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The current rate of the expansion of space – called the Hubble constant – is a measure of the age and size of the universe. But recently, a new debate has emerged about the Hubble constant, potentiall...
How fast is the universe expanding? Galaxies provide one answer（图）
universe expanding Galaxies answer
2021/4/9
Determining how rapidly the universe is expanding is key to understanding our cosmic fate, but along with more precise data comes a conundrum. Estimates based on measurements in our current universe d...
The Origin of the Dust Arch in the Halo of NGC 4631: An Expanding Superbubble?
NGC 4631 galaxies
2014/12/24
We study the nature and the origin of the dust arch in the halo of the edge-on galaxy NGC 4631 detected by Neininger & Dumke. We present CO observations made using the new on-the-fly mapping mode with...
Boss quasars track the expanding universe: The most precise measurement yet
Boss quasars track expanding universe The most precise measurement yet
2014/4/16
The Baryon Oscillation Spectroscopic Survey (BOSS), the largest component of the third Sloan Digital Sky Survey (SDSS-III), pioneered the use of quasars to map density variations in intergalactic gas ...
Who discovered the expanding universe? Was it Hubble, or Lemaitre, or was it just the end result of a long series of investigations? In this article we summarise the main steps and contributions that ...
Abstract: The Hubble law, determined from the distance modulii and redshifts of galaxies, for the past 80 years, has been used as strong evidence for an expanding universe. This claim is reviewed in l...
Who discovered the expanding universe?
discover expanding universe Cosmology Extragalactic Astrophysics
2011/8/4
Abstract: Who discovered the expanding universe? Was it Hubble, or Lemaitre, or was it just the end result of a long series of investigations? In this article we summarise the main steps and contribut...
General conditions for scale-invariant perturbations in an expanding universe
General conditions scale-invariant perturbations expanding universe
2011/9/29
We investigate the general properties of expanding cosmological models which generate scale-invariant curvature perturbations in the presence of a variable speed of sound. We show that in an expanding...
Radiation-driven winds of hot luminous stars. XVI. Expanding atmospheres of massive and very massive stars and the evolution of dense stellar clusters
Radiation mechanisms: general – Methods: numerical – Radiative transfer – early Universe – Stars: early-type – mass- loss – stellar winds – very massive stars – stellar evolution
2011/9/27
Context: Starbursts, and particularly their high-mass stars, play an essential role in the evolution of galaxies. The winds of massive stars not only significantly influence their surroundings, but th...
Fermi coordinates, simultaneity, and expanding space in Robertson-Walker cosmologies
Fermi coordinates simultaneity
2011/1/13
Explicit Fermi coordinates are given for geodesic observers comoving with the Hubble flow in expanding Robertson-Walker spacetimes, along with exact expressions for the metric tensors in Fermi coordin...
Population I Wolf-Rayet Runaway Stars: the Case of WR124 and its Expanding Nebula M1-67
gamma-ray burst general stars distances stars individual individual
2010/11/10
In 1997 and 2008 we used the WFPC2 camera on board of the Hubble Space Telescope to obtain two sets of narrow-band H images of the runaway Wolf-Rayet (WR) star WR 124 surrounded by its nebula M1–67. ...
The Morphology of the Expanding Ejecta of V2491 Cygni (2008 N.2)
line profiles – stars novae – stars individual V2491 Cyg
2010/11/12
Determining the evolution of the ejecta morphology of novae provides valuable information
on the shaping mechanisms in operation at early stages of the nova outburst. Understanding
such mechanisms h...
During their infancy, stars are well known to expel matter violently in the form of well-defined,collimated outflows. A fairly unique exception is found in the Orion BN/KL star-forming region where a ...
W49A: A starburst triggered by expanding shells
massive star formation starburst giant molecular cloud UC Hii region molecular bubble
2010/11/11
Aims. W49A is a giant molecular cloud which harbors some of the most luminous embedded clusters in the Galaxy. However, the explanation for this starburst-like phenomenon is still under debate.
Propagation of the burst of radiation in expanding and recombining Universe: Thomson scattering
radiation expanding recombining Universe
2011/1/10
Within the framework of a flat cosmological model a propagation of an instantaneous burst of nonpolarized isotropic radiation is considered from the moment of its beginning at some initial redshift z0...