The Search for Stellar Coronal Mass Ejections
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Harpspol Proposal by C. Neiner
European Organisation for Astronomical Research in the Southern Hemisphere OBSERVING PROGRAMMES OFFICE • Karl-Schwarzschild-Straße 2 • D-85748 Garching bei M¨unchen • e-mail: [email protected] • Tel. : +49 89 320 06473 APPLICATION FOR OBSERVING TIME PERIOD: 95A Important Notice: By submitting this proposal, the PI takes full responsibility for the content of the proposal, in particular with regard to the names of CoIs and the agreement to act according to the ESO policy and regulations, should observing time be granted. 1. Title Category: D{3 Spectropolarimetric observations of BRITE asteroseismic targets: a complete census of magnetic fields in bright stars up to V=4 2. Abstract / Total Time Requested Total Amount of Time: 6 nights VM, 0 hours SM This program aims at observing in circular spectropolarimetry all (yet unobserved) targets of the BRITE constellation of nano-satellites for asteroseismology, i.e. all stars brighter than V=4. They are mainly massive stars and evolved cool stars. Time has already been awarded at CFHT with ESPaDOnS and at TBL with Narval to observe the targets with a declination above -45◦. We propose to observe 104 targets below -45◦ with HarpsPol. Time has already been allocated in P94 for 51 targets. We request here the remaining 53 targets. These data will allow us to (1) obtain a complete and unbiased census of magnetic fields of all stars brighter than V=4, (2) determine the fundamental parameters of all BRITE targets, to constrain the seismic models of BRITE observations; (3) discover new magnetic stars and thus constrain their seismic models even further. -
NSF Current Newsletter Highlights Research and Education Efforts Supported by the National Science Foundation
March 2012 Each month, the NSF Current newsletter highlights research and education efforts supported by the National Science Foundation. If you would like to automatically receive notifications by e-mail or RSS when future editions of NSF Current are available, please use the links below: Subscribe to NSF Current by e-mail | What is RSS? | Print this page | Return to NSF Current Archive Robotic Surgery Systems Shipped to Medical Research Centers A set of seven identical advanced robotic-surgery systems produced with NSF support were shipped last month to major U.S. medical research laboratories, creating a network of systems using a common platform. The network is designed to make it easy for researchers to share software, replicate experiments and collaborate in other ways. Robotic surgery has the potential to enable new surgical procedures that are less invasive than existing techniques. The developers of the Raven II system made the decision to share it as the best way to move the field forward--though it meant giving competing laboratories tools that had taken them years to develop. "We decided to follow an open-source model, because if all of these labs have a common research platform for doing robotic surgery, the whole field will be able to advance more quickly," said Jacob Rosen, Students with components associate professor of computer engineering at the University of of the Raven II surgical California-Santa Cruz. Rosen and Blake Hannaford, director of the robotics systems. Credit: University of Washington Biorobotics Laboratory, led the team that Carolyn Lagattuta built the Raven system, initially with a U.S. -
Simultaneous Multiwavelength Flare Observations of Ev Lacertae
Draft version August 19, 2021 Typeset using LATEX twocolumn style in AASTeX61 SIMULTANEOUS MULTIWAVELENGTH FLARE OBSERVATIONS OF EV LACERTAE Rishi R. Paudel,1, 2 Thomas Barclay,1, 3 Joshua E. Schlieder,3 Elisa V. Quintana,3 Emily A. Gilbert,4, 5, 6, 3 Laura D. Vega,7, 3, 2 Allison Youngblood,8 Michele Silverstein,3 Rachel A. Osten,9 Michael A. Tucker,10, ∗ Daniel Huber,10 Aaron Do,10 Kenji Hamaguchi,11, 1 D. J. Mullan,12 John E. Gizis,12 Teresa A. Monsue,3 Knicole D. Colon,´ 3 Patricia T. Boyd,3 James R. A. Davenport,13 and Lucianne Walkowicz6 1University of Maryland, Baltimore County, Baltimore, MD 21250, USA 2CRESST II and Exoplanets and Stellar Astrophysics Laboratory, NASA/GSFC, Greenbelt, MD 20771, USA 3NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 4Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Ave, Chicago, IL 60637, USA 5University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA 6The Adler Planetarium, 1300 South Lakeshore Drive, Chicago, IL 60605, USA 7Department of Astronomy, University of Maryland, College Park, MD 20742, USA 8Laboratory for Atmospheric and Space Physics, 1234 Innovation Dr, Boulder, CO 80303, USA 9Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 10Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Drive, Honolulu, HI 96822, USA 11CRESST II and X-ray Astrophysics Laboratory NASA/GSFC, Greenbelt, MD, USA 12Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA 13Department of Astronomy, University of Washington, Seattle, WA 98195, USA ABSTRACT We present the first results of our ongoing project conducting simultaneous multiwavelength observations of flares on nearby active M dwarfs. -
