A New Theory of the Milky way

Easton, C.

doi:10.1086/140748

Cited by 19 publications

(11 citation statements)

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“…W. Morgan's first delineation of the spiral arms of our Galaxy using early‐type stars was a highlight of the 1951 meeting of the American Astronomical Society (Garrison 1995), and marked the culmination of a century of speculation about the nature of the Milky Way. Alexander (1852) appears to have been the first to argue that ‘the Milky Way and the stars within it together constitute a spiral with several (it may be four) branches, and a central (probably spheroidal) cluster.’ Decades later, Proctor (1869) and Easton (1900) also wrote about the Milky Way's spiral structure, with Easton (1900) suggesting the Sun was not at the center of the spiral pattern. [Correction made after online publication 20 Jul 2009: duplicate sentence removed.]…”

Section: Galactic Spiral Structurementioning

confidence: 99%

“…Alexander (1852) appears to have been the first to argue that "the Milky Way and the stars within it together constitute a spiral with several (it may be four) branches, and a central (probably spheroidal) cluster." Decades later Proctor (1869) and Easton (1900) also wrote about the Milky Way's spiral structure, although neither referenced Alexander's visionary treatise. In many works the Sun was assumed to lie at the centre of the spiral pattern, with Easton (1900) suggesting an alternative centre.…”

Section: Galactic Spiral Structurementioning

confidence: 99%

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Characteristics of the Galaxy according to Cepheids

Majaess

Turner

Lane

2009

Monthly Notices of the Royal Astronomical Society

118

121

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Classical and Type II Cepheids are used to reinvestigate specific properties of the Galaxy. A new Type II reddening-free Cepheid distance parameterization is formulated from LMC Cepheids (OGLE), with uncertainties typically no larger than 5-15%. A distance to the Galactic centre of R0=7.8+-0.6 kpc is derived from the median distance to Type II Cepheids in the bulge (OGLE), R0=7.7+-0.7 kpc from a distance to the near side of the bulge combined with an estimated bulge radius of 1.3+-0.3 kpc derived from planetary nebulae. The distance of the Sun from the Galactic plane inferred from classical Cepheid variables is Zsun=26+-3 pc, a result dependent on the sample's distance and direction because of the complicating effects of Gould's Belt and warping in the Galactic disk. Classical Cepheids and young open clusters delineate consistent and obvious spiral features, although their characteristics do not match conventional pictures of the Galaxy's spiral pattern. The Sagittarius-Carina arm is confirmed as a major spiral arm that appears to originate from a different Galactic region than suggested previously. Furthermore, a major feature is observed to emanate from Cygnus-Vulpecula and may continue locally near the Sun. Significant concerns related to the effects of metallicity on the VI-based reddening-free Cepheid distance relations used here are allayed by demonstrating that the computed distances to the Galactic centre, and to several globular clusters (M54, NGC 6441, M15, and M5) and galaxies (NGC 5128 and NGC 3198) which likely host Type II Cepheids: agree with literature results to within the uncertainties.Comment: Accepted for Publication (MNRAS

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Section: Galactic Spiral Structurementioning

confidence: 99%

Section: Galactic Spiral Structurementioning

confidence: 99%

Characteristics of the Galaxy according to Cepheids

Majaess

Turner

Lane

2009

Monthly Notices of the Royal Astronomical Society

118

121

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“…Wallace also rejected life on Mars. Despite occasional alternative suggestions (a particularly charming one has us at the center of a circular galactic disk, but spiral arms centered far away in Cygnus), 80 it took the 60" telescope on Mt. Wilson and half a decade of hard work by Harlow Shapley to pry us out of the galactic center.…”

