metallicity protoplanetary disks, and these water-rich objects comprise the majority of the population. Both detected ISOs seem to belong to the lower water fraction population; these results suggest they come from recently formed systems. We show that the population of ISOs in galaxies with different star formation histories will have different proportions of objects with high and low water fractions. This work suggests that it is possible that the upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time will detect a large enough population of ISOs to place useful constraints on models of protoplanetary disks, as well as galactic structure and evolution.

scholarly journals A VLT/MUSE analysis of HeIIλ1640 emitters at z = 2 – 4

2019 ◽  
Vol 15 (S352) ◽  
pp. 78-78
Author(s):  
Themiya Nanayakkara
Keyword(s):  
Star Formation ◽  
Binary Stars ◽  
Stellar Population ◽  
Population Models ◽  
X Ray ◽  
Uv Emission ◽  
Low Metallicity ◽  
Star Formation Histories ◽  
X Ray Binaries ◽  
The Universe

AbstractIn the quest to study early star-formation physics in the universe, one of the most sought after tracers is HeIIλ1640, with its presence in the lack of other metal emission/absorption lines generally being interpreted as evidence for metal-poor stellar populations. HeII ionizing photons are produced via sources of hard ionizing radiation and requires photons with energies ⩾ 54.4eV, however, traditional stellar population models lack sufficient ionising photons to match with current observations. Our analysis of z = 2 – 4 HeIIλ1640 emitters from deep 10-30h pointings from MUSE has shown that ISM properties inferred from multiple rest-UV diagnostics are not compatible with requirements necessary to reproduce HeIIλ1640 equivalent-widths. Thus, we have used latest generation of single, rotational, and binary stellar population models with realistic dust physics to explore rest-UV emission line diagnostics and link with H and He+ ionisation photon production efficiencies (ξion (H,He+)) in a variety of stellar/gas metallicities and star-formation histories. I will discus our latest results and show that including ‘exotic’ stellar phenomena such as extreme low-metallicity binary stars, X-ray binaries, and dust dissociation physics may be necessary to lessen the tension between models and observations.

Infrared Studies of the Young Stellar Population of 30 Doradus

1980 ◽  
Vol 4 (1) ◽  
pp. 90-92
Author(s):  
P. J. McGregor ◽  
A. R. Hyland
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Cluster Formation ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Formation Processes ◽  
Excellent Opportunity ◽  
Infrared Studies ◽  
30 Doradus

The 30 Doradus region offers an excellent opportunity to study cluster formation processes and recent star formation in the Large Magellanic Cloud.

scholarly journals Substructure in Dwarf Galaxies

2004 ◽  
Vol 21 (4) ◽  
pp. 379-381
Author(s):  
Matthew Coleman
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Large Scale ◽  
Stellar Population ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Tidal Interaction ◽  
Kinematic Evolution ◽  
Dark Material ◽  
Star Formation Histories

AbstractRecent years have seen a series of large-scale photometric surveys with the aim of detecting substructure in nearby dwarf galaxies. Some of these objects display a varying distribution of each stellar population, reflecting their star formation histories. Also, dwarf galaxies are dominated by dark matter, therefore luminous substructure may represent a perturbation in the underlying dark material. Substructure can also be the effect of tidal interaction, such as the disruption of the Sagittarius dSph by the Milky Way. Therefore, substructure in dwarf galaxies manifests the stellar, structural, and kinematic evolution of these objects.

scholarly journals Spatially resolved properties of galaxies with a kinematically distinct core

2021 ◽  
Vol 647 ◽  
pp. A181
Author(s):  
Kiyoaki Christopher Omori ◽  
Tsutomu T. Takeuchi
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Stellar Population ◽  
Main Body ◽  
Stellar Kinematics ◽  
Stellar Core ◽  
Spatially Resolved ◽  
Star Formation Histories ◽  
Inside Out ◽  
Detailed Picture

Aims. Interacting galaxies show unique irregularities in their kinematic structures. By investigating the spatially resolved kinematics and stellar population properties of galaxies that demonstrate irregularities, we can paint a detailed picture of the formation and evolutionary processes that took place during their lifetimes. Methods. In this work, we focused on galaxies with a specific kinematic irregularity: a kinematically distinct stellar core (KDC). In particular, we considered counter-rotating galaxies in which the core and main body of are rotating in opposite directions. We visually identified 11 MaNGA galaxies with a KDC from their stellar kinematics, and we investigated their spatially resolved stellar and gaseous kinematic properties, namely the two-dimensional stellar and gaseous velocity and velocity-dispersion (σ) maps. Additionally, we examined the stellar population properties, as well as spatially resolved recent star formation histories, using the Dn4000 and Hδ gradients. Results. The galaxies display multiple off-centred symmetrical peaks in the stellar σ maps. The gaseous velocity and σ maps display regular properties. The stellar population properties and their respective gradients show differing properties depending on the results of the spatially resolved emission line diagnostics of the galaxies, with some but not all galaxies showing inside-out quenching. The star formation histories also largely differ based on the spatially resolved emission line diagnostics, but most galaxies show indications of recent star formation either in their outskirts or core. Conclusions. We find a distinct difference in kinematic and stellar population properties in galaxies with a counter-rotating stellar core, which depends on its classification using spatially resolved emission line diagnostics.