Effect of the Solar Wind Density on the Evolution of Normal and Inverse Coronal Mass Ejections S
A&A 632, A89 (2019) Astronomy https://doi.org/10.1051/0004-6361/201935894 & c ESO 2019 Astrophysics Effect of the solar wind density on the evolution of normal and inverse coronal mass ejections S. Hosteaux, E. Chané, and S. Poedts Centre for mathematical Plasma-Astrophysics (CmPA), Celestijnenlaan 200B, KU Leuven, 3001 Leuven, Belgium e-mail: [email protected] Received 15 May 2019 / Accepted 11 September 2019 ABSTRACT Context. The evolution of magnetised coronal mass ejections (CMEs) and their interaction with the background solar wind leading to deflection, deformation, and erosion is still largely unclear as there is very little observational data available. Even so, this evolution is very important for the geo-effectiveness of CMEs. Aims. We investigate the evolution of both normal and inverse CMEs ejected at different initial velocities, and observe the effect of the background wind density and their magnetic polarity on their evolution up to 1 AU. Methods. We performed 2.5D (axisymmetric) simulations by solving the magnetohydrodynamic equations on a radially stretched grid, employing a block-based adaptive mesh refinement scheme based on a density threshold to achieve high resolution following the evolution of the magnetic clouds and the leading bow shocks. All the simulations discussed in the present paper were performed using the same initial grid and numerical methods. Results. The polarity of the internal magnetic field of the CME has a substantial effect on its propagation velocity and on its defor- mation and erosion during its evolution towards Earth. We quantified the effects of the polarity of the internal magnetic field of the CMEs and of the density of the background solar wind on the arrival times of the shock front and the magnetic cloud. -
Predicting the Magnetic Vectors Within Coronal Mass Ejections Arriving at Earth: 2
Space Weather RESEARCH ARTICLE Predicting the magnetic vectors within coronal mass ejections 10.1002/2015SW001171 arriving at Earth: 1. Initial architecture Key Points: N. P.Savani1,2, A. Vourlidas1, A. Szabo2,M.L.Mays2,3, I. G. Richardson2,4, B. J. Thompson2, • First architectural design to predict A. Pulkkinen2,R.Evans5, and T. Nieves-Chinchilla2,3 a CME’s magnetic vectors (with eight events) 1 2 • Modified Bothmer-Schwenn CME Goddard Planetary Heliophysics Institute (GPHI), University of Maryland, Baltimore County, Maryland, USA, NASA 3 initiation rule to improve reliability Goddard Space Flight Center, Greenbelt, Maryland, USA, Institute for Astrophysics and Computational Sciences (IACS), of chirality Catholic University of America, Washington, District of Columbia, USA, 4Department of Astronomy, University of • CME evolution seen by remote Maryland, College Park, Maryland, USA, 5College of Science, George Mason University, Fairfax, Vancouver, USA sensing triangulation is important for forecasting Abstract The process by which the Sun affects the terrestrial environment on short timescales is Correspondence to: predominately driven by the amount of magnetic reconnection between the solar wind and Earth’s N. P. Savani, magnetosphere. Reconnection occurs most efficiently when the solar wind magnetic field has a southward [email protected] component. The most severe impacts are during the arrival of a coronal mass ejection (CME) when the magnetosphere is both compressed and magnetically connected to the heliospheric environment. Citation: Unfortunately, forecasting magnetic vectors within coronal mass ejections remain elusive. Here we report Savani, N. P., A. Vourlidas, A. Szabo, M.L.Mays,I.G.Richardson,B.J. how, by combining a statistically robust helicity rule for a CME’s solar origin with a simplified flux rope Thompson, A. -
Arxiv:2101.07771V4 [Stat.AP] 9 Jun 2021
Received Jan-19-2021; Revised Jun-02-2021; Accepted XX-XX-XXX DOI: xxx/xxxx SURVEY Critical Risk Indicators (CRIs) for the electric power grid: A survey and discussion of interconnected effects Che-Castaldo, Judy P.