Section: • 76 It Wasmentioning

confidence: 99%

Time Scales for Achieving Astronomical Consensus

Trimble

2008

Int. J. Mod. Phys. D

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The history of science can be recounted in many ways: by addressing the work of one person or school; by starting with the ancients and working chronologically up to the present; by focusing on a particular century; or by tracing a particular important idea as far back and forward as it can be found. The present discussion does none of these. Rather, it adopts the ordering of a standard introductory astronomy textbook, from t he solar system via stars and galaxies, to the universe as a whole, and in each regime picks out a few issues that were controversial or wrongly decided for a long time. For each, I attempt to identify a d uration of the period of uncertainty or error and some of the causes of the confusion. This is surely not an original idea, though I am not aware of having encountered it elsewhere, and it is not one that is likely to appeal to most 21st century historians of science, for whom the question "Who first got it right?" is not necessarily an important, or even appropriate, one. Some of the stories have been told as historical introductions to conferences and are here summarized and brought up to date. Others I had not previously addressed.

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“…Some remarkable reconstructions of the Milky Way as it might appear from outside appear in the first decades of the 20th century, Easton (1900) knew that we were supposed to be at the center of the whole system but were clearly not at the center of the distribution of bright star clusters and nebulae. His face-on galaxy has a system of spiral arms whose center has been pushed off to one side in the direction of Cygnus, while we reside in a sparser region at r 0 of a somewhat arbitrary circle.…”

Section: William Herschel and The Shape Of The Milky Waymentioning

confidence: 99%

Emergent Structure: the First Two Centuries of the First Two Eons

Trimble

2005

Symp. - Int. Astron. Union

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Scientific recognition of the existence, evolution, and significance of structure within the cosmos developed slowly. We follow the story here from the earliest times to the first systematic redshift surveys and the "Rubin-Ford effect," emphasizing the period beginning with William Herschel and ending about lunch time on Wednesday. The scientific issues cannot be put in any one linear order, because, for instance, some people were studying clusters of galaxies and measuring the mass of M31 while others still denied the existence of external galaxies.The merging of Greek philosophy with medieval church doctrine that was largely the work of Thomas Aquinas imposed this spherical symmetry on European thought after about 1260, along with immutability of the heavens, the four terrestrial elements + quintessence, and much else. Indeed many of the early readers of Copernicus were inclined to think that the most important thing he was saying was the primacy of uniform circular motion, whatever is at the center. But, before this, the 12th century universe of Hildegaard of Bingen had a spherical earth, but a pineapple-shaped lucidus ignis outside it. She also placed the fixed stars close to us, hail and lightening further out beyond the moon, followed by the sun and outer planets (as the stem of the pineapple). Thus she had not yet fully accepted immutability of the heavens as requiring hail, lightning, comets, meteors, and guest stars all to fall within the atmosphere. A Chinese model universe from about the same time is spherical and held up by dragons (Needham 1953). It also has an equatorial mount, rather than an ecliptic one like the European armillary spheres of the time, and the equatorial concept may well be a Chinese inventionThen the spheres and circles close in, first with earth at the center a la Ptolemy (and Martin Luther), then, increasingly, with the sun at the center, a la Copernicus.Next is the question of where to put the stars. Outside the orbit of Saturn, clearly, but how far outside, how many of them, and how far should they extend? Early on, these questions tended to get stirred in with old philosophical considerations of whether voids and infinities were conceivable and hence possible. For some people, they probably still do.Thomas Digges in 1576 extended his "orbe of starres fixed" to infinity (though not in the drawing) and allowed them to have planets and life. He said that the total assemblage though infinite was somehow vaguely spherical, but that it could have neither edges nor a center. Infinite, multiply inhabited, and more or less spherical universes are also to be found in the writings of Nicolas of Cusa (c. 1450), Giordano Bruno (before 1600!), and William Gilbert (d. 1602). Gilbert explicitly allowed the stars in his infinite distribution to be of intrinsically different size (meaning brightness).Kepler (d. 1630) considered the possibility of an infinite, fairly uniform distribution of stars, of which the sun would be merely an undistinguished one, but rejected both this and a "stoic" univ...

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A New Theory of the Milky way

Cited by 19 publications

References 0 publications

Characteristics of the Galaxy according to Cepheids

Characteristics of the Galaxy according to Cepheids

Time Scales for Achieving Astronomical Consensus

Emergent Structure: the First Two Centuries of the First Two Eons

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