Download or read book A Hot White Dwarf Luminosity Function from the Sloan Digital Sky Survey written by Jurek Krzesiński and published by . This book was released on 2009 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aims. We present a hot white dwarf (WD) luminosity function (LF) using data taken from the Sloan Digital Sky Survey (SDSS) Data Release 4. We present and discuss a combined LF, along with separate DA and non-DA as LFs. We explore the completeness of our LFs and interpret a sudden drop in the non-DA LF near 2 M-bol as a transition of the non-DA WD atmosphere into the DA one during WD evolution. Our LF extends roughly between -0.5 M-bol 7 or equivalently, [around] 120 000 K T-eff '25 000 K. Our LF should now be useful for estimates of recent star formation and for studies of neutrino and other potential particle emission losses in hot WDs. Methods: To create a sample whose completeness can be characterized fully, we used stars whose spectra were obtained via the SDSS's 'hot standard' target selection criteria. The hot standard stars were purposefully targeted to a high level of completeness by the SDSS for calibration purposes. We are fortunate that many of them are hot white dwarfs stars. We further limited the sample to stars with fitted temperatures exceeding 23 500 K and log(g)> 7.0. We determined stellar distances for our sample based on their absolute SDSS g filter magnitudes, derived from WD stellar atmosphere model fits to the SDSS stellar spectra. Results: We compared our LF with those of other researchers where overlap occurs; however, our LFs are unique in their extension to the most luminous/hottest WDs. The cool end of our LF connects with the hot end of previously determined SDSS WD LFs and agreement here is quite good. It is also good with previous non-SDSS WD LFs. We note distinct differences between the DA and non-DA LFs and discuss the reliability of the DA LF at its hot end. We have extended the range of luminosities covered in the most recent WD LFs. The SDSS sample is understood quite well and its exploration should contribute to a number of new insights into early white dwarf evolution.
Download or read book White Dwarf Luminosity Functions from Sloan Digital Sky Survey Spectra written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lettre l diteur de l Almanach des Muses written by and published by . This book was released on 1770 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Luminosity Function for White Dwarfs in the SuperCOSMOS Sky Survey written by Nicholas Rowell and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Luminosity Function for White Dwarfs in the SuperCOSMOS Sky Survey written by Nicholas Robertson Rowell and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unlocking the Secrets of White Dwarf Stars written by Hugh M. Van Horn and published by Springer. This book was released on 2014-11-14 with total page 335 pages. Available in PDF, EPUB and Kindle. Book excerpt: White dwarfs, each containing about as much mass as our Sun but packed into a volume about the size of Earth, are the endpoints of evolution for most stars. Thousands of these faint objects have now been discovered, though only a century ago only three were known. They are among the most common stars in the Milky Way Galaxy, and they have become important tools in understanding the universe. Yet a century ago only three white dwarfs were known. The existence of these stars completely baffled the scientists of the day, and solving the mysteries of these strange objects required revolutionary advances in science and technology, including the development of quantum physics, the construction and utilization of large telescopes, the invention of the digital computer, and the ability to make astronomical observations from space. This book tells the story of the growth in our understanding of white dwarf stars, set within the context of the relevant scientific and technological advances. Part popular science, part historical narrative, this book is authored by one of the astrophysicists who participated directly in uncovering some of the secrets of white dwarf stars.
Download or read book Modern Statistical Methods for Astronomy written by Eric D. Feigelson and published by Cambridge University Press. This book was released on 2012-07-12 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern Statistical Methods for Astronomy: With R Applications.
