Interstellar absorption and an apparent anisotropy in the Hubble expansion

1975 ◽  
Vol 195 ◽  
pp. L7 ◽  
Author(s):  
F. D. A. Hartwick
Keyword(s):  
Interstellar Absorption ◽  
Hubble Expansion

Echelle Spectroscopy of Interstellar Absorption toward μ Columbae with the Goddard High Resolution Spectrograph

1999 ◽  
Vol 117 (1) ◽  
pp. 400-409 ◽  
Author(s):  
J. C. Brandt ◽  
S. R. Heap ◽  
E. A. Beaver ◽  
A. Boggess ◽  
K. G. Carpenter ◽  
...  
Keyword(s):  
High Resolution ◽  
Interstellar Absorption ◽  
Echelle Spectroscopy

Ultrafine Structure in the λ5797 Diffuse Interstellar Absorption Band

1998 ◽  
Vol 495 (2) ◽  
pp. 941-945 ◽  
Author(s):  
T. H. Kerr ◽  
R. E. Hibbins ◽  
S. J. Fossey ◽  
J. R. Miles ◽  
P. J. Sarre
Keyword(s):  
Absorption Band ◽  
Interstellar Absorption ◽  
Ultrafine Structure

Origin of the Diffuse Interstellar Absorption Bands

Nature ◽  
1968 ◽  
Vol 218 (5137) ◽  
pp. 153-153 ◽  
Author(s):  
W. W. DULEY
Keyword(s):  
Absorption Bands ◽  
Interstellar Absorption

scholarly journals 10. Radio observations of interstellar neutral hydrogen clouds

1957 ◽  
Vol 4 ◽  
pp. 66-66
Author(s):  
R. S. Lawrence
Keyword(s):  
Angular Resolution ◽  
Neutral Hydrogen ◽  
Optical Component ◽  
Absorption Lines ◽  
Radio Observations ◽  
Interstellar Absorption ◽  
Peak Intensity

The detailed relationship between optical interstellar absorption lines and 21-cm. observations is investigated in this paper.Dr Guido Münch, of the Mount Wilson and Palomar Observatories, provided the list of six intermediate-latitude stars shown in Table 1. The spectra of these stars all show complex absorption lines due to interstellar Ca 11. The 21-cm. line is measurable in four of the six regions, although the peak intensity is low in each case. It is noteworthy that for the first two stars on the list the radio velocity agrees closely with the velocity of an intense optical component. In view of the great difference in angular resolution, the failure to find correspondence in every case is not surprising.

scholarly journals Experimental Evidence in Support of the Possibility That the Local Space of Earth Is Confined

2019 ◽  
Vol 11 (4) ◽  
pp. 7
Author(s):  
Shlomo Barak ◽  
Arie Zigler ◽  
Jenya Papeer
Keyword(s):  
Experimental Evidence ◽  
Laser Pulses ◽  
Correlation Technique ◽  
Space Flights ◽  
Hubble Expansion ◽  
Global Space ◽  
Auto Correlation ◽  
Local Space ◽  
The Times ◽  
Synchronization Scheme

We have measured variations in the times of flight of 25fsec laser pulses, along a given distance from A to B, in different directions in space. Flights from A to B are termed one-way versus two-way - from A to B and back to A. The isotropy obtained, despite the motion of Earth in global space, supports the possibility that the local space of Earth, and probably that of other stars, is confined - captured inside the sphere of the star. To maintain space continuity, despite this confinement, space must necessarily be an elastic fluid, as Einstein, for a different reason, concluded in 1939. In addition, we wonder if this confinement of a local space in a star or galaxy explains its non-participation in the Hubble expansion of space. Our experiment used an auto-correlation technique that dispels the need for clocks, which in one-way measurements require a problematic synchronization scheme.

scholarly journals Do supernovae indicate an accelerating universe?

