Newsletter 97 ª October 1999 NEWSLETTER
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NASA's Goddard Space Flight Center Laboratory for High Energy
1 NASA’s Goddard Space Flight Center Laboratory for High Energy Astrophysics Greenbelt, Maryland 20771 @S0002-7537~99!00301-7# This report covers the period from July 1, 1997 to June 30, Toshiaki Takeshima, Jane Turner, Ken Watanabe, Laura 1998. Whitlock, and Tahir Yaqoob. This Laboratory’s scientific research is directed toward The following investigators are University of Maryland experimental and theoretical research in the areas of X-ray, Scientists: Drs. Keith Arnaud, Manuel Bautista, Wan Chen, gamma-ray, and cosmic-ray astrophysics. The range of inter- Fred Finkbeiner, Keith Gendreau, Una Hwang, Michael Loe- ests of the scientists includes the Sun and the solar system, wenstein, Greg Madejski, F. Scott Porter, Ian Richardson, stellar objects, binary systems, neutron stars, black holes, the Caleb Scharf, Michael Stark, and Azita Valinia. interstellar medium, normal and active galaxies, galaxy clus- Visiting scientists from other institutions: Drs. Vadim ters, cosmic-ray particles, and the extragalactic background Arefiev ~IKI!, Hilary Cane ~U. Tasmania!, Peter Gonthier radiation. Scientists and engineers in the Laboratory also ~Hope College!, Thomas Hams ~U. Seigen!, Donald Kniffen serve the scientific community, including project support ~Hampden-Sydney College!, Benzion Kozlovsky ~U. Tel such as acting as project scientists and providing technical Aviv!, Richard Kroeger ~NRL!, Hideyo Kunieda ~Nagoya assistance to various space missions. Also at any one time, U.!, Eugene Loh ~U. Utah!, Masaki Mori ~Miyagi U.!, Rob- there are typically between twelve and eighteen graduate stu- ert Nemiroff ~Mich. Tech. U.!, Hagai Netzer ~U. Tel Aviv!, dents involved in Ph.D. research work in this Laboratory. Yasushi Ogasaka ~JSPS!, Lev Titarchuk ~George Mason U.!, Currently these are graduate students from Catholic U., Stan- Alan Tylka ~NRL!, Robert Warwick ~U. -
NASA Goddard Space Flight Center Laboratory for High Energy Astrophysics Greenbelt, Maryland 20771
1 NASA Goddard Space Flight Center Laboratory for High Energy Astrophysics Greenbelt, Maryland 20771 This report covers the period from July 1, 2002 to June Stephen Henderson, Hans Krimm, John Krizmanic, Jeongin 30, 2003. Lee, John Lehan, James Lochner, Thomas McGlynn, Paul This Laboratory’s scientific research is directed toward McNamara, Alex Moiseev, Koji Mukai, James Reeves, Na- experimental and theoretical investigations in the areas of dine Saudraix, Chris Shrader, Steven Snowden, Yang Soong, X-ray, gamma-ray, gravitational wave and cosmic-ray astro- Martin Still, Steve Sturner, and Vigdor Teplitz. physics. The range of interests of the scientists includes the The following investigators are University of Maryland Sun and the solar system, stellar objects, binary systems, Scientists: Drs. Keith Arnaud, David Band ͑UMBC͒, Simon neutron stars, black holes, the interstellar medium, normal Bandler, Patricia Boyd ͑UMBC͒, John Cannizzo ͑UMBC͒, and active galaxies, galaxy clusters, cosmic ray particles, David Davis ͑UMBC͒, Ian George ͑UMBC͒, Masaharu gravitational wave astrophysics, extragalactic background ra- Hirayama ͑UMBC͒, Una Hwang, Yasushi Ikebe ͑UMBC͒, diation, and cosmology. Scientists and engineers in the Kip Kuntz ͑UMBC͒, Mark Lindeman, Michael Loewenstein, Laboratory also serve the scientific community, including Craig Markwardt, Julie McEnery ͑UMBC͒, Igor Moskalenko project support such as acting as project scientists and pro- ͑UMBC͒, Chee Ng, Patrick Palmeri, Dirk Petry ͑UMBC͒, viding technical assistance for various space missions. Also Christopher Reynolds, Ian Richardson, and Jane Turner at any one time, there are typically between ten and fifteen ͑UMBC͒. graduate students involved in Ph.D. research work in this Visiting scientists from other institutions: Drs. Hilary Laboratory. -
THE NEAREST GROUP of GALAXIES Sidney Van Den Bergh
