scholarly journals The LBT satellites of Nearby Galaxies Survey (LBT-SONG): the satellite population of NGC 628

2020 ◽  
Vol 500 (3) ◽  
pp. 3854-3869
Author(s):  
A Bianca Davis ◽  
Anna M Nierenberg ◽  
Annika H G Peter ◽  
Christopher T Garling ◽  
Johnny P Greco ◽  
...  
Keyword(s):  
Milky Way ◽  
Large Magellanic Cloud ◽  
Satellite System ◽  
Mass Star ◽  
Star Forming ◽  
Local Volume ◽  
Satellite Galaxy ◽  
Measurement Methodology ◽  
Close Satellite ◽  
Nearby Galaxies

ABSTRACT We present the first satellite system of the Large Binocular Telescope Satellites Of Nearby Galaxies Survey (LBT-SONG), a survey to characterize the close satellite populations of Large Magellanic Cloud to Milky-Way-mass, star-forming galaxies in the Local Volume. In this paper, we describe our unresolved diffuse satellite finding and completeness measurement methodology and apply this framework to NGC 628, an isolated galaxy with ∼1/4 the stellar mass of the Milky Way. We present two new dwarf satellite galaxy candidates: NGC 628 dwA, and dwB with MV = −12.2 and −7.7, respectively. NGC 628 dwA is a classical dwarf while NGC 628 dwB is a low-luminosity galaxy that appears to have been quenched after reionization. Completeness corrections indicate that the presence of these two satellites is consistent with CDM predictions. The satellite colours indicate that the galaxies are neither actively star forming nor do they have the purely ancient stellar populations characteristic of ultrafaint dwarfs. Instead, and consistent with our previous work on the NGC 4214 system, they show signs of recent quenching, further indicating that environmental quenching can play a role in modifying satellite populations even for hosts smaller than the Milky Way.

scholarly journals First detection of [13C II] in the Large Magellanic Cloud

2019 ◽  
Vol 631 ◽  
pp. L12 ◽  
Author(s):  
Yoko Okada ◽  
Ronan Higgins ◽  
Volker Ossenkopf-Okada ◽  
Cristian Guevara ◽  
Jürgen Stutzki ◽  
...  
Keyword(s):  
Optical Depth ◽  
Line Profile ◽  
Large Magellanic Cloud ◽  
Abundance Ratio ◽  
Magellanic Cloud ◽  
Star Forming ◽  
Star Forming Regions ◽  
Distant Galaxies ◽  
Nearby Galaxies ◽  
Galactic Sources

Context. [13C II] observations in several Galactic sources show that the fine-structure [12C II] emission is often optically thick (the optical depths around 1 to a few). Aims. Our goal was to test whether this also affects the [12C II] emission from nearby galaxies like the Large Magellanic Cloud (LMC). Methods. We observed three star-forming regions in the LMC with upGREAT on board SOFIA at the frequency of the [C II] line. The 4 GHz bandwidth covers all three hyperfine lines of [13C II] simultaneously. For the analysis, we combined the [13C II] F = 1−0 and F = 1−1 hyperfine components as they do not overlap with the [12C II] line in velocity. Results. Three positions in N159 and N160 show an enhancement of [13C II] compared to the abundance-ratio-scaled [12C II] profile. This is likely due to the [12C II] line being optically thick, supported by the fact that the [13C II] line profile is narrower than [12C II], the enhancement varies with velocity, and the peak velocity of [13C II] matches the [O I] 63 μm self-absorption. The [12C II] line profile is broader than expected from a simple optical depth broadening of the [13C II] line, supporting the scenario of several PDR components in one beam having varying [12C II] optical depths. The derived [12C II] optical depth at three positions (beam size of 14″, corresponding to 3.4 pc) is 1−3, which is similar to values observed in several Galactic sources shown in previous studies. If this also applies to distant galaxies, the [C II] intensity will be underestimated by a factor of approximately 2.

scholarly journals High-Mass Star and Massive Cluster Formation in the Milky Way

2018 ◽  
Vol 56 (1) ◽  
pp. 41-82 ◽  
Author(s):  
Frédérique Motte ◽  
Sylvain Bontemps ◽  
Fabien Louvet
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Galactic Plane ◽  
Cluster Formation ◽  
Theoretical Models ◽  
High Mass ◽  
High Angular Resolution ◽  
Mass Star ◽  
Star Forming ◽  
Massive Cluster

This review examines the state-of-the-art knowledge of high-mass star and massive cluster formation, gained from ambitious observational surveys, which acknowledges the multiscale characteristics of these processes. After a brief overview of theoretical models and main open issues, we present observational searches for the evolutionary phases of high-mass star formation, first among high-luminosity sources and more recently among young massive protostars and the elusive high-mass prestellar cores. We then introduce the most likely evolutionary scenario for high-mass star formation, which emphasizes the link of high-mass star formation to massive cloud and cluster formation. Finally, we introduce the first attempts to search for variations of the star-formation activity and cluster formation in molecular cloud complexes in the most extreme star-forming sites and across the Milky Way. The combination of Galactic plane surveys and high–angular resolution images with submillimeter facilities such as Atacama Large Millimeter Array (ALMA) are prerequisites to make significant progress in the forthcoming decade.

scholarly journals The Sheet of Giants: Unusual properties of the Milky Way’s immediate neighbourhood

2020 ◽  
Vol 494 (2) ◽  
pp. 2600-2617 ◽  
Author(s):  
Maria K Neuzil ◽  
Philip Mansfield ◽  
Andrey V Kravtsov
Keyword(s):  
Milky Way ◽  
Number Density ◽  
Local Volume ◽  
Oblate Ellipsoid ◽  
Galaxy Distribution ◽  
Λcdm Model ◽  
The Galaxy ◽  
Nearby Galaxies ◽  
The Mean ◽  
The Impact