*1 | Cousin, Rémi2 | Daryanto, Stefani3 | Deng, Grace4 | Feng, Mei-Ling E.1 | Gupta, Rajesh K.5 | Hong, Dezhi5 | McGranaghan, Ryan M.6 | Owolabi, Olukunle O.7 | Qu, Tianyi8 | Ren, Wei3 | Schafer, Toryn L. J.4 | Sharma, Ashutosh9,10 | Shen, Chaopeng9 | Sherman, Mila Getmansky8 | Sunter, Deborah A.7 | Tao, Bo3 | Wang, Lan11 | Matteson, David S.4 1Conservation & Science Department, Lincoln Park Zoo, Illinois, USA Abstract 2International Research Institute for Climate The electric power grid is a critical societal resource connecting multiple infrastruc- and Society, Earth Institute / Columbia University, New York, USA tural domains such as agriculture, transportation, and manufacturing. The electrical 3Department of Plant and Soil Sciences, grid as an infrastructure is shaped by human activity and public policy in terms of College of Agriculture, Food and Environment / University of Kentucky, demand and supply requirements. Further, the grid is subject to changes and stresses Kentucky, USA due to diverse factors including solar weather, climate, hydrology, and ecology. The 4 Department of Statistics and Data Science, emerging interconnected and complex network dependencies make such interactions Cornell University, New York, USA 5Halicioglu Data Science Institute and increasingly dynamic, posing novel risks, and presenting new challenges to manage Department of Computer Science & the coupled human-natural system. This paper provides a survey of models and meth- Engineering, University of California, San ods that seek to explore the significant interconnected impact of the electric power Diego, California, USA 6Atmosphere Space Technology Research grid and interdependent domains. -
X-Ray Properties of Active M Dwarfs As Observed by XMM-Newton
A&A 435, 1073–1085 (2005) Astronomy DOI: 10.1051/0004-6361:20041941 & c ESO 2005 Astrophysics X-ray properties of active M dwarfs as observed by XMM-Newton J. Robrade and J. H. M. M. Schmitt Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany e-mail: [email protected] Received 2 September 2004 / Accepted 8 February 2005 Abstract. We present a comparative study of X-ray emission from a sample of active M dwarfs with spectral types M3.5–M4.5 using XMM-Newton observations of two single stars, AD Leonis and EV Lacertae, and two unresolved binary systems, AT Microscopii and EQ Pegasi. The light curves reveal frequent flaring during all four observations. We perform a uniform spectral analysis and determine plasma temperatures, abundances and emission measures in different states of activity. Applying multi-temperature models with variable abundances separately to data obtained with the EPIC and RGS detectors we are able to investigate the consistency of the results obtained by the different instruments onboard XMM-Newton. We find that the X-ray properties of the sample M dwarfs are very similar, with the coronal abundances of all sample stars following a trend of increasing abundance with increasing first ionization potential, the inverse FIP effect. The overall metallicities are below solar photospheric ones but appear consistent with the measured photospheric abundances of M dwarfs like these. A significant increase in the prominence of the hotter plasma components is observed during flares while the cool plasma component is only marginally affected by flaring, pointing to different coronal structures. -
Publications Ofthe Astronomical Society Ofthe Pacific 99:490-496, June 1987
Publications ofthe Astronomical Society ofthe Pacific 99:490-496, June 1987 RADIAL VELOCITIES OF M DWARF STARS GEOFFREY W. MARCY,* VICTORIA LINDSAY,* AND KAREN WILSON Department of Physics and Astronomy, San Francisco State University, San Francisco, California 94132 Received 1987 February 26, revised 1987 March 28 ABSTRACT Radial velocities for 72 M dwarfs have been obtained having internal errors of about 0.1 km s1 and external errors of about 0.4 km s_1. Multiple velocity measurements of ten dMe stars have yielded a set of six which have no stellar companions, providing confirmation that the dMe phenomenon can occur in single stars. These single dMe stars have low space motions indicative of relative youth. Four stars from the entire survey were found to have double-line spectra and two were found to be single-line spectroscopic binaries of low amplitude. The zero point of the velocity scale is found to agree well with that of O. C. Wilson (1967) and differences are noted among other radial-velocity studies. Most of the stars in this study have velocities sufficiently well determined to constitute potential radial-velocity standards. Key words: K-M dwarfs-radial velocities I. Introduction atic difference between their velocities and O. C. 1 Accurate measurements of radial velocities for M Wilson's of —1.7 km s , a discrepancy not explainable by dwarfs are used to address a number of astrophysical the random errors of the two studies. problems such as the age dependence of the kinematics of Thus, it is not known at present which zero point is to the Galaxy (cf. -
HST/STIS Analysis of the First Main Sequence Pulsar CU Virginis