THE NEAREST GROUP OF GALAXIES Sidney van den Bergh Dominion Astrophysical Observatory Herzberg Institute of Astrophysics National Research Council 5071 West Saanich Road Victoria, British Columbia, V8X 4M6, Canada ABSTRACT The small Antlia-Sextans clustering of galaxies is located at a distance of only 1.36 Mpc from the Sun, and 1.72 Mpc from the adopted barycenter of the Local Group. The latter value is significantly greater than the radius of the zero- velocity surface of the Local Group which, for an assumed age of 14 Gyr, has Ro = 1.18 " 0.15 Mpc. This, together with the observation that the members of the Ant-Sex group have a mean redshift of +114 " 12 km s-1 relative to the centroid of the Local Group, suggests that the Antlia-Sextans group is not bound to our Local Group, and that it is expanding with the Hubble flow. If this conclusion is correct, then Antlia-Sextans may be the nearest external clustering of galaxies. The total galaxian population of the Ant-Sex group is ~ 1/5 that of the Local Group. However, the integrated luminosity of Ant-Sex is two orders of magnitude lower than that of the Local Group. Subject headings: Galaxies - clusters: individual (Antlia-Sextans) - 2 - 1. INTRODUCTION A detailed discussion of the galaxies that appear to be located along the outer fringes of the Local Group has been given by van den Bergh (1994, 2000). From these data the Local Group is found to have 32 probable members that are located within 1.0 Mpc of its barycenter. -
Newsletter 99 ª March 2000 NEWSLETTER
Newsletter 99 ª March 2000 NEWSLETTER The American Astronomical Societys2000 Florida Avenue, NW, Suite 400sWashington, DC [email protected] ROCHESTER PRESIDENT’S COLUMN HOSTS Bob Gehrz, President, [email protected] AAS The Budget is Here: Start_Early@Home On February 7, President Clinton submitted a FY2001 budget SUMMER request which includes dramatic increases for the science MEETING funding agencies such as NASA and NSF. Well before this, at Caltech, he emphasized the need to support all scientific LOC members at the research and the interconnectedness of the physical and life University of Rochester sciences. Congress also appears to be acknowledging the (UR), and the Rochester importance of basic science research. Institute of Technology (RIT) This year, we have a chance, are delighted to welcome the if we get started now, 196th Meeting of the AAS to support proactively to Rochester, NY from a substantial increase 4–8 June 2000. The ...the best way to in science budgets third largest urban influence a budget outcome rather than be area in New York, forced to react to Rochester is home to a variety of industries and is to visit the home district a potential disaster research centers that support astronomy — from those offices of congressional created by partisan at UR and RIT that develop detector arrays for space politics, as we were missions and for ground-based astronomy; to the representatives last year. Luckily, Eastman Kodak Company, that developed the mirror for science is a non-partisan Chandra and Keck telescopes; to the Richardson Grating issue and is likely to enjoy Laboratory, that produces ultra-large gratings, such as those for continued support no matter who the Subaru Telescope; and to UR’s Laboratory for Laser wins the coming Presidential election. -
Future Probes of the Neutron Star Equation of State Using X-Ray Bursts
I Future Probes of the Neutron Star Equation of State Using X-ray Bursts Tod E. Strohmayer Luboratory for High Energy Astrophysics, NASA’s Goddard Space Flight Center; Greenbelt, MD 20771 Abstract. Observations with NASA’s Rossi X-ray Timing Explorer (RXTE)have resulted in the discovery of fast (200 - 600 Hz), coherent X-ray intensity oscillations (hereafter, ‘%urstoscillations”) during thermonuclear X-ray bursts from 12 low mass X-ray binaries (LMXBs). Although many of their detailed properties remain to be fully understood, it is now beyond doubt that these oscillations result from spin modulation of the thermonuclear burst flux from the neutron star surface. Among the new timing phenomena revealed by RXTE the burst oscillations are perhaps the best understood, in the sense that many of their properties can be explained in the framework of this relatively simple model. Because of this, detailed modelling of burst oscillations can be an extremely powerful probe of neutron star structure, and thus the