Download or read book Asteroseismology in the Kepler Era written by Andrzej S. Baran and published by Frontiers Media SA. This book was released on 2021-10-13 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 15th European Workshop on White Dwarfs written by Ralf Napiwotzki and published by . This book was released on 2007 with total page 718 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Astrophysics in a Nutshell written by Dan Maoz and published by Princeton University Press. This book was released on 2016-02-23 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ideal one-semester astrophysics introduction for science undergraduates—now expanded and fully updated Winner of the American Astronomical Society's Chambliss Award, Astrophysics in a Nutshell has become the text of choice in astrophysics courses for science majors at top universities in North America and beyond. In this expanded and fully updated second edition, the book gets even better, with a new chapter on extrasolar planets; a greatly expanded chapter on the interstellar medium; fully updated facts and figures on all subjects, from the observed properties of white dwarfs to the latest results from precision cosmology; and additional instructive problem sets. Throughout, the text features the same focused, concise style and emphasis on physics intuition that have made the book a favorite of students and teachers. Written by Dan Maoz, a leading active researcher, and designed for advanced undergraduate science majors, Astrophysics in a Nutshell is a brief but thorough introduction to the observational data and theoretical concepts underlying modern astronomy. Generously illustrated, it covers the essentials of modern astrophysics, emphasizing the common physical principles that govern astronomical phenomena, and the interplay between theory and observation, while also introducing subjects at the forefront of modern research, including black holes, dark matter, dark energy, and gravitational lensing. In addition to serving as a course textbook, Astrophysics in a Nutshell is an ideal review for a qualifying exam and a handy reference for teachers and researchers. The most concise and current astrophysics textbook for science majors—now expanded and fully updated with the latest research results Contains a broad and well-balanced selection of traditional and current topics Uses simple, short, and clear derivations of physical results Trains students in the essential skills of order-of-magnitude analysis Features a new chapter on extrasolar planets, including discovery techniques Includes new and expanded sections and problems on the physics of shocks, supernova remnants, cosmic-ray acceleration, white dwarf properties, baryon acoustic oscillations, and more Contains instructive problem sets at the end of each chapter Solutions manual (available only to professors)
Download or read book 14th European Workshop on White Dwarfs written by Detlev Koester and published by . This book was released on 2005 with total page 722 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling the White Dwarf Luminosity Function written by Rick Navarro and published by . This book was released on 2012 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Results on the White Dwarf Luminosity Function written by and published by . This book was released on 1994 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stars as Laboratories for Fundamental Physics written by Georg G. Raffelt and published by University of Chicago Press. This book was released on 1996-05 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt: Much of what we know about neutrinos is revealed by astronomical observations, and the same applies to the axion, a conjectured new particle that is a favored candidate for the main component of the dark matter of the universe.
Download or read book Studies of Hot White Dwarfs and Instrumentation for Stellar Extreme Ultraviolet Astronomy written by David Starr Finley and published by . This book was released on 1988 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Nearby Old Halo White Dwarf Candidate from the Sloan Digital Sky Survey written by and published by . This book was released on 2008 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report the discovery of a nearby old halo white dwarf (WD) candidate from the Sloan Digital Sky Survey (SDSS). SDSS J110217.48+411315.4 has a proper motion of 1'.75 yr-1 and redder optical colors than all other known featureless (type DC) WDs. We present SDSS imaging and spectroscopy of this object, along with near-infrared photometry obtained at the United Kingdom Infrared Telescope (UKIRT). Fitting its photometry with up-to-date model atmospheres, we find that its overall spectral energy distribution is fit reasonably well with a pure-hydrogen composition and Teff H 3800 K (assuming log g = 8). This temperature and gravity would place this WD at 35 pc from the Sun with a tangential velocity of 290 km s 1 and space velocities consistent with halo membership; furthermore, its combined main-sequence and WD cooling age would be H11 Gyr. However, if this object is a massive WD, it could be a younger object with a thick disk origin. Whatever its origin, the optical colors of this object are redder than predicted by any current pure-hydrogen, pure-helium, or mixed hydrogen helium atmospheric model, indicating that there remain problems in our understanding of the complicated physics of the dense atmospheres of cool WDs.
Download or read book Recueil factice d articles de presse concernant Heinrich Sch tz et Kurt Spanich written by and published by . This book was released on with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
