50 Years of Brown Dwarfs

50 Years of Brown Dwarfs PDF

Author: Viki Joergens

Publisher: Springer Science & Business Media

Published: 2013-11-27

Total Pages: 174

ISBN-13: 3319011626

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The years 2012/2013 mark the 50th anniversary of the theoretical prediction that Brown Dwarfs, i.e. degenerate objects which are just not massive enough to sustain stable hydrogen fusion, exist. Some 20 years after their discovery, how Brown Dwarfs form is still one of the main open questions in the theory of star formation. In this volume, the pioneers of Brown Dwarf research review the history of the theoretical prediction and the subsequent discovery of Brown Dwarfs. After an introduction, written by Viki Joergens, reviewing Shiv Kumar's theoretical prediction of the existence of brown dwarfs, Takenori Nakano reviews his and Hayashi's calculation of the Hydrogen Burning Minimum Mass. Both predictions happened in the early 1960s. Jill Tarter then writes on the introduction of the term 'Brown Dwarf', before Ben Oppenheimer, Rafael Rebolo and Gibor Basri describe their first discovery of Brown Dwarfs in the 1990s. Lastly, Michael Cushing and Isabelle Baraffe describe the development of the field to the current state of the art. While the book is mainly aimed at the Brown Dwarf research community, the description of the pioneering period in a scientific field will attract general readers interested in astronomy as well.

Very Low-Mass Stars and Brown Dwarfs

Very Low-Mass Stars and Brown Dwarfs PDF

Author: Rafael Rebolo

Publisher: Cambridge University Press

Published: 2000-11-27

Total Pages: 284

ISBN-13: 9780521663359

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This volume provides a state-of-the-art review of our current knowledge of brown dwarfs and very low-mass stars. The hunt for and study of these elusive objects is currently one of the most dynamic areas of research in astronomy for two reasons. Brown dwarfs bridge the gap between stars and planets, and they may constitute an important part of the 'dark matter' of the Universe. This volume presents review articles from a team of international authorities who gathered at a conference in La Palma to assess the spectacular progress that has been made in this field in the last few years.

The Initial Mass Function 50 Years Later

The Initial Mass Function 50 Years Later PDF

Author: Edvige Corbelli

Publisher: Springer Science & Business Media

Published: 2007-10-06

Total Pages: 551

ISBN-13: 1402034075

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Theideatocelebrate50yearsoftheSalpeterIMFoccurredduringtherecent IAU General Assembly in Sydney, Australia. Indeed, it was from Australia that in July 1954 Ed Salpeter submitted his famous paper "The Luminosity Function and Stellar Evolution" with the rst derivation of the empirical stellar IMF. This contribution was to become one of the most famous astrophysics papers of the last 50 years. Here, Ed Salpeter introduced the terms "original mass function" and "original luminosity function", and estimated the pro- bility for the creation of stars of given mass at a particular time, now known as the "Salpeter Initial Mass Function", or IMF. The paper was written at the Australian National University in Canberra on leave of absence from Cornell University (USA) and was published in 1955 as 7 page note in the Astroph- ical Journal Vol. 121, page 161. To celabrate the 50th anniversary of the IMF, along with Ed Salpeter’s 80th birthday, we have organized a special meeting that brought together scientists involved in the empirical determination of this fundamental quantity in a va- ety of astrophysical contexts and other scientists fascinated by the deep imp- cations of the IMF on star formation theories, on the physical conditions of the gas before and after star formation, and on galactic evolution and cosmology. The meeting took place in one of the most beautiful spots of the Tuscan countryside, far from the noise and haste of everyday life.

New Light on Dark Stars

New Light on Dark Stars PDF

Author: Neill I. Reid

Publisher: Springer Science & Business Media

Published: 2013-11-27

Total Pages: 492

ISBN-13: 1447136632

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Perhaps the most common question that a child asks when he or she sees the night sky from a dark site for the first time is: 'How many stars are there?' This happens to be a question which has exercised the intellectual skills of many astronomers over the course of most of the last century, including, for the last two decades, one of the authors of this text. Until recently, the most accurate answer was 'We are not certain, but there is a good chance that almost all of them are M dwarfs. ' Within the last three years, results from new sky-surveys - particularly the first deep surveys at near infrared wavelengths - have provided a breakthrough in this subject, solidifying our census of the lowest-mass stars and identifying large numbers of the hitherto almost mythical substellar-mass brown dwarfs. These extremely low-luminosity objects are the central subjects of this book, and the subtitle should be interpreted accordingly. The expression 'low-mass stars' carries a wide range of meanings in the astronomical literature, but is most frequently taken to refer to objects with masses comparable with that of the Sun - F and G dwarfs, and their red giant descendants. While this definition is eminently reasonable for the average extragalactic astronomer, our discussion centres on M dwarfs, with masses of no more than 60% that of the Sun, and extends to 'failed stars' - objects with insufficient mass to ignite central hydrogen fusion.