equation of state (EOS) of supra- nuclear density matter. Both the compactness parameter /3 = CM/SR,and the surface velocity, v,,, = SZSPi,R, are encoded in the energy-dependent amplitude and shape of the modulation pulses. The new discoveries have spurred much new theoretical work on thermonuclear burning and propagation on neutron stars, so that in the near future it is not unreasonable to think that detailed physical models of the time dependent flux from burning neutron stars will be available for comparison with the observed pulse profiles from a future, large collecting area X-ray timing observatory. In addition, recent high resolution burst spectroscopy with XMM/Newton suggests the presence of redshifted absorption lines from the neutron star surface during bursts. -
609-622, July 1991 PUBLICATIONS of the ASTRONOMICAL
Publications OFTHE Astronomical SociE-noFTHK Pacific 103: 609-622, July 1991 PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC Vol. 103 July 1991 No. 665 THE STELLAR POPULATIONS OF M 331 SIDNEY VAN DEN BERGH Dominion Astrophysical Observatory, National Research Council of Canada 5071 West Saanich Road, Victoria, BC V8X 4M6, Canada Received 199 ABSTRACT A review is given of present ideas on the evolution and stellar content of the Triangulum nebula = M 33 = NGC 598. A distance modulus of (m — M)() = 24.5 ± 0.2 (D = 795 ± 75 kpc) and a Galactic foreground reddening £ß_v = 0.07, from which Mv = —18.87, are adopted throughout this paper. The disk of M 33 is embedded in a halo of globular clusters, metal-poor red giants, and RR Lyrae stars. Its nuclear bulge component is weak (Mv > -14). This suggests that the halos of galaxies are not extensions of their bulges to large radii. The ages of M 33 clusters do not appear to exhibit a hiatus in their star-forming history like that which is observed in the Large Magellanic Cloud. Young and intermediate-age clusters with luminosities rivaling the populous clusters in the LMC are rare in M 33. The integrated light of the semistellar nucleus of M 33, which contains the strongest X-ray source in the Local Group, is dominated by a young metal-rich population. At optical wavelengths the disk scale length of M 33 is 9.'6, which is similar to the 9.'9 scale length of OB associations. The ratio of the nova rate in M 33 to that in M 31 is approximately equal to the ratio of their luminosities. -
Astro2010: the Astronomy and Astrophysics Decadal Survey
Astro2010: The Astronomy and Astrophysics Decadal Survey Notices of Interest 1. 4 m space telescope for terrestrial planet imaging and wide field astrophysics Point of Contact: Roger Angel, University of Arizona Summary Description: The proposed 4 m telescope combines capabilities for imaging terrestrial exoplanets and for general astrophysics without compromising either. Extremely high contrast imaging at very close inner working angle, as needed for terrestrial planet imaging, is accomplished by the powerful phase induced amplitude apodization method (PIAA) developed by Olivier Guyon. This method promises 10-10 contrast at 2.0 l/D angular separation, i.e. 50 mas for a 4 m telescope at 500 nm wavelength. The telescope primary mirror is unobscured with off-axis figure, as needed to achieve such high contrast. Despite the off-axis primary, the telescope nevertheless provides also a very wide field for general astrophysics. A 3 mirror anastigmat design by Jim Burge delivers a 6 by 24 arcminute field whose mean wavefront error of 12 nm rms, i.e.diffraction limited at 360 nm wavelength. Over the best 10 square arcminutes the rms error is 7 nm, for diffraction limited imaging at 200 nm wavelength. Any of the instruments can be fed by part or all of the field, by means of a flat steering mirror at the exit pupil. To allow for this, the field is curved with a radius equal to the distance from the exit pupil. The entire optical system fits in a 4 m diameter cylinder, 8 m long. Many have considered that only by using two spacecraft, a conventional on-axis telescope and a remote occulter, could high contrast and wide field imaging goals be reconciled. -
The Hertzsprung-Russell Diagram of Metal-Poor Disk Stars
