Search

Your search keyword '"Alcock, Charles"' showing total 110 results
Start Over Author "Alcock, Charles" Publication Type Magazines
110 results on '"Alcock, Charles"'

1. The performance of the Mosaic CMOS Wide Field Camera for Transneptunian Automatic Occultation Survey (TAOS II)

Author

Bryant, Julia J., Motohara, Kentaro, Vernet, Joël R. D., Wang, Shiang-Yu, Wang, Bo-Jhou, Huang, Chung-Kai, Ling, Hung-Hsu, Chang, Yin-Chang, Hsu, Shu-Fu, Chen, Hsin-Yo, Zhang, Zhi-Wei, Lehner, Matthew, Geary, John C., Amato, Stephen M., Szentgyorgyi, Andrew, Norton, Timothy, Alcock, Charles, Castro-Chacón, Joel, and Reyes-Ruíz, Mauricio

Published
2024
Full Text
View/download PDF

23. Letters.

Author

STOCKDALE II, JAMES B., VARRO, JOSEPH, SHERMAN, PHILIP S., EYMAN, WILLIAM R., TURNER, WILL, MILLER, DAVID, BOWEN, DAN, DIEBOLD, WILLIAM, HUTCHESON, ROBERT W., GASCH, RODNEY J., WAEGEL, NANCY, BISSELL, LOLITA H., GALVIN, RUTH MEHRTENS, ALCOCK, CHARLES, HOOVER, EDGAR, BROWN JR., JAMES W., WALKER, SIMON, WINGER, PRISCILLA H., KLEMPERER, GEORGE F., and THORPE, PETER

Subjects
LETTERS to the editor, PRISONERS of war, IMMIGRANTS, POLLUTION
Abstract

Several letters to the editor are presented in response to articles in previous issues including the article on American prisoners of war in the December 7, 1970 issue, on American emigrants in the November 30, 1970 issue, and on environmental pollution in Soviet Union in the November 30, 1970 issue.

Published
1970

24. Status of the Transneptunian Automated Occultation Survey (TAOS II)

Author

Marshall, Heather K., Spyromilio, Jason, Lehner, Matthew J., Wang, Shiang-Yu, Reyes-Ruíz, Mauricio, Zhang, Zhi-Wei, Figueroa, Liliana, Huang, Chung-Kai, Yen, Wei-Ling, Alcock, Charles, Alvarez Santana, Fernando, Castro-Chacón, Joel, Chen, Wen-Ping, Chu, You-Hua, Cook, Kem H., Geary, John C., Hernández, Benjamín, Karr, Jennifer E., Kavelaars, J. J., Norton, Timothy, and Szentgyorgyi, Andrew

Published
2018
Full Text
View/download PDF

25. The Telescopio San Pedro Mártir project

Author

Marshall, Heather K., Spyromilio, Jason, Richer, Michael G., Lee, William H., Altamirano, Leopoldo, González, J. Jesús, Alcock, Charles, Jannuzi, Buell, Rosales-Ortega, Fabián, García-Vargas, Marisa, Herrera Vázquez, Joel, Hill, Derek, Pedrayes, María Herlinda, Pérez Calpena, Ana, Reyes Ruiz, Mauricio, Rodríguez Merino, Lino Hector, Sánchez, Beatriz, Serrano Guerrero, Hazael, Sierra Díaz, Gerardo, Szentgyorgyi, Andrew, Teran, Jose, Urdaibay, David, Uribe Uribe, Jorge Andrés, Watson, Alan M., Zaritsky, Dennis, Rascon, Mario, Ceseña Borbón, Urania, Bracamontes, Francisco Murillo, Parra, Fernando Quirós, and Sohn, Erika

Published
2018
Full Text
View/download PDF

33. The Telescopio San Pedro Mártir project

Author

Hall, Helen J., Gilmozzi, Roberto, Marshall, Heather K., Richer, Michael G., Lee, William H., González, Jesús, Jannuzi, Buell T., Sánchez, Beatriz, Rosales Ortega, Fabián, Alcock, Charles, Carramiñana Alonso, Alberto, García Díaz, Ma. Teresa, Gutiérrez, Leonel, Herrera, Joel, Hill, Derek, Norton, Timothy J., Pedrayes, Maria H., Pérez-Calpena, Ana, Reyes-Ruíz, Mauricio, Serrano Guerrero, Hazael, Sierra, Gerardo, Teran, Jose, Urdaibay, David, Uribe, Jorge A., Watson, Alan M., Zaritsky, Dennis, and García Vargas, Marisa

Published
2016
Full Text
View/download PDF

34. Status of the Transneptunian Automated Occultation Survey (TAOS II)

Author

Hall, Helen J., Gilmozzi, Roberto, Marshall, Heather K., Lehner, Matthew J., Wang, Shiang-Yu, Reyes-Ruiz, Mauricio, Alcock, Charles, Castro, Joel, Chen, Wen-Ping, Chu, You-Hua, Cook, Kem H., Figueroa, Liliana, Geary, John C., Huang, Chung-Kai, Kim, Dae-Won, Norton, Timothy, Szentgyorgyi, Andrew, Yen, Wei-Ling, and Zhang, Zhi-Wei

