ASTR1102-002 (Extended Set Of…) Practice Questions for Exam #3 1
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2.5 Dimensional Radiative Transfer Modeling of Proto-Planetary Nebula Dust Shells with 2-DUST
PLANETARY NEBULAE: THEIR EVOLUTION AND ROLE IN THE UNIVERSE fA U Symposium, Vol. 209, 2003 S. Kwok, M. Dopita, and R. Sutherland, eds. 2.5 Dimensional Radiative Transfer Modeling of Proto-Planetary Nebula Dust Shells with 2-DUST Toshiya Ueta & Margaret Meixner Department of Astronomy, MC-221 , University of fllinois at Urbana-Champaign, Urbana, IL 61801, USA ueta@astro. uiuc.edu, [email protected]. edu Abstract. Our observing campaign of proto-planetary nebula (PPN) dust shells has shown that the structure formation in planetary nebu- lae (PNs) begins as early as the late asymptotic. giant branch (AGB) phase due to intrinsically axisymmetric superwind. We describe our latest numerical efforts with a multi-dimensional dust radiative transfer code, 2-DUST, in order to explain the apparent dichotomy of the PPN mor- phology at the mid-IR and optical, which originates most likely from the optical depth of the shell combined with the effect of inclination angle. 1. Axisymmetric PPN Shells and Single Density Distribution Model Since the PPN phase predates the period of final PN shaping due to interactions of the stellar winds, we can investigate the origin of the PN structure formation by observationally establishing the material distribution in the PPN shells, in which pristine fossil records of AGB mass loss histories are preserved in their benign circumstellar environment. Our mid-IR and optical imaging surveys of PPN candidates in the past several years (Meixner at al. 1999; Ueta et al. 2000) have revealed that (1) PPN shells are intrinsically axisymmetric most likely due to equatorially-enhanced superwind mass loss at the end of the AGB phase and (2) varying degrees of equatorial enhancement in superwind would result in different optical depths of the PPN shell, thereby heavily influencing the mid-IR and optical morphologies. -
FY08 Technical Papers by GSMTPO Staff
AURA/NOAO ANNUAL REPORT FY 2008 Submitted to the National Science Foundation July 23, 2008 Revised as Complete and Submitted December 23, 2008 NGC 660, ~13 Mpc from the Earth, is a peculiar, polar ring galaxy that resulted from two galaxies colliding. It consists of a nearly edge-on disk and a strongly warped outer disk. Image Credit: T.A. Rector/University of Alaska, Anchorage NATIONAL OPTICAL ASTRONOMY OBSERVATORY NOAO ANNUAL REPORT FY 2008 Submitted to the National Science Foundation December 23, 2008 TABLE OF CONTENTS EXECUTIVE SUMMARY ............................................................................................................................. 1 1 SCIENTIFIC ACTIVITIES AND FINDINGS ..................................................................................... 2 1.1 Cerro Tololo Inter-American Observatory...................................................................................... 2 The Once and Future Supernova η Carinae...................................................................................................... 2 A Stellar Merger and a Missing White Dwarf.................................................................................................. 3 Imaging the COSMOS...................................................................................................................................... 3 The Hubble Constant from a Gravitational Lens.............................................................................................. 4 A New Dwarf Nova in the Period Gap............................................................................................................ -
XIII Publications, Presentations
