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Artykuły w czasopismach na temat „Accretion phenomena”

Autor: Grafiati

Data publikacji: 8 czerwca 2024

Data aktualizacji: 31 lipca 2025

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1

Bailey, Jeremy. "Accretion Phenomena in Cataclysmic Variables." Publications of the Astronomical Society of Australia 13, no. 1 (1996): 75–80. http://dx.doi.org/10.1017/s1323358000020579.

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AbstractThe processes of accretion onto the white dwarf in a cataclysmic variable are reviewed. These systems provide the most easily observable examples of accretion disks, and enable the structure of the accretion region to be studied in detail. The properties of column accretion onto magnetic cataclysmic variables are also described.

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2

Walker, Mark. "Accretion-driven nonthermal phenomena." Astrophysical Journal 330 (July 1988): L47. http://dx.doi.org/10.1086/185202.

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KUNCIC, ZDENKA, and GEOFFREY V. BICKNELL. "TOWARDS A NEW STANDARD THEORY FOR ASTROPHYSICAL DISK ACCRETION." Modern Physics Letters A 22, no. 23 (2007): 1685–700. http://dx.doi.org/10.1142/s0217732307024243.

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We briefly review recent developments in black hole accretion disk theory, placing new emphasis on the vital role played by magnetohydrodynamic (MHD) stresses in transporting angular momentum. The apparent universality of accretion-related outflow phenomena is a strong indicator that vertical transport of angular momentum by large-scale MHD torques is important and may even dominate radial transport by small-scale MHD turbulence. This leads to an enhanced overall rate of angular momentum transport and allows accretion of matter to proceed at an interesting rate. Furthermore, we argue that when

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4

Lee, Umin, and Tod E. Strohmayer. "Thermonuclear Excitation of R-modes in Neutron Stars." International Astronomical Union Colloquium 155 (1995): 445–46. http://dx.doi.org/10.1017/s0252921100037921.

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AbstractNeutron stars display phenomena which result from the burning of accreted nuclear fuel in their surface layers. In addition to producing X-ray bursts and other temporal phenomema, such burning can excite oscillation modes of the neutron star. Here we investigate the stability of R-modes in uniformly rotating neutron stars using nonadiabatic pulsation calculations of steady burning envelopes on accreting neutron stars. We find that the fundamental R-modes are unstable for a large range of accretion rates, and thus might manifest themselves observationally in the power spectra of accreti

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5

Kim, Hongsu, and Uicheol Jang. "Effect of Radiation Pressure Formed at the Inner Region of the Accretion Disk on the Accretion Flow in the Outer Region." Journal of Astronomy and Space Sciences 40, no. 4 (2023): 247–58. http://dx.doi.org/10.5140/jass.2023.40.4.247.

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Studying the accretion phenomena provides a window into understanding most heavenly bodies, from the birth of stars to active galactic nuclei (AGN). We would adopt the effect of the radiation pressure, which reduces accretion rates ( M ˙ ), on the accretion phenomena. The Shakura-Sunyaev α-disk model of disk accretion is a good candidate theory of advection dominated accretion flow (ADAF). Reduction in the angular velocity leads to the suppression the disk luminosity and surface temperature, essentially indicating the transition of the standard accretion disk model from convection dominated ac

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6

Yokosawa, M. "Dynamical Evolution of Accretion Flow onto a Black Hole." Symposium - International Astronomical Union 188 (1998): 455–56. http://dx.doi.org/10.1017/s0074180900116006.

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Active galactic nuclei(AGN) produce many type of active phenomena, powerful X-ray emission, UV hump, narrow beam ejection, gamma-ray emission. Energy of these phenomena is thought to be brought out binding energy between a black hole and surrounding matter. What condition around a black hole produces many type of active phenomena? We investigated dynamical evolution of accretion flow onto a black hole by using a general-relativistic, hydrodynamic code which contains a viscosity based on the alpha-model. We find three types of flow's pattern, depending on thickness of accretion disk. In a case

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7

Ferreira, J. "Accretion-ejection phenomena from young stars." EAS Publications Series 9 (2003): 33. http://dx.doi.org/10.1051/eas:2003083.

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8

Tanaka, Y. "Outburst Phenomena in X-Ray Binaries." Symposium - International Astronomical Union 151 (1992): 215–24. http://dx.doi.org/10.1017/s0074180900122211.

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Three distinctly different types of outburst phenomenon in X-ray binaries are discussed: (1) the so-called type 1 burst which is a thermonuclear flash of matter accreted on the surface of neutron stars, (2) the so-called type 2 burst which is a burst-like X-ray emission caused by a spasmodic accretion, and (3) the nova-like outburst which is triggered by a sudden commencement of accretion.

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9

Iijima, T. "Rapid Mass Accretion in the Symbiotic Star AG Dra." International Astronomical Union Colloquium 93 (1987): 759–62. http://dx.doi.org/10.1017/s0252921100105640.