Published
2016
Full Text
View/download PDF

35. Repetitive patterns in rapid optical variations in the nearby black-hole binary V404 Cygni

Author

Kimura, Mariko, Isogai, Keisuke, Kato, Taichi, Ueda, Yoshihiro, Nakahira, Satoshi, Shidatsu, Megumi, Enoto, Teruaki, Hori, Takafumi, Nogami, Daisaku, Littlefield, Colin, Ishioka, Ryoko, Chen, Ying-Tung, King, Sun-Kun, Wen, Chih-Yi, Wang, Shiang-Yu, Lehner, Matthew J., Schwamb, Megan E., Wang, Jen-Hung, Zhang, Zhi-Wei, Alcock, Charles, Axelrod, Tim, Bianco, Federica B., Byun, Yong-Ik, Chen, Wen-Ping, Cook, Kem H., Kim, Dae-Won, Lee, Typhoon, Marshall, Stuart L., Pavlenko, Elena P., Antonyuk, Oksana I., Antonyuk, Kirill A., Pit, Nikolai V., Sosnovskij, Aleksei A., Babina, Julia V., Baklanov, Aleksei V., Pozanenko, Alexei S., Mazaeva, Elena D., Schmalz, Sergei E., Reva, Inna V., Belan, Sergei P., Inasaridze, Raguli Ya., Tungalag, Namkhai, Volnova, Alina A., Molotov, Igor E., Miguel, Enrique de, Kasai, Kiyoshi, Stein, William L., Dubovsky, Pavol A., Kiyota, Seiichiro, Miller, Ian, Richmond, Michael, Goff, William, Andreev, Maksim V., Takahashi, Hiromitsu, Kojiguchi, Naoto, Sugiura, Yuki, Takeda, Nao, Yamada, Eiji, Matsumoto, Katsura, James, Nick, Pickard, Roger D., Tordai, Tamás, Maeda, Yutaka, Ruiz, Javier, Miyashita, Atsushi, Cook, Lewis M., Imada, Akira, and Uemura, Makoto

Abstract

How black holes accrete surrounding matter is a fundamental yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion disks, the state of which depends primarily on the mass-accretion rate. When this rate approaches the critical rate (the Eddington limit), thermal instability is supposed to occur in the inner disk, causing repetitive patterns of large-amplitude X-ray variability (oscillations) on timescales of minutes to hours. In fact, such oscillations have been observed only in sources with a high mass-accretion rate, such as GRS 1915+105 (refs 2, 3). These large-amplitude, relatively slow timescale, phenomena are thought to have physical origins distinct from those of X-ray or optical variations with small amplitudes and fast timescales (less than about 10 seconds) often observed in other black-hole binaries—for example, XTE J1118+480 (ref. 4) and GX 339−4 (ref. 5). Here we report an extensive multi-colour optical photometric data set of V404 Cygni, an X-ray transient source containing a black hole of nine solar masses (and a companion star) at a distance of 2.4 kiloparsecs (ref. 8). Our data show that optical oscillations on timescales of 100 seconds to 2.5 hours can occur at mass-accretion rates more than ten times lower than previously thought. This suggests that the accretion rate is not the critical parameter for inducing inner-disk instabilities. Instead, we propose that a long orbital period is a key condition for these large-amplitude oscillations, because the outer part of the large disk in binaries with long orbital periods will have surface densities too low to maintain sustained mass accretion to the inner part of the disk. The lack of sustained accretion—not the actual rate—would then be the critical factor causing large-amplitude oscillations in long-period systems.

Published
2016
Full Text
View/download PDF

47. A BAYESIAN APPROACH TO THE ANALYSIS OF TIME SYMMETRY IN LIGHT CURVES: RECONSIDERING SCORPIUS X-1 OCCULTATIONS

Author

Blocker, Alexander W., Protopapas, Pavlos, and Alcock, Charles R.

Abstract

We present a new approach to the analysis of time symmetry in light curves, such as those in the X-ray at the center of the Scorpius X-1 occultation debate. Our method uses a new parameterization for such events (the bilogistic event profile) and provides a clear, physically relevant characterization of each event's key features. We also demonstrate a Markov chain Monte Carlo algorithm to carry out this analysis, including a novel independence chain configuration for the estimation of each event's location in the light curve. These tools are applied to the Scorpius X-1 light curves presented in Chang et al., providing additional evidence based on the time series that the events detected thus far are most likely not occultations by trans-Neptunian objects.

Published
2009

48. REVISITING THE ROLE OF M31 IN THE DYNAMICAL HISTORY OF THE MAGELLANIC CLOUDS

Author

Kallivayalil, Nitya, Besla, Gurtina, Sanderson, Robyn, and Alcock, Charles

Abstract

We study the dynamics of the Magellanic Clouds in a model for the Local Group whose mass is constrained using the timing argument/two-body limit of the action principle. The goal is to evaluate the role of M31 in generating the high angular momentum orbit of the Clouds, a puzzle that has only been exacerbated by the latest Hubble Space Telescope proper motion measurements. We study the effects of varying the total Local Group mass, the relative mass of the Milky Way (MW) and M31, the proper motion of M31, and the proper motion of the Large Magellanic Cloud (LMC) on this problem. Over a large part of this parameter space, we find that tides from M31 are insignificant. For a range of LMC proper motions approximately 3s higher than the mean and total Local Group mass >3.5 x 1012 M , M31 can provide a significant torque to the LMC orbit. However, if the LMC is bound to the MW, then M31 is found to have negligible effect on its motion, and the origin of the high angular momentum of the system remains a puzzle. Finally, we use the timing argument to calculate the total mass of the MW-LMC system based on the assumption that they are encountering each other for the first time, their previous perigalacticon being a Hubble time ago, obtaining M MW + M LMC = (8.7 +- 0.8) x 1011 M .

Published
2009

Catalog

Books, media, physical & digital resources
See catalog results