scholarly journals Extragalactic star-forming regions and open clusters in the Milky Way

2009 ◽  
Vol 5 (S266) ◽  
pp. 522-522
Author(s):  
F. Sakhibov ◽  
A. S. Gusev ◽  
N. V. Kharchenko ◽  
A. E. Piskunov
Keyword(s):  
Comparative Analysis ◽  
Milky Way ◽  
Interstellar Extinction ◽  
Young Star ◽  
Open Clusters ◽  
Evolutionary Sequence ◽  
Star Forming ◽  
Star Forming Regions ◽  
Irregular Galaxies

AbstractWe have carried out a comparative analysis of the evolution of integrated photometric parameters of young star-forming complexes in spiral and irregular galaxies and Galactic open clusters. We find that when the interstellar extinction is properly taken into account, the extragalactic complexes observed as giant Hii regions and open clusters in the Milky Way form a single evolutionary sequence of objects evolving at different stages.

scholarly journals Star Clusters in Irregular Galaxies in the Local Group

2002 ◽  
Vol 207 ◽  
pp. 94-104
Author(s):  
Eva K. Grebel
Keyword(s):  
Globular Clusters ◽  
Local Group ◽  
Cluster Formation ◽  
Star Clusters ◽  
Open Clusters ◽  
High Angular Resolution ◽  
Star Clusters And Associations ◽  
Star Forming ◽  
Star Forming Regions ◽  
Irregular Galaxies

I summarize our knowledge of star clusters and associations in irregular galaxies other than the Magellanic Clouds in the Local Group. Surveys affording complete area coverage at high angular resolution are still lacking. Confirmed globular clusters are known only in NGC 6822 and WLM. Very few dIrrs contain populous or sparse open clusters. There is a pronounced deficiency of intermediate-age and young clusters. Apart from parent galaxy mass, the lack of interactions may be a key reason for the lack of cluster formation in the dIrrs. All dIrrs have one or several short-lived OB associations in the star-forming regions in their centers.

scholarly journals Double trouble: Gaia reveals (proto)planetary systems that may experience more than one dense star-forming environment

2020 ◽  
Vol 501 (1) ◽  
pp. L12-L17
Author(s):  
Christina Schoettler ◽  
Richard J Parker
Keyword(s):  
Planetary Systems ◽  
Young Star ◽  
Young Stars ◽  
Orion Nebula ◽  
External Effects ◽  
Star Forming ◽  
Star Forming Regions ◽  
Ejection Process ◽  
Runaway Stars

ABSTRACT Planetary systems appear to form contemporaneously around young stars within young star-forming regions. Within these environments, the chances of survival, as well as the long-term evolution of these systems, are influenced by factors such as dynamical interactions with other stars and photoevaporation from massive stars. These interactions can also cause young stars to be ejected from their birth regions and become runaways. We present examples of such runaway stars in the vicinity of the Orion Nebula Cluster (ONC) found in Gaia DR2 data that have retained their discs during the ejection process. Once set on their path, these runaways usually do not encounter any other dense regions that could endanger the survival of their discs or young planetary systems. However, we show that it is possible for star–disc systems, presumably ejected from one dense star-forming region, to encounter a second dense region, in our case the ONC. While the interactions of the ejected star–disc systems in the second region are unlikely to be the same as in their birth region, a second encounter will increase the risk to the disc or planetary system from malign external effects.

scholarly journals X-Ray Coronae from Stars

1998 ◽  
Vol 188 ◽  
pp. 13-16
Author(s):  
R. Pallavicini
Keyword(s):  
Open Clusters ◽  
Temperature Structure ◽  
List Type ◽  
Star Forming ◽  
Spectroscopic Observations ◽  
Star Forming Regions ◽  
Complete Mapping ◽  
Sky Survey ◽  
Order Of Magnitude ◽  
Age Range

A number of major advances in stellar coronal physics have occurred since 1990 mainly as a consequence of imaging observations by ROSAT and spectroscopic observations by ASCA. These can be summarised as follows: 1.an all-sky survey has been performed by ROSAT at a sensitivity of ~ 2 × 10−13 erg cm−2 s−1, complemented by pointed observations an order of magnitude deeper;2.complete mapping and deeper pointings have been obtained for virtually all open clusters closer than ~ 500 pc, and covering the age range from ~ 30 Myr to ~ 700 Myr;3.complete mapping and deeper paintings have been obtained for several Star Forming Regions (SFRs) covering the age range ~ 1 to ~ 10 Myr;4.spectroscopic observations of bright coronal sources have been obtained with EUVE and ASCA allowing the derivation of the temperature structure and elemental abundances.

scholarly journals The Violent Interstellar Medium of Nearby Dwarf Galaxies

1999 ◽  
Vol 16 (1) ◽  
pp. 106-112 ◽  
Author(s):  
Fabian Walter
Keyword(s):  
Interstellar Medium ◽  
Gamma Ray ◽  
Dwarf Galaxies ◽  
Young Star ◽  
Stellar Winds ◽  
Star Forming ◽  
Star Forming Regions ◽  
Supernova Explosions ◽  
High Velocity Clouds ◽  
Ob Associations

AbstractHigh resolution HI observations of nearby dwarf galaxies (most of which are situated in the M81 group at a distance of about 3·2 Mpc) reveal that their neutral interstellar medium (ISM) is dominated by hole-like features most of which are expanding. A comparison of the physical properties of these holes with the ones found in more massive spiral galaxies (such as M31 and M33) shows that they tend to reach much larger sizes in dwarf galaxies. This can be understood in terms of the galaxy's gravitational potential. The origin of these features is still a matter of debate. In general, young star forming regions (OB-associations) are held responsible for their formation. This picture, however, is not without its critics and other mechanisms such as the infall of high velocity clouds, turbulent motions or even gamma ray bursters have been recently proposed. Here I will present one example of a supergiant shell in IC 2574 which corroborates the picture that OB associations are indeed creating these structures. This particular supergiant shell is currently the most promising case to study the effects of the combined effects of stellar winds and supernova explosions which shape the neutral interstellar medium of (dwarf) galaxies.