The Scientific American Book of the Cosmos

The Scientific American Book of the Cosmos PDF

Author: David Levy

Publisher: St. Martin's Press

Published: 2014-07-22

Total Pages: 656

ISBN-13: 1466876131

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Finally, the entire body of our scientific knowledge of the universe is available in one definitive volume. Scientific American, the oldest and most popular science magazine in the world, has prepared the most comprehensive and comprehensible book on the subject ever. Under the direction of renowned astronomer David H. Levy, this spectacular book assembles the best minds in science to give clear and accessible explanations of the nature of the cosmos. Newly commissioned essays by working scientists at the top of their fields and classic writings by such luminaries as Albert Einstein, Francis Crick, and Carl Sagan take us to the frontiers of space and time-from sub-atomic particles to the edge of the universe. Both thoughtful and provocative, this book asks-and answers-the big questions, such as: o How did our solar system evolve? o What forces lie at the center of the atom? o What is the size of the universe? o What is dark matter? o What is the possibility of extraterrestrial life? o What is the importance of superstrings? o How do galaxies form? Dazzling full-color and black-and-white photographs aid in articulating the latest theories about the size, age, nature, and expansion of the universe, and make this book a delight to behold. Essays are grouped by topic, from the largest phenomena, such as the formation of the universe, down to the smallest detail, such as the makeup of an atom. In addition, each section contains an illuminating introduction by David Levy that binds the essays together and creates a whole picture. The Scientific American Book of the Cosmos is a valuable addition to the bookshelf of both professional astronomers and science enthusiasts alike.

Brown Dwarf Companions to Young Solar an

Brown Dwarf Companions to Young Solar an PDF

Author: Stanimir Metchev

Publisher: Universal-Publishers

Published: 2006-02

Total Pages: 256

ISBN-13: 158112290X

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We present results from an adaptive optics survey conducted with the Palomar and Keck telescopes over 3 years, which measured the frequency of stellar and sub-stellar companions to Sun-like stars. The survey sample contains 266 stars in the 3-10000 million year age range at heliocentric distances between 8 and 200 parsecs and with spectral types between F5-K5. A sub-sample of 101 stars, between 3-500 million years old, were observed in deep exposures with a coronagraph to search for faint sub-stellar companions. A total of 288 candidate companions were discovered around the sample stars, which were re-imaged at subsequent epochs to determine physical association with the candidate host stars by checking for common proper motion. Benefitting from a highly accurate astrometric calibration of the observations, we were able to successfully apply the common proper motion test in the majority of the cases, including stars with proper motions as small as 20 milli-arcseconds/year. The results from the survey include the discovery of three new brown dwarf companions (HD 49197B, HD 203030B, and ScoPMS 214B), 43 new stellar binaries, and a triple system. The physical association of an additional, a priori-suspected, candidate sub-stellar companion to the star HII 1348 is astrometrically confirmed. The newly-discovered and confirmed young brown dwarf companions span a range of spectral types between M5 and T0.5, and will be of prime significance for constraining evolutionary models of young brown dwarfs and extra-solar planets. Based on the 3 new detections of sub-stellar companions in the 101 star sub-sample and following a careful estimate of the survey incompleteness, a Bayesian statistical analysis shows that the frequency of 0.012-0.072 solar-mass brown dwarfs in 30-1600 AU orbits around young solar analogs is 6.8% (-4.9%, +8.3%; 2-sigma limits). While this is a factor of 3 lower than the frequency of stellar companions to G-dwarfs in the same orbital range, it is significantly higher than the frequency of brown dwarfs in 0-3 AU orbits discovered through precision radial velocity surveys. It is also fully consistent with the observed frequency of 0-3 AU extra-solar planets. Thus, the result demonstrates that the radial-velocity "brown dwarf desert" does not extend to wide separations, contrary to previous belief.

The Lost Planets

The Lost Planets PDF

Author: John Wenz

Publisher: MIT Press

Published: 2019-10-08

Total Pages: 201

ISBN-13: 0262354624

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A fascinating account of the pioneering astronomer who claimed (erroneously) to have discovered a planet outside the solar system. There are innumerable planets revolving around innumerable stars across our galaxy. Between 2009 and 2018, NASA's Kepler space telescope discovered thousands of them. But exoplanets—planets outside the solar system—appeared in science fiction before they appeared in telescopes. Astronomers in the early decades of the twentieth century spent entire careers searching for planets in other stellar systems. In The Lost Planets, John Wenz offers an account of the pioneering astronomer Peter van de Kamp, who was one of the first to claim discovery of exoplanets. Van de Kamp, working at Swarthmore College's observatory, announced in 1963 that he had identified a planet around Barnard's Star, the second-closest star system to the Sun. He cited the deviations in Barnard's star's path—“wobbles” that suggested a large object was lurching around the star. Van de Kamp became something of a celebrity (appearing on a television show with “Mr. Wizard,” Don Henry), but subsequent research did not support his claims. Wenz describes van de Kamp's stubborn refusal to accept that he was wrong, discusses the evidence found by other researchers, and explains recent advances in exoplanet detection, including transit, radial velocity, direct imaging, and microlensing. Van de Kamp retired from Swarthmore in 1972, and died in 1995 at 93. In 2009, Swarthmore named its new observatory the Peter van de Kamp Observatory. In the 1990s, astronomers discovered and confirmed the first planet outside our solar system. In 2018, an exoplanet was detected around Barnard's Star—not, however, the one van de Kamp thought he had discovered in 1963.

Through the Eyes of Hubble

Through the Eyes of Hubble PDF

Author: R Naeye

Publisher: CRC Press

Published: 1997-09-01

Total Pages: 142

ISBN-13: 9780750304849

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Robert Naeye is renowned for his lucid contributions to Astronomy, the world's biggest selling astronomy magazine. In Through the Eyes of Hubble: The Birth, Life and Violent Death of Stars, he uses 100 striking color images from the Hubble Space Telescope to illuminate the mind-stretching story of how stars are born, live, and die. Although focusing on astrophysics, the account is compelling, equation free, and accessible to everyone. In addition, there are eight beautiful paintings to appreciate, including works by the most famous living space artist, Michael Carroll.

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