THE HERTZSPRUNG-RUSSELL DIAGRAM OF METAL-POOR DISK STARS Sidney van den Bergh David Dunlap Observatory A quarter of a century ago Keenan and Keller (1953) showed that the majority of high-velocity stars near the Sun outline a Hertzsprung-Russell diagram similar to that of old Population I. This result, which did not appear to fit into Baade1s (19ΛΛ) two- population model of the Galaxy was ignored (except by Roman 1965) for the next two decades. Striking confirmation of the results of Keenan and Keller was, however, obtained by Hartwick and Hesser (1972). Their work appears to show that high-velocity field stars with an ultraviolet excess (which measures Fe/H) of 6(U-B) ^ +0T11 lie on a red giant branch that is more than a magnitude fainter than the giant branch of the strong-lined globular cluster 47 Tue for which <S(U-B) ^ +0Tl0. Furthermore Démarqué and McClure (1977) show that the red giants in the old metal poor [S(U-B) ^ +0T11] open cluster NGC 2^20 are significantly fainter than are those in 4-7 Tue. Calculations by these authors show that the observed differences between the giants in Λ7 Tue and in NGC 24-20 can be explained if either (l) 4-7 Tue is richer in helium than NGC 24-20 by ΔΥ £ 0.1 or (2) if Λ7 Tue has a ten times lower value of Z(CNO) than does NGC 2Λ20. Presently available chemical abundance determinations for galactic disk and halo stars do not allow one to make a clear-cut choice between these two alternatives. -
Women in Astronomy III (2009) Proceedings
W OMEN I N A STRONOMY AND S PACE S CIENCE Meeting the Challenges of an Increasingly Diverse Workforce Proceedings from the conference held at The Inn and Conference Center University of Maryland University College October 21—23, 2009 Edited by Anne L. Kinney, Diana Khachadourian, Pamela S. Millar and Colleen N. Hartman I N M EMORIAM Dr. Beth A. Brown 1969-2008 i D e d i c a t i o n Dedication to Beth Brown Fallen Star Howard E. Kea, NASA/GSFC She lit up a room with her wonderful smile; she made everyone in her presence feel that they were important. On October 5, 2008 one of our rising stars in astronomy had fallen. Dr. Beth Brown was an Astrophysicist in the Science and Exploration Directorate at NASA’s Goddard Space Flight Center. Beth was always fascinated by space: she grew up watching Star Trek and Star Wars, which motivated her to become an astronaut. However, her eyesight prevented her from being eligible for astronaut training, which led to her pursuing the stars through astronomy. Beth pursued her study of the stars more seriously at Howard University where she majored in physics and astronomy. Upon learning that her nearsightedness would limit her chances of becoming an astronaut, Beth’s love for astronomy continued to grow and she graduated summa cum laude from Howard University. Beth continued her education at the University of Michigan in Ann Arbor. There she received a Master’s Degree in Astronomy in 1994 on elliptical galaxies and she obtained her Ph.D. -
Reflections on the Rossi X-Ray Timing Explorer” © 3/19/13 Hale Bradt
“Reflections on the Rossi X-ray Timing Explorer” © 3/19/13 Hale Bradt Reflections on the Rossi X-ray Timing Explorer A Personal Account by Hale Bradt An expanded version of the banquet talk at the Symposium, “Exploring Physics with Neutron Stars” in honor of the 65th birthday of Fred K. Lamb Tucson, Arizona, 18 Nov. 2010 Introduction When I retired in 2001 I had to reduce my office footprint because I was to share the office with Gordon Pettengill, another faculty retiree. Upon coming across files relating to the RXTE mission, it occurred to me that the 20 years we spent in bringing this mission to fruition (i.e. launch) was quite interesting and that the documents and correspondence in my files might well be donated to the MIT Archives. I thus left this pile, about 12 inches high, on top of one of my file cabinets with the intention of organizing it a bit and providing a brief contextual document to accompany them. Some months ago, Dimitrios Psaltis called and asked me to give a talk on the selling of the RXTE mission, and I said, “Why me and why that?” “Well,” he said, “this Symposium is to honor Fred Lamb and he was instrumental in helping bring about the mission. I recall that, at a conference in Rome, over dinner or lunch, you told me all about the adventures of getting RXTE into orbit and a lot of it was very funny, and I thought it would be appropriate for this symposium.” So, I agreed, and realized this was the goad I needed to address that pile of documents that had been untouched for 9 years. -
