On the Magellanic Stream, the Mass of the Galaxy and the Age of the Universe

1978 ◽  
pp. 123-132
Author(s):  
D. Lynden-Bell ◽  
William E. Kunkel ◽  
A. G. D. Philip ◽  
A. G. Davis
Keyword(s):  
The Galaxy ◽  
Age Of The Universe ◽  
Magellanic Stream ◽  
The Universe

scholarly journals On the Magellanic Stream, the Mass of the Galaxy and the Age of the Universe

1978 ◽  
Vol 79 ◽  
pp. 123-130
Author(s):  
D. Lynden-Bell
Keyword(s):  
Direct Determination ◽  
Large Mass ◽  
Circular Velocity ◽  
The Galaxy ◽  
Andromeda Nebula ◽  
Age Of The Universe ◽  
Magellanic Stream ◽  
Superluminal Expansion ◽  
The Universe

The Magellanic stream has been fitted with high accuracy in both position and velocity by the tidal tearing of a Magellanic Cloud. To get the good fit to the high velocity at the stream's tip at a suitable distance from the Galaxy we need either a large mass for the Galaxy, or a large circular velocity for the Sun, or both. An extragalactic method of determining the circular velocity yields the high value of Vc = 294 ± 42 km/sec and an orbit of poor accuracy for the relative motion of the Galaxy and the Andromeda nebula. Very large masses are needed if Andromeda and the Galaxy were formed together. A new direct determination of Hubble's constant from the “superluminal” expansion observed in VLB radio sources gives an age of the Universe of 9 billion years. Either larger masses still or smaller distances within the local group are necessary to bring Andromeda back towards us in so short a time.

Long-term astrophysical processes

2008 ◽  
Author(s):  
Fred C. Adams
Keyword(s):  
Background Radiation ◽  
Cosmological Parameters ◽  
Future Evolution ◽  
The Future ◽  
The Galaxy ◽  
Microwave Background Radiation ◽  
Type Ia ◽  
Long Time ◽  
Age Of The Universe ◽  
The Universe

As we take a longer-term view of our future, a host of astrophysical processes are waiting to unfold as the Earth, the Sun, the Galaxy, and the Universe grow increasingly older. The basic astronomical parameters that describe our universe have now been measured with compelling precision. Recent observations of the cosmic microwave background radiation show that the spatial geometry of our universe is flat (Spergel et al., 2003). Independent measurements of the red-shift versus distance relation using Type Ia supernovae indicate that the universe is accelerating and apparently contains a substantial component of dark vacuum energy (Garnavich et al., 1998; Perlmutter et al., 1999; Riess et al., 1998). This newly consolidated cosmological model represents an important milestone in our understanding of the cosmos. With the cosmological parameters relatively well known, the future evolution of our universe can now be predicted with some degree of confidence (Adams and Laughlin, 1997). Our best astronomical data imply that our universe will expand forever or at least live long enough for a diverse collection of astronomical events to play themselves out. Other chapters in this book have discussed some sources of cosmic intervention that can affect life on our planet, including asteroid and comet impacts (Chapter 11, this volume) and nearby supernova explosions with their accompanying gamma-rays (Chapter 12, this volume). In the longerterm future, the chances of these types of catastrophic events will increase. In addition, taking an even longer-term view, we find that even more fantastic events could happen in our cosmological future. This chapter outlines some of the astrophysical events that can affect life, on our planet and perhaps elsewhere, over extremely long time scales, including those that vastly exceed the current age of the universe. These projections are based on our current understanding of astronomy and the laws of physics, which offer a firm and developing framework for understanding the future of the physical universe (this topic is sometimes called Physical Eschatology – see the review of ćirković, 2003). Notice that as we delve deeper into the future, the uncertainties of our projections must necessarily grow.

DIFFUSION OF CHAOTIC ORBITS IN BARRED SPIRAL GALAXIES

2011 ◽  
Vol 21 (08) ◽  
pp. 2221-2233 ◽  
Author(s):  
M. HARSOULA ◽  
C. KALAPOTHARAKOS ◽  
G. CONTOPOULOS
Keyword(s):  
Spiral Structure ◽  
Initial Conditions ◽  
Unstable Periodic Orbits ◽  
Chaotic Orbits ◽  
The Galaxy ◽  
Barred Spiral Galaxy ◽  
Age Of The Universe ◽  
Barred Spiral Galaxies ◽  
The Universe ◽  
Asymptotic Manifolds

We study the diffusion of chaotic orbits in an N-body model simulating a barred spiral galaxy. Chaotic orbits with initial conditions outside corotation support the spiral structure of the galaxy due to the phenomenon of stickiness close and along the unstable asymptotic manifolds of the unstable periodic orbits. These orbits are diffused outwards after about 13 rotations of the bar. During this time, the spiral structure is clearly visible and then it fades out gradually. The diffusion time for the majority of the chaotic orbits with initial conditions inside corotation is much longer than the age of the Universe. These orbits support mainly the outer parts of the bar. However, a part of the chaotic orbits inside corotation are diffused outwards fast and support the spiral structure.

A New Way to Estimate the Age of the Universe

2014 ◽  
Vol 8 (6) ◽  
pp. 186
Author(s):  
Alilou Khalid ◽  
Az-Eddine L. Marrakchi
Keyword(s):  
Age Of The Universe ◽  
The Universe

The Long View of Planetary Systems

2018 ◽  
Author(s):  
Karel Schrijver
Keyword(s):  
Solar System ◽  
Milky Way ◽  
Planetary Systems ◽  
Giant Planets ◽  
Milky Way Galaxy ◽  
Population Statistics ◽  
The Past ◽  
General Terms ◽  
The Galaxy ◽  
The Universe

How many planetary systems formed before our’s did, and how many will form after? How old is the average exoplanet in the Galaxy? When did the earliest planets start forming? How different are the ages of terrestrial and giant planets? And, ultimately, what will the fate be of our Solar System, of the Milky Way Galaxy, and of the Universe around us? We cannot know the fate of individual exoplanets with great certainty, but based on population statistics this chapter sketches the past, present, and future of exoworlds and of our Earth in general terms.

scholarly journals Investigating the properties of a galaxy group at z = 0.6

2020 ◽  
Vol 15 (S359) ◽  
pp. 188-189
Author(s):  
Daniela Hiromi Okido ◽  
Cristina Furlanetto ◽  
Marina Trevisan ◽  
Mônica Tergolina
Keyword(s):  
Large Scale ◽  
The Other ◽  
Numerical Density ◽  
Spectroscopy Data ◽  
Stellar Kinematics ◽  
Galaxy Groups ◽  
The Galaxy ◽  
The Difference ◽  
The Impact ◽  
The Universe

AbstractGalaxy groups offer an important perspective on how the large-scale structure of the Universe has formed and evolved, being great laboratories to study the impact of the environment on the evolution of galaxies. We aim to investigate the properties of a galaxy group that is gravitationally lensing HELMS18, a submillimeter galaxy at z = 2.39. We obtained multi-object spectroscopy data using Gemini-GMOS to investigate the stellar kinematics of the central galaxies, determine its members and obtain the mass, radius and the numerical density profile of this group. Our final goal is to build a complete description of this galaxy group. In this work we present an analysis of its two central galaxies: one is an active galaxy with z = 0.59852 ± 0.00007, while the other is a passive galaxy with z = 0.6027 ± 0.0002. Furthermore, the difference between the redshifts obtained using emission and absorption lines indicates an outflow of gas with velocity v = 278.0 ± 34.3 km/s relative to the galaxy.

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