XIII Publications, Presentations 1. Refereed Publications E., Kawamura, A., Nguyen Luong, Q., Sanhueza, P., Kurono, Y.: 2015, The 2014 ALMA Long Baseline Campaign: First Results from Aasi, J., et al. including Fujimoto, M.-K., Hayama, K., Kawamura, High Angular Resolution Observations toward the HL Tau Region, S., Mori, T., Nishida, E., Nishizawa, A.: 2015, Characterization of ApJ, 808, L3. the LIGO detectors during their sixth science run, Classical Quantum ALMA Partnership, et al. including Asaki, Y., Hirota, A., Nakanishi, Gravity, 32, 115012. K., Espada, D., Kameno, S., Sawada, T., Takahashi, S., Ao, Y., Abbott, B. P., et al. including Flaminio, R., LIGO Scientific Hatsukade, B., Matsuda, Y., Iono, D., Kurono, Y.: 2015, The 2014 Collaboration, Virgo Collaboration: 2016, Astrophysical Implications ALMA Long Baseline Campaign: Observations of the Strongly of the Binary Black Hole Merger GW150914, ApJ, 818, L22. Lensed Submillimeter Galaxy HATLAS J090311.6+003906 at z = Abbott, B. P., et al. including Flaminio, R., LIGO Scientific 3.042, ApJ, 808, L4. Collaboration, Virgo Collaboration: 2016, Observation of ALMA Partnership, et al. including Asaki, Y., Hirota, A., Nakanishi, Gravitational Waves from a Binary Black Hole Merger, Phys. Rev. K., Espada, D., Kameno, S., Sawada, T., Takahashi, S., Kurono, Lett., 116, 061102. Y., Tatematsu, K.: 2015, The 2014 ALMA Long Baseline Campaign: Abbott, B. P., et al. including Flaminio, R., LIGO Scientific Observations of Asteroid 3 Juno at 60 Kilometer Resolution, ApJ, Collaboration, Virgo Collaboration: 2016, GW150914: Implications 808, L2. for the Stochastic Gravitational-Wave Background from Binary Black Alonso-Herrero, A., et al. including Imanishi, M.: 2016, A mid-infrared Holes, Phys. -
Planetary Nebulae Jacob Arnold AY230, Fall 2008
Jacob Arnold Planetary Nebulae Jacob Arnold AY230, Fall 2008 1 PNe Formation Low mass stars (less than 8 M) will travel through the asymptotic giant branch (AGB) of the familiar HR-diagram. During this stage of evolution, energy generation is primarily relegated to a shell of helium just outside of the carbon-oxygen core. This thin shell of fusing He cannot expand against the outer layer of the star, and rapidly heats up while also quickly exhausting its reserves and transferring its head outwards. When the He is depleted, Hydrogen burning begins in a shell just a little farther out. Over time, helium builds up again, and very abruptly begins burning, leading to a shell-helium-flash (thermal pulse). During the thermal-pulse AGB phase, this process repeats itself, leading to mass loss at the extended outer envelope of the star. The pulsations extend the outer layers of the star, causing the temperature to drop below the condensation temperature for grain formation (Zijlstra 2006). Grains are driven off the star by radiation pressure, bringing gas with them through collisions. The mass loss from pulsating AGB stars is oftentimes referred to as a wind. For AGB stars, the surface gravity of the star is quite low, and wind speeds of ~10 km/s are more than sufficient to drive off mass. At some point, a super wind develops that removes the envelope entirely, a phenomenon not yet fully understood (Bernard-Salas 2003). The central, primarily carbon-oxygen core is thus exposed. These cores can have temperatures in the hundreds of thousands of Kelvin, leading to a very strong ionizing source. -
Curriculum Vitae - 24 March 2020
Dr. Eric E. Mamajek Curriculum Vitae - 24 March 2020 Jet Propulsion Laboratory Phone: (818) 354-2153 4800 Oak Grove Drive FAX: (818) 393-4950 MS 321-162 [email protected] Pasadena, CA 91109-8099 https://science.jpl.nasa.gov/people/Mamajek/ Positions 2020- Discipline Program Manager - Exoplanets, Astro. & Physics Directorate, JPL/Caltech 2016- Deputy Program Chief Scientist, NASA Exoplanet Exploration Program, JPL/Caltech 2017- Professor of Physics & Astronomy (Research), University of Rochester 2016-2017 Visiting Professor, Physics & Astronomy, University of Rochester 2016 Professor, Physics & Astronomy, University of Rochester 2013-2016 Associate Professor, Physics & Astronomy, University of Rochester 2011-2012 Associate Astronomer, NOAO, Cerro Tololo Inter-American Observatory 2008-2013 Assistant Professor, Physics & Astronomy, University of Rochester (on leave 2011-2012) 2004-2008 Clay Postdoctoral Fellow, Harvard-Smithsonian