scholarly journals The properties of He IIλ1640 emitters at z ∼  2.5–5 from the VANDELS survey

2020 ◽  
Vol 636 ◽  
pp. A47 ◽  
Author(s):  
A. Saxena ◽  
L. Pentericci ◽  
M. Mirabelli ◽  
D. Schaerer ◽  
R. Schneider ◽  
...  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Stellar Population ◽  
Stellar Ages ◽  
Significant Difference ◽  
Consistent Manner ◽  
Multi Wavelength ◽  
Low Metallicity ◽  
Stellar Masses ◽  
X Ray Binaries

Aims. Strong He II emission is produced by low-metallicity stellar populations. Here, we aim to identify and study a sample of He IIλ1640-emitting galaxies at redshifts of z ∼ 2.5 − 5 in the deep VANDELS spectroscopic survey. Methods. We identified a total of 33 Bright He II emitters (S/N >  2.5) and 17 Faint emitters (S/N <  2.5) in the VANDELS survey and used the available deep multi-wavelength data to study their physical properties. After identifying seven potential AGNs in our sample and discarding them from further analysis, we divided the sample of Bright emitters into 20 Narrow (FWHM <  1000 km s−1) and 6 Broad (FWHM >  1000 km s−1) He II emitters. We created stacks of Faint, Narrow, and Broad emitters and measured other rest-frame UV lines such as O III] and C III] in both individual galaxies and stacks. We then compared the UV line ratios with the output of stellar population-synthesis models to study the ionising properties of He II emitters. Results. We do not see a significant difference between the stellar masses, star-formation rates, and rest-frame UV magnitudes of galaxies with He II and no He II emission. The stellar population models reproduce the observed UV line ratios from metals in a consistent manner, however they under-predict the total number of He II ionising photons, confirming earlier studies and suggesting that additional mechanisms capable of producing He II are needed, such as X-ray binaries or stripped stars. The models favour subsolar metallicities (∼0.1 Z⊙) and young stellar ages (106 − 107 years) for the He II emitters. However, the metallicity measured for He II emitters is comparable to that of non-He II emitters at similar redshifts. We argue that galaxies with He II emission may have undergone a recent star-formation event, or may be powered by additional sources of He II ionisation.

scholarly journals Stellar populations of HII galaxies

2018 ◽  
Vol 615 ◽  
pp. A55 ◽  
Author(s):  
Eduardo Telles ◽  
Jorge Melnick
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Spectral Energy Distribution ◽  
Age Determination ◽  
Stellar Mass ◽  
Star Formation History ◽  
Spectral Energy ◽  
Model Parameters ◽  
Formation History ◽  
Star Formation Histories

Aims. We present a UV to mid-IR spectral energy distribution (SED) study of a large sample of SDSS DR13 HII galaxies. These galaxies are selected as starbursts (EW(Hα) > 50Å) and for their high-excitation locus in the upper left region of the BPT diagram. Their photometry was derived from the cross-matched GALEX, SDSS, UKDISS, and WISE catalogs. Methods. We used CIGALE modeling and a SED fitting routine with the parametrization of a three-burst star formation history, and a comprehensive analysis of all other model parameters. We were able to estimate the contribution of the underlying old stellar population to the observed equivalent width of Hβ, and allow for more accurate burst age determination. Results. We found that the star formation histories of HII Galaxies can be reproduced remarkably well by three major eras of star formation. In addition, the SED fitting results indicate that in all cases the current burst produces a small percent of the total stellar mass, i.e., the bulk of stellar mass in HII galaxies has been produced by the past episodes of star formation, and also indicate that at a given age the Hβ luminosity depends only on the mass of young stars favoring a universal IMF for massive stars. Most importantly, the current star formation episodes are maximum starbursts that produce stars at the highest possible rate.

scholarly journals UV upturn versus UV weak galaxies: differences and similarities of their stellar populations unveiled by a de-biased sample

2020 ◽  
Vol 500 (2) ◽  
pp. 1870-1883
Author(s):  
M L L Dantas ◽  
P R T Coelho ◽  
P Sánchez-Blázquez
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Principal Component ◽  
Stellar Populations ◽  
Spectral Energy ◽  
Two Samples ◽  
Star Formation Histories ◽  
Uv Upturn