Arxiv:Astro-Ph/0305042 V2 12 May 2003 Lu,M2 G25 G 82 G 8,I 63Adnc17t Th to 147 NGC and 1613 IC 185, NGC Clou 6822, Magellanic NGC As Large NGC205, He the M32, field”
HISTORY OF THE LOCAL GROUP SIDNEY van den BERGH Dominion Astrophysical Observatory Herzberg Institute of Astrophysics National Research Council of Canada 5071 West Saanich Road, Victoria, BC, Canada V9E 2E7 email: [email protected] ABSTRACT It is suggested that M31 was created by the early merger, and subsequent violent relaxation, of two or more massive metal-rich ancestral galaxies within the core of the Andromeda subgroup of the Local Group. On the other hand the evolution of the main body of the Galaxy appears to have been dominated by the collapse of a single ancestral object, that subsequently evolved by capturing a halo of small metal-poor companions. It remains a mystery why the globular cluster systems surrounding galaxies like M33 and the LMC exhibit such striking differences in evolutionary history. It is argued that the first generation of globular clusters might have been formed nearly simultaneously in all environments by the strong pressure increase that accompanied cosmic reionization. On the other hand subsequent generations of globulars may have formed during starbursts that were triggered by collisions and mergers of gas rich galaxies. The fact that the [G]alactic system is a member of a group is a very fortunate accident. arXiv:astro-ph/0305042 v2 12 May 2003 Hubble (1936, p.125) 1. INTRODUCTION According to Greek mythology the goddess of wisdom, Pallas Athene, emerged clad in full armor after Hephaestus split open Zeus’s head. In much the same way the Local Group sprang forth suddenly, and almost complete, in Chapter VI of The Realm of the Nebulae (Hubble 1936, pp. -
Headnews/Headnews.May01.Html
HEAD - Newsletter No. 78, May 2001 file:///D|/H E A D/Web/headnews/headnews.may01.html HEADNEWS: THE ELECTRONIC NEWSLETTER OF THE HIGH ENERGY ASTROPHYSICS DIVISION OF THE AAS Newsletter No. 78, May 2001 IN THIS ISSUE: 1. Notes from the Editor - Paul Hertz 2. Minoru Oda (1923-2001) - Lynn Cominsky 3. Reuven Ramaty (1937-2001) - NASA Press Release 4. HEAD News: 2000 and 2001 Rossi Prizes - Lynn Cominsky 5. News from NASA Headquarters - Paul Hertz Alan Bunner to Retire Office of Space Science to Streamline its Organization Opportunity in Astrophysics at NASA Headquarters Cosmic Journeys Update Research Program Deadlines in 2001 Explorer Program Update: SMEX Explorer Program Update: MIDEX 6. HEAD in the News - Lynn Cominsky and Megan Watzke News from the HEAD Meeting in Honolulu News from the San Diego AAS Meeting News from Gamma 2001 Other Chandra News News from RXTE News from XMM 7. EUVE Completes Mission - Brett Stroozas and Roger Malina 8. RXTE News - Jean Swank 9. Chandra X-ray Observatory Status - Belinda Wilkes 10. High Energy Transient Explorer (HETE) - George Ricker 11. XMM-Newton Updates - Ilana Harrus 12. HESSI Ready for Launch - David Smith 13. Swift Mission News - Lynn Cominsky 14. GLAST Mission News - Lynn Cominsky 15. Chandra Fellows Named - Megan Watzke 16. Meeting Announcements: High Energy Universe at Sharp Focus (16-18 July @ St. Paul, MN) Statistical Challenges in Modern Astronomy III (18-21 July @ State College, PA) Two Years of Science with Chandra (5-7 September @ Washington, DC) 1 of 26 6/3/01 11:35 PM HEAD - Newsletter No. 78, May 2001 file:///D|/H E A D/Web/headnews/headnews.may01.html X-ray Astronomy School (10-12 September @ Greenbelt, MD) Gamma Ray Burst and Afterglow Astronomy 2001 (5-9 November @ Woods Hole, MA) New Visions of the X-ray Universe in the XMM_Newton and Chandra era (26-30 November 2001 @ ESTEC, Noordwijk, Netherlands) from the Editor - Paul Hertz, HEAD Secretary-Treasurer, Notes [email protected], 202-358-0986 Beginning this month, HEAD will only be delivering the table-of-contents for HEADNEWS into your mailbox.