Center for Astrophysics 2000-2004 Graduate Research Assistant, University of Arizona, Astronomy 1999-2000 Graduate Teaching Assistant, University of Arizona, Astronomy 1998-1999 J. William Fulbright Fellow, Australia, ADFA/UNSW School of Physics Languages English (native), Spanish (advanced) Education 2004 Ph.D. The University of Arizona, Astronomy 2001 M.S. The University of Arizona, Astronomy 2000 M.Sc. The University of New South Wales, ADFA, Physics 1998 B.S. The Pennsylvania State University, Astronomy & Astrophysics, Physics 1993 H.S. Bethel Park High School Research Interests Formation and Evolution -
Brown Dwarf: White Dwarf: Hertzsprung -Russell Diagram (H-R
Types of Stars Spectral Classifications: Based on the luminosity and effective temperature , the stars are categorized depending upon their positions in the HR diagram. Hertzsprung -Russell Diagram (H-R Diagram) : 1. The H-R Diagram is a graphical tool that astronomers use to classify stars according to their luminosity (i.e. brightness), spectral type, color, temperature and evolutionary stage. 2. HR diagram is a plot of luminosity of stars versus its effective temperature. 3. Most of the stars occupy the region in the diagram along the line called the main sequence. During that stage stars are fusing hydrogen in their cores. Various Types of Stars Brown Dwarf: White Dwarf: Brown dwarfs are sub-stellar objects After a star like the sun exhausts its nuclear that are not massive enough to sustain fuel, it loses its outer layer as a "planetary nuclear fusion processes. nebula" and leaves behind the remnant "white Since, comparatively they are very cold dwarf" core. objects, it is difficult to detect them. Stars with initial masses Now there are ongoing efforts to study M < 8Msun will end as white dwarfs. them in infrared wavelengths. A typical white dwarf is about the size of the This picture shows a brown dwarf around Earth. a star HD3651 located 36Ly away in It is very dense and hot. A spoonful of white constellation of Pisces. dwarf material on Earth would weigh as much as First directly detected Brown Dwarf HD 3651B. few tons. Image by: ESO The image is of Helix nebula towards constellation of Aquarius hosts a White Dwarf Helix Nebula 6500Ly away. -
The Formation of Brown Dwarfs 459
Whitworth et al.: The Formation of Brown Dwarfs 459 The Formation of Brown Dwarfs: Theory Anthony Whitworth Cardiff University Matthew R. Bate University of Exeter Åke Nordlund University of Copenhagen Bo Reipurth University of Hawaii Hans Zinnecker Astrophysikalisches Institut, Potsdam We review five mechanisms for forming brown dwarfs: (1) turbulent fragmentation of molec- ular clouds, producing very-low-mass prestellar cores by shock compression; (2) collapse and fragmentation of more massive prestellar cores; (3) disk fragmentation; (4) premature ejection of protostellar embryos from their natal cores; and (5) photoerosion of pre-existing cores over- run by HII regions. These mechanisms are not mutually exclusive. Their relative importance probably depends on environment, and should be judged by their ability to reproduce the brown dwarf IMF, the distribution and kinematics of newly formed brown dwarfs, the binary statis- tics of brown dwarfs, the ability of brown dwarfs to retain disks, and hence their ability to sustain accretion and outflows. This will require more sophisticated numerical modeling than is presently possible, in particular more realistic initial conditions and more realistic treatments of radiation transport, angular momentum transport, and magnetic fields. We discuss the mini- mum mass for brown dwarfs, and how brown dwarfs should be distinguished from planets. 1. INTRODUCTION form a smooth continuum with those of low-mass H-burn- ing stars. Understanding how brown dwarfs form is there- The existence of brown dwarfs was first proposed on the- fore the key to understanding what determines the minimum oretical grounds by Kumar (1963) and Hayashi and Nakano mass for star formation. In section 3 we review the basic (1963). -