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 A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) – III. Exploring the properties of young associations through their variables, dippers, and candidate exoplanets

2020 ◽  
Vol 498 (4) ◽  
pp. 5972-5989
Author(s):  
D Nardiello
Keyword(s):  
Variable Stars ◽  
Open Clusters ◽  
Light Curves ◽  
Quality Data ◽  
Stellar Systems ◽  
Satellite Mission ◽  
Open Clusters And Associations ◽  
Star Forming ◽  
Star Forming Regions ◽  
Strong Candidate

ABSTRACT Young associations in star-forming regions are stellar systems that allow us to understand the mechanisms that characterize the stars in their early life and what happens around them. In particular, the analysis of the discs and of the exoplanets around young stars allows us to know the key processes that prevail in their evolution and understand the properties of the exoplanets orbiting older stars. The Transiting Exoplanet Survey Satellite mission is giving us the opportunity to extract and analyse the light curves of association members with high accuracy, but the crowding that affects these regions makes difficult the light curve extraction. In the PATHOS project, cutting-edge tools are used to extract high-precision light curves and identify variable stars and transiting exoplanets in open clusters and associations. In this work, I analysed the light curves of stars in five young (≲10 Myr) associations, searching for variables and candidate exoplanets. Using the rotational periods of the association members, I constrained the ages of the five stellar systems (∼2–10 Myr). I searched for dippers, and I investigated the properties of the dust that forms the circumstellar discs. Finally, I searched for transiting signals, finding six strong candidate exoplanets. No candidates with radius RP ≲ 0.9 RJ have been detected, in agreement with the expectations. The frequency of giant planets resulted to be ∼2–3 per cent, higher than that expected for field stars (≲ 1 per cent); the low statistic makes this conclusion not strong, and new investigations on young objects are mandatory to confirm this result.

scholarly journals Chemistry in the Envelopes around Massive Young Stars

2002 ◽  
Vol 12 ◽  
pp. 146-148
Author(s):  
Ewine F. van Dishoeck ◽  
Floris F.S. van der Tak
Keyword(s):  
Young Star ◽  
Young Stars ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Chemical Studies ◽  
H Ii Region ◽  
Infrared Wavelengths ◽  
Collapse Phase

AbstractRecent chemical studies of high-mass star-forming regions at submillimeter and infrared wavelengths reveal large variations in the abundances depending on evolutionary state. Such variations can be explained by freezing out of molecules onto grains in the cold collapse phase, followed by evaporation and high-temperature chemical reactions when the young star heats the envelope. Thus, the chemical composition can be a powerful diagnostic tool. A detailed study of a set of infrared-bright massive young stars reveals systematic increases in the gas/solid ratios and abundances of evaporated molecules with temperature. This ‘global heating’ plausibly results from the gradual dispersion of the envelopes. We argue that these objects form the earliest phase of massive star formation, before the ‘hot core’ and ultracompact H II region phase.

scholarly journals Galactic structure from trigonometric parallaxes of star-forming regions

2012 ◽  
Vol 8 (S289) ◽  
pp. 188-193 ◽  
Author(s):  
Mark J. Reid
Keyword(s):  
Interstellar Dust ◽  
Milky Way ◽  
Galactic Center ◽  
Star Forming ◽  
Fundamental Parameters ◽  
Star Forming Regions ◽  
Long Baseline ◽  
The Galaxy ◽  
Trigonometric Parallaxes ◽  
3D Information

AbstractRecently, astrometric accuracy approaching ~ 10 μas has become routinely possible with Very Long Baseline Interferometry. Since, unlike at optical wavelengths, interstellar dust is transparent at radio wavelengths, parallaxes and proper motions can now be measured for massive young stars (with maser emission) across the Galaxy, enabling direct measurements of the spiral structure of the Milky Way. Fitting the full 3D position and velocity vectors to a simple model of the Galaxy yields extremely accurate values for its fundamental parameters, including the distance to the Galactic Center, R0=8.38 ± 0.18 kpc, and circular rotation at the Solar Circle, Θ0 = 243 ± 7 km s−1. The rotation curve of the Milky Way, based for the first time on ‘gold standard’ distances and complete 3D information, appears to be very flat.

scholarly journals Mass segregation effects in very young open clusters

2007 ◽  
Vol 3 (S248) ◽  
pp. 481-483
Author(s):  
L. Chen ◽  
R. de Grijs ◽  
J. L. Zhao
Keyword(s):  
Star Formation ◽  
Strong Support ◽  
Open Clusters ◽  
Proper Motions ◽  
Star Forming ◽  
Star Forming Regions ◽  
Mass Segregation ◽  
The Way

AbstractWe derived proper motions and membership probabilities of stars in the regions of two very young (~ 2–4 Myr-old) open clusters NGC 2244 and NGC 6530. Both clusters show clear evidence of mass segregation, which provides strong support for the suggestion that the observed mass segregation is – at least partially – due to the way in which star formation has proceeded in these complex star-forming regions (“primordial” mass segregation).

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