2021 ◽  
Author(s):  
Roya Mohayaee ◽  
Mohamed Rameez ◽  
Subir Sarkar
Keyword(s):  
Dark Energy ◽  
Large Scale ◽  
Bulk Flow ◽  
Expansion Rate ◽  
Accelerated Expansion ◽  
Accelerating Universe ◽  
Acoustic Oscillations ◽  
Independent Evidence ◽  
Peculiar Velocity ◽  
Hubble Expansion

AbstractIn the late 1990’s, observations of two directionally-skewed samples of, in total, 93 Type Ia supernovae were analysed in the framework of the Friedmann–Lemaître–Robertson–Walker (FLRW) cosmology. Assuming these to be ‘standard(isable) candles’ it was inferred that the Hubble expansion rate is accelerating as if driven by a positive Cosmological Constant $$\varLambda $$ Λ in Einstein’s theory of gravity. This is still the only direct evidence for the ‘dark energy’ that is the dominant component of today’s standard $$\varLambda $$ Λ CDM cosmological model. Other data such as baryon acoustic oscillations (BAO) in the large-scale distribution of galaxies, temperature fluctuations in the cosmic microwave background (CMB), measurement of stellar ages, the rate of growth of structure, etc are all ‘concordant’ with this model but do not provide independent evidence for accelerated expansion. The recent discussions about whether the inferred acceleration is real rests on analysis of a larger sample of 740 SNe Ia which shows that these are not quite standard candles, and more importantly highlights the ‘corrections’ that are applied to analyse the data in the FLRW framework. The latter holds in the reference frame in which the CMB is isotropic, whereas observations are carried out in our heliocentric frame in which the CMB has a large dipole anisotropy. This is assumed to be of kinematic origin i.e. due to our non-Hubble motion driven by local inhomogeneity in the matter distribution which has grown under gravity from primordial density perturbations traced by the CMB fluctuations. The $$\varLambda $$ Λ CDM model predicts how this peculiar velocity should fall off as the averaging scale is raised and the universe becomes sensibly homogeneous. However observations of the local ‘bulk flow’ are inconsistent with this expectation and convergence to the CMB frame is not seen. Moreover, the kinematic interpretation implies a corresponding dipole in the sky distribution of high redshift quasars, which is rejected by observations at $$4.9\sigma $$ 4.9 σ . Hence the peculiar velocity corrections employed in supernova cosmology are inconsistent and discontinuous within the data. The acceleration of the Hubble expansion rate is in fact anisotropic at $$3.9\sigma $$ 3.9 σ and aligned with the bulk flow. Thus dark energy could be an artefact of analysing data assuming that we are idealised observers in an FLRW universe, when in fact the real universe is inhomogeneous and anisotropic out to distances large enough to impact on cosmological analyses.

scholarly journals Quiescent and flaring lyman-α radiation of host stars and effects on exoplanets

2015 ◽  
Vol 11 (S320) ◽  
pp. 391-396
Author(s):  
Jeffrey L. Linsky ◽  
Kevin France ◽  
Yamila Miguel ◽  
Lisa Kaltenegger
Keyword(s):  
Emission Lines ◽  
Late Type ◽  
Chemical Abundances ◽  
Interstellar Absorption ◽  
Ultraviolet Spectra ◽  
M Stars ◽  
Host Stars ◽  
Stars Flare ◽  
Photochemical Models

AbstractLyman-α radiation dominates the ultraviolet spectra of G, K, and M stars and is a major photodissociation source for H2O, CO2, and CH4 in the upper atmospheres of exoplanets. We obtain intrinsic Lyman-α line fluxes for late-type stars by correcting for interstellar absorption or by scaling from other spectroscopic observables. When stars flare, all emission lines brighten by large factors as shown by HST spectra. We describe photochemical models of the atmosphere of the mini-Neptune GJ 436b (Miguel et al. 2015) that show the effects of flaring Lyman-α fluxes on atmospheric chemical abundances.

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