Spring Semester 2010 Exam 3 – Answers a Planetary Nebula Is A
ASTR 1120H – Spring Semester 2010 Exam 3 – Answers PART I (70 points total) – 14 short answer questions (5 points each): 1. What is a planetary nebula? How long can a planetary nebula be observed? A planetary nebula is a luminous shell of gas ejected from an old, low- mass star. It can be observed for approximately 50,000 years; after that it its gases will have ceased to glow and it will simply fade from view. 2. What is a white dwarf star? How does a white dwarf change over time? A white dwarf star is a low-mass star that has exhausted all its nuclear fuel and contracted to a size roughly equal to the size of the Earth. It is supported against further contraction by electron degeneracy pressure. As a white dwarf ages, though, it will radiate, thereby cooling and getting less luminous. 3. Name at least three differences between Type Ia supernovae and Type II supernovae. Type Ia SN are intrinsically brighter than Type II SN. Type II SN show hydrogen emission lines; Type Ia SN don't. Type II SN are thought to arise from core collapse of a single, massive star. Type Ia SN are thought to arise from accretion from a binary companion onto a white dwarf star, pushing the white dwarf beyond the Chandrasekhar limit and causing a nuclear detonation that destroys the white dwarf. 4. Why was SN 1987A so important? SN 1987A was the first naked-eye SN in almost 400 years. It was the first SN for which a precursor star could be identified. -
SHAPING the WIND of DYING STARS Noam Soker
Pleasantness Review* Department of Physics, Technion, Israel The role of jets in the common envelope evolution (CEE) and in the grazing envelope evolution (GEE) Cambridge 2016 Noam Soker •Dictionary translation of my name from Hebrew to English (real!): Noam = Pleasantness Soker = Review A short summary JETS See review accepted for publication by astro-ph in May 2016: Soker, N., 2016, arXiv: 160502672 A very short summary JFM See review accepted for publication by astro-ph in May 2016: Soker, N., 2016, arXiv: 160502672 A full summary • Jets are unavoidable when the companion enters the common envelope. They are most likely to continue as the secondary star enters the envelop, and operate under a negative feedback mechanism (the Jet Feedback Mechanism - JFM). • Jets: Can be launched outside and Secondary inside the envelope star RGB, AGB, Red Giant Massive giant primary star Jets Jets Jets: And on its surface Secondary star RGB, AGB, Red Giant Massive giant primary star Jets A full summary • Jets are unavoidable when the companion enters the common envelope. They are most likely to continue as the secondary star enters the envelop, and operate under a negative feedback mechanism (the Jet Feedback Mechanism - JFM). • When the jets mange to eject the envelope outside the orbit of the secondary star, the system avoids a common envelope evolution (CEE). This is the Grazing Envelope Evolution (GEE). Points to consider (P1) The JFM (jet feedback mechanism) is a negative feedback cycle. But there is a positive ingredient ! In the common envelope evolution (CEE) more mass is removed from zones outside the orbit. -
The Potential of Planets Orbiting Red Dwarf Stars to Support Oxygenic Photosynthesis and Complex Life
1 The Potential of Planets Orbiting Red Dwarf Stars to Support Oxygenic Photosynthesis and Complex Life Joseph Gale1 and Amri Wandel2 The Institute of Life Sciences1and The Racach Institute of Physics2, The Hebrew University of Jerusalem, 91904, Israel. [email protected] [email protected] Accepted for publication in the International Journal of Astrobiology Abstract We review and reassess the latest findings on the existence of extra-solar system planets and their potential of having environmental conditions that could support Earth-like life. Within the last two decades, the multi-millennial question of the existence of extra-Solar- system planets has been resolved with the discovery of numerous planets orbiting nearby stars, many of which are Earth-sized (and some even with moderate surface temperatures). Of