A&A 625, A34 (2019) Astronomy https://doi.org/10.1051/0004-6361/201834937 & © ESO 2019 Astrophysics HST/STIS analysis of the first main sequence pulsar CU Virginis?,?? J. Krtickaˇ 1, Z. Mikulášek1, G. W. Henry2, J. Janík1, O. Kochukhov3, A. Pigulski4, P. Leto5, C. Trigilio5, I. Krtickovᡠ1, T. Lüftinger6, M. Prvák1, and A. Tichý1 1 Department of Theoretical Physics and Astrophysics, Masaryk University, Kotlárskᡠ2, 611 37 Brno, Czech Republic e-mail: [email protected] 2 Center of Excellence in Information Systems, Tennessee State University, Nashville, TN, USA 3 Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden 4 Astronomical Institute, Wrocław University, Kopernika 11, 51-622 Wrocław, Poland 5 INAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy 6 Institut für Astronomie, Universität Wien, Türkenschanzstraße 17, 1180 Wien, Austria Received 20 December 2018 / Accepted 5 March 2019 ABSTRACT Context. CU Vir has been the first main sequence star that showed regular radio pulses that persist for decades, resembling the radio lighthouse of pulsars and interpreted as auroral radio emission similar to that found in planets. The star belongs to a rare group of magnetic chemically peculiar stars with variable rotational period. Aims. We study the ultraviolet (UV) spectrum of CU Vir obtained using STIS spectrograph onboard the Hubble Space Telescope (HST) to search for the source of radio emission and to test the model of the rotational period evolution. Methods. We used our own far-UV and visual photometric observations supplemented with the archival data to improve the parameters of the quasisinusoidal long-term variations of the rotational period. -
Radio Spectroscopy of Stellar Flares: Magnetic Reconnection & CME
Solar and Stellar Flares and their Effects on Planets Proceedings IAU Symposium No. 320, 2015 c International Astronomical Union 2016 A.G. Kosovichev, S.L. Hawley & P. Heinzel, eds. doi:10.1017/S1743921316008644 Radio spectroscopy of stellar flares: magnetic reconnection & CME shocks in stellar coronae Jackie Villadsen1, Gregg Hallinan1 and Stephen Bourke1 1 Department of Astronomy, California Institute of Technology MC 249-17, 1200 E California Blvd, Pasadena, CA 91125, USA email: [email protected], [email protected], [email protected] Abstract. High-cadence spectroscopy of solar and stellar coherent radio bursts is a powerful diagnostic tool to study coronal conditions during magnetic reconnection in flares and to detect coronal mass ejections (CMEs). We present results from wide-bandwidth VLA observations of nearby active M dwarfs, including some observations with simultaneous VLBA imaging. We also discuss the Starburst program, which will make wide-bandwidth radio spectroscopic observations of nearby active flare stars for 20+ hours a day for multiple years, coming online in spring 2016 at the Owens Valley Radio Observatory. This program should vastly increase the diversity of observed stellar radio bursts and our understanding of their origins, and offers the potential to detect a population of CME-associated radio bursts. Keywords. stars: coronae, stars: flare, stars: individual (UV Ceti), stars: mass loss, Sun: coronal mass ejections (CMEs), Sun: radio radiation, radio continuum: stars 1. Introduction Many of the nearest habitable-zone Earths and super-Earths will be found around M dwarfs (Dressing & Charbonneau 2013). The magnetically active “youth” of M dwarfs lasts hundreds of millions to billions of years (West et al. -
The Radio Astronomy of Bruce Slee
CSIRO PUBLISHING Review www.publish.csiro.au/journals/pasa Publications of the Astronomical Society of Australia, 2004, 21, 23–71 From the Solar Corona to Clusters of Galaxies: The Radio Astronomy of Bruce Slee Wayne Orchiston Australia Telescope National Facility, PO Box 76, Epping NSW 2121, Australia (e-mail: [email protected]) Received 2003 May 8, accepted 2003 September 27 Abstract: Owen Bruce Slee is one of the pioneers of Australian radio astronomy. During World War II he independently discovered solar radio emission, and, after joining the CSIRO Division of Radiophysics, used a succession of increasingly more sophisticated radio telescopes to examine an amazing variety of celestial objects and phenomena. These ranged from the solar corona and other targets in our solar system, to different types of stars and the ISM in our Galaxy, and beyond to distant galaxies and clusters of galaxies. Although long retired, Slee continues to carry out research, with emphasis on active stars and clusters of galaxies. A quiet and unassuming man, Slee has spent more than half a century making an important, wide-ranging contribution to astronomy, and his work deserves to be more widely known. Keywords: biographies — Bruce Slee — radio continuum: galaxies — radio continuum: ISM — radio continuum: stars — stars: flare — Sun: corona 1 Introduction Radio astronomy is so new a discipline that it has yet to acquire an extensive historical bibliography. With founda- tions dating from 1931 this is perhaps not surprising, and it is only since the publication of Sullivan’s classic work, The Early Years of Radio Astronomy, in 1984 that schol- ars have begun to take a serious interest in the history of this discipline and its ‘key players’. -