ABSTRACT We quantify the shape and overdensity of the galaxy distribution in the ‘Local Sheet’ within a sphere of R = 8 Mpc and compare these properties with the expectations of the ΛCDM model. We measure ellipsoidal axis ratios of c/a ≈ 0.16 and b/a ≈ 0.79, indicating that the distribution of galaxies in the Local Volume can be approximated by a flattened oblate ellipsoid, consistent with the ‘sheet’-like configuration noted in previous studies. In contrast with previous estimates that the Local Sheet has a density close to average, we find that the number density of faint and bright galaxies in the Local Volume is ≈1.7 and ≈5.2 times denser, respectively, than the mean number density of galaxies of the same luminosity. Comparison with simulations shows that the number density contrasts of bright and faint galaxies within 8 Mpc alone make the Local Volume a ≈2.5 σ outlier in the ΛCDM cosmology. Our results indicate that the cosmic neighbourhood of the Milky Way may be unusual for galaxies of similar luminosity. The impact of the peculiar properties of our neighbourhood on the properties of the Milky Way and other nearby galaxies is not yet understood and warrants further study.

scholarly journals TRIGONOMETRIC PARALLAXES OF HIGH MASS STAR FORMING REGIONS: THE STRUCTURE AND KINEMATICS OF THE MILKY WAY

2014 ◽  
Vol 783 (2) ◽  
pp. 130 ◽  
Author(s):  
M. J. Reid ◽  
K. M. Menten ◽  
A. Brunthaler ◽  
X. W. Zheng ◽  
T. M. Dame ◽  
...  
Keyword(s):  
Milky Way ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Trigonometric Parallaxes

The LMC vs. the Milky Way

2019 ◽  
Vol 14 (S353) ◽  
pp. 123-127 ◽  
Author(s):  
Gurtina Besla ◽  
Nicolás Garavito-Camargo
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Large Magellanic Cloud ◽  
Dark Matter Halo ◽  
Matter Distribution ◽  
Structure And Dynamics ◽  
Gravitational Perturbations ◽  
Satellite Galaxy ◽  
Stellar Halo ◽  
Dark Matter Distribution

AbstractRecent advancements in astrometry and in cosmological models of dark matter halo growth have significantly changed our understanding of the dynamics of the Local Group. The most dramatic changes owe to a new picture of the structure and dynamics of the Milky Way’s most massive satellite galaxy, the Large Magellanic Cloud (LMC), which is most likely on its first passage about the Milky Way and ten times larger in mass than previously assumed. The LMC’s orbit through the Milky Way’s dark matter and stellar halo will leave characteristic signatures in both density and kinematics. Furthermore, the gravitational perturbations produced by both direct tidal forcing from the LMC and the response of the halo to its passage will together cause significant perturbations to the orbits of tracers of the Milky Way’s dark matter distribution. We advocate for the use of basis field expansion methods to fully capture and quantify these effects.

scholarly journals The Distribution of Young Stars in Nearby Galaxies

1986 ◽  
Vol 116 ◽  
pp. 61-80 ◽  
Author(s):  
W. L. Freedman
Keyword(s):  
Spatial Distribution ◽  
Milky Way ◽  
Young Stars ◽  
Panoramic View ◽  
Star Forming ◽  
Individual Stars ◽  
Star Forming Regions ◽  
The Galaxy ◽  
External Galaxies ◽  
Nearby Galaxies

Although luminous stars are relatively rare, they can potentially be studied out to large distances. In our own Milky Way, this advantage is offset by obscuration due to dust in the plane of the Galaxy. In addition, distances to these individual stars are extremely difficult to determine. The study of external galaxies allows a panoramic view of the system and its individually brightest stars which are all at a common distance. The spatial distribution of star forming regions is immediately apparent, and the effects of obscuration are minimized. Nearby resolved galaxies therefore provide a rich resource for examining the properties of the intrinsically brightest stars and their relation to other components of the galaxy.

scholarly journals Trigonometric Parallaxes of High-mass Star-forming Regions: Our View of the Milky Way

2019 ◽  
Vol 885 (2) ◽  
pp. 131 ◽  
Author(s):  
M. J. Reid ◽  
K. M. Menten ◽  
A. Brunthaler ◽  
X. W. Zheng ◽  
T. M. Dame ◽  
...  
Keyword(s):  
Milky Way ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Trigonometric Parallaxes

scholarly journals Rotational parallaxes of nearby galaxies

2012 ◽  
Vol 8 (S289) ◽  
pp. 226-226
Author(s):  
Andreas Brunthaler
Keyword(s):  
High Mass ◽  
Mass Star ◽  
Proper Motions ◽  
Star Forming ◽  
Star Forming Regions ◽  
Long Baseline ◽  
First Results ◽  
Systematic Effects ◽  
Nearby Galaxies ◽  
Water Masers

AbstractAccurate geometric distances, which are inherently free of systematic effects are of very great importance for an independent recalibration of extragalactic distance estimators. Local Group galaxies are close enough for both primary and secondary distance indicators to be readily isolated in ground- and space-based observations. Astrometric accuracies of a few micro-arcseconds based on Very Long Baseline Interferometry (VLBI) observations of water masers in high-mass star-forming regions in nearby galaxies allow a measurement of the proper motions of these masers. Since these high-mass star-forming regions rotate with the galaxies, one can deduce a rotational parallax by comparing the known rotation curve with the proper motions of the masers. I provide an update of our previous rotation parallax of M33 and show first results of observations of the recently discovered water masers in the Andromeda galaxy (M31).

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