particular interest in our search for clement conditions for extra-solar system life are planets orbiting Red Dwarf (RD) stars, the most numerous stellar type in the Milky Way galaxy. We show that including RDs as potential life supporting host stars could increase the probability of finding biotic planets by a factor of up to a thousand, and reduce the estimate of the distance to our nearest biotic neighbor by up to 10. We argue that multiple star systems need to be taken into account when discussing habitability and the abundance of biotic exoplanets, in particular binaries of which one or both members are RDs. Early considerations indicated that conditions on RD planets would be inimical to life, as their Habitable Zones (where liquid water could exist) would be so close as to make planets tidally locked to their star. -
The MUSE View of the Planetary Nebula NGC 3132? Ana Monreal-Ibero1,2 and Jeremy R
A&A 634, A47 (2020) Astronomy https://doi.org/10.1051/0004-6361/201936845 & © ESO 2020 Astrophysics The MUSE view of the planetary nebula NGC 3132? Ana Monreal-Ibero1,2 and Jeremy R. Walsh3,?? 1 Instituto de Astrofísica de Canarias (IAC), 38205 La Laguna, Tenerife, Spain e-mail: [email protected] 2 Universidad de La Laguna, Dpto. Astrofísica, 38206 La Laguna, Tenerife, Spain 3 European Southern Observatory, Karl-Schwarzschild Strasse 2, 85748 Garching, Germany Received 4 October 2019 / Accepted 6 December 2019 ABSTRACT Aims. Two-dimensional spectroscopic data for the whole extent of the NGC 3132 planetary nebula have been obtained. We deliver a reduced data-cube and high-quality maps on a spaxel-by-spaxel basis for the many emission lines falling within the Multi-Unit Spectroscopic Explorer (MUSE) spectral coverage over a range in surface brightness >1000. Physical diagnostics derived from the emission line images, opening up a variety of scientific applications, are discussed. Methods. Data were obtained during MUSE commissioning on the European Southern Observatory (ESO) Very Large Telescope and reduced with the standard ESO pipeline. Emission lines were fitted by Gaussian profiles. The dust extinction, electron densities, and temperatures of the ionised gas and abundances were determined using Python and PyNeb routines. 2 Results. The delivered datacube has a spatial size of 6300 12300, corresponding to 0:26 0:51 pc for the adopted distance, and ∼ × ∼ 1 × a contiguous wavelength coverage of 4750–9300 Å at a spectral sampling of 1.25 Å pix− . The nebula presents a complex reddening structure with high values (c(Hβ) 0:4) at the rim. -
Reionization the End of the Universe
Reionization The End of the Universe How will the Universe end? Is this the only Universe? What, if anything, will exist after the Universe ends? Universe started out very hot (Big Bang), then expanded: Some say the world will end in fire, Some say in ice. From what I’ve tasted of desire I hold with those who favor fire. But if I had to perish twice, I think I know enough of hate To know that for destruction ice is also great And would suffice. How it ends depends on the geometry of the Universe: Robert Frost 2) More like a saddle than a sphere, with curvature in the opposite The Geometry of Curved Space sense in different dimensions: "negative" curvature. Possibilities: Sum of the 1) Space curves back on itself (like a sphere). "Positive" curvature. Angles < 180 Sum of the Angles > 180 3) A more familiar flat geometry. Sum of the Angles = 180 1 The Geometry of the Universe determines its fate Case 1: high density Universe, spacetime is positively curved Result is “Big Crunch” Fire The Five Ages of the Universe Cases 2 or 3: open Universe (flat or negatively curved) 1) The Primordial Era 2) The Stelliferous Era 3) The Degenerate Era 4) The Black Hole Era Current measurements favor an open Universe 5) The Dark Era Result is infinite expansion Ice 1. The Primordial Era: 10-50 - 105 y The Early Universe Inflation Something triggers the Creation of the Universe at t=0 A problem with microwave background: Microwave background reaches us from all directions.