ABSTRACT The ultraviolet (UV) upturn is characterized by an unexpected up-rise of the UV flux in quiescent galaxies between the Lyman limit and 2500 Å. By making use of colour–colour diagrams, one can subdivide UV bright red-sequence galaxies in two groups: UV weak and upturn. With these two groups, we propose a comparison between their stellar population properties with the goal of establishing differences and similarities between them. We make use of propensity score matching to mitigate potential biases between the two samples, by selecting similar objects in terms of redshift and stellar mass. Also, we take advantage of spectral energy distribution (SED) fitting results from magphys made available by the GAMA collaboration. The analyses are made by comparing the distributions from the SED fitting directly, as well as investigating the differences in correlations between their parameters, and finally by using principal component analysis. We explore important differences and similarities between UV weak and upturn galaxies in terms of several parameters, such as: metallicity, age, specific star formation rate, time of last burst of star-formation, to mention a few. Notable differences are those concerning (g − r) colour, metallicity, and time since last burst of star-formation: UV upturn are redder in the optical, more metallic, and their last burst of star-formation happened earlier in time. These differences suggest that UV upturn systems have shorter star-formation histories (i.e. have been evolving more passively) when compared to UV weak galaxies. Consequently, these last seem to have a higher diversity of stellar populations.

scholarly journals Disentangling Nitrogen and Carbon Abundances in Early-Type Galaxies

2009 ◽  
Vol 5 (S262) ◽  
pp. 438-439
Author(s):  
Elisa Toloba ◽  
Patricia Sánchez-Blázquez ◽  
Javier Gorgas ◽  
Brad K. Gibson
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Velocity Dispersion ◽  
Population Models ◽  
Early Type ◽  
Carbon And Nitrogen ◽  
Wide Range ◽  
Style Indices ◽  
Star Formation Histories

AbstractThe near-UV NH3360 feature has been measured in a sample of 35 early-type galaxies in a wide range of masses and environments. We found that, contrary to what is seen with Mg- and C-sensitive Lick-style indices, NH3360 does not vary significantly with galaxy velocity dispersion. When compared with solar-scaled stellar population models N/Fe appears mildly enhanced. We do not detect any difference in the NH3360 index between galaxies in different environments. We outline the important implications of these conclusions for our understanding of the origin of carbon and nitrogen, and the star formation histories of early-type galaxies.

scholarly journals Dwarf ellipticals in the eye of SAURON: dynamical & stellar population analysis in 3D

2014 ◽  
Vol 10 (S309) ◽  
pp. 161-162
Author(s):  
Agnieszka Ryś ◽  
Jesús Falcón-Barroso ◽  
Glenn van de Ven ◽  
Mina Koleva
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Population Analysis ◽  
Secondary Star ◽  
La Palma ◽  
Angular Momenta ◽  
Star Formation Activity ◽  
Order Of Magnitude ◽  
Dwarf Elliptical Galaxies ◽  
Star Formation Histories

AbstractWe present the dynamical and stellar population analysis of 12 dwarf elliptical galaxies (dEs) observed using the SAURON IFU (WHT, La Palma). We demonstrate that dEs have lower angular momenta than their presumed late-type progenitors and we show that dE circular velocity curves are steeper than the rotation curves of galaxies with equal and up to an order of magnitude higher luminosity. Transformation due to tidal harassment is able to explain all of the above, unless the dE progenitors were already compact and had lower angular momenta at higher redshifts. We then look at the star formation histories (SFHs) of our galaxies and find that for the majority of them star formation activity was either still strong at a few Gyr of age or they experienced a secondary burst of star formation roughly at that time. This latter possibility would be in agreement with the scenario where tidal harassment drives the remaining gas inwards and induces a secondary star formation episode. Finally, one of our galaxies appears to be composed exclusively of an old population (≳12 Gyr). Combining this with our earlier dynamical results, we conclude that it either was ram-pressure stripped early on in its evolution in a group environment and subsequently tidally heated (which lowered its angular momentum and increased compactness), or that it evolved in situ in the cluster's central parts, compact enough to avoid tidal disruption.

scholarly journals Stellar formation in Brightest Cluster Galaxies

2009 ◽  
Vol 5 (S262) ◽  
pp. 450-451
Author(s):  
Tatiana Zapata Pichinao ◽  
Gastão B. Lima Neto
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
External Source ◽  
Star Formation History ◽  
Dynamic State ◽  
X Ray ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
First Results ◽  
Low Metallicity

AbstractWe study the interplay between stellar population of the Brightest Cluster Galaxies (BCG) and cluster global properties. We use X-ray properties from Chandra, ROSAT and ASCA observations and BCGs spectra from SDSS-DR6. Using STARLIGHT we determined the star formation history of the BCGs and look for relations with the intra-cluster gas properties. Our first results show no correlation between the recent star formation with x-ray temperature and dynamic state. An important star formation is happening in cool-core Cluster. This new stellar population has low metallicity, pointing to an external source of cold gas to form stars.

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