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AbstractThe mass accretion process onto the hot component of AG Dra and its explosive phenomena are discussed. The hot component seems to be a massive white dwarf (M > 1 M⊙). The mass accretion rate is estimated to be about 10−7M⊙/year. Many properties of the explosive phenomena agree with those of mild hydrogen flashes expected from this rapid mass accretion.

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10

de Gouveia Dal Pino, Elisabete M., and Alex C. Raga. "JD7 -Astrophysical Outflows and Associated Accretion Phenomena." Proceedings of the International Astronomical Union 5, H15 (2009): 235–36. http://dx.doi.org/10.1017/s1743921310009002.

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Highly collimated supersonic jets and outflows are very frequent in several astrophysical environments. They are seen in young stellar objects (YSOs), proto-planetary nebulae, compact objects (like galactic black holes or microquasars, and X-ray binary stars), active galactic nuclei, and are also possibly associated to gamma-ray bursts (GRBs) and to ultra-high energy cosmic rays sources (UHECRs). Despite their different physical scales, all these outflow classes have strong morphological similarities, but questions such as - what physics do they share? - or - can we find a universal mechanism

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11

Baan, Willem A., Hiroshi Imai, and Gabor Orosz. "Fallback in bipolar planetary nebulae?" Research in Astronomy and Astrophysics 21, no. 11 (2021): 275. http://dx.doi.org/10.1088/1674-4527/21/11/275.

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Abstract The subclass of bipolar Planetary Nebulae (PNe) exhibits well-defined low-power outflows and some shows shock-related equatorial spiderweb structures and hourglass structures surrounding these outflows. These structures are distinctly different from the phenomena associated with spherical and elliptical PNe and suggest a non-standard way to simultaneously energise both kinds of structures. This paper presents evidence from the published literature on bipolar PN Hb 12 and other sources in support of an alternative scenario for energising these structures by means of accretion from mate

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12

Schneider, P. Christian, H. Moritz Günther, and Kevin France. "The UV Perspective of Low-Mass Star Formation." Galaxies 8, no. 1 (2020): 27. http://dx.doi.org/10.3390/galaxies8010027.

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The formation of low-mass ( M ★ ≲ 2 M ⊙ ) stars in molecular clouds involves accretion disks and jets, which are of broad astrophysical interest. Accreting stars represent the closest examples of these phenomena. Star and planet formation are also intimately connected, setting the starting point for planetary systems like our own. The ultraviolet (UV) spectral range is particularly suited for studying star formation, because virtually all relevant processes radiate at temperatures associated with UV emission processes or have strong observational signatures in the UV range. In this review, we

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13

Simon, Jacob B., Kris Beckwith, and Philip J. Armitage. "Emergent mesoscale phenomena in magnetized accretion disc turbulence." Monthly Notices of the Royal Astronomical Society 422, no. 3 (2012): 2685–700. http://dx.doi.org/10.1111/j.1365-2966.2012.20835.x.

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14

Annibali, F., M. Tosi, A. Aloisi, et al. "Accretion phenomena in nearby star-forming dwarf galaxies." Proceedings of the International Astronomical Union 11, S321 (2016): 211–13. http://dx.doi.org/10.1017/s1743921316009017.

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AbstractWe present two pilot studies for the search and characterization of accretion events in star-forming dwarf galaxies. Our strategy consists of two complementary approaches: i) the direct search for stellar substructures around dwarf galaxies through deep wide-field imaging, and ii) the characterization of the chemical properties in these systems up to large galacto-centric distances. We show our results for two star-forming dwarf galaxies, the starburst irregular NGC 4449, and the extremely metal-poor dwarf DDO 68.

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15

Bu, De-Fu, and Feng Yuan. "Outflows from black hole accretion flows with various accretion rates." Proceedings of the International Astronomical Union 19, S378 (2023): 104–7. http://dx.doi.org/10.1017/s1743921323003241.

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AbstractBoth observations and theoretical studies have convincingly shown that outflows (i.e., wind and jet) are common phenomena from black hole accretion systems with various accretion rates, although the physical driving mechanisms are not exactly same for different accretion modes. Outflows are not only important in the dynamics of black hole accretion, but also play an important role in AGN feedback; therefore it is crucial to investigate their main physical properties including mass flux and velocity. In this paper we summarize recent studies in investigating the properties and driving m

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16

Leonov, I. I., and N. N. Sokolikhina. "Severe hard rime accretion in the Far North of Russia: observations and modeling." IOP Conference Series: Earth and Environmental Science 1023, no. 1 (2022): 012012. http://dx.doi.org/10.1088/1755-1315/1023/1/012012.

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Abstract Severe weather means any hazardous meteorological phenomena which can cause significant damage, serious social disruption, or loss of human life. Such weather phenomena include thunderstorms, hurricanes, tornados, ice storms, and many others. The main purpose of this research is a study of formation mechanisms of rime accretion and methods for their prediction. This is necessary to forecast these phenomena and minimize their economic and other losses. This work is dedicated to a detailed study of an extraordinary case of formation of rime accretion in the territory of the Yamalo-Nenet

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17

King, A. R. "Accretion Disc Instabilities." Symposium - International Astronomical Union 151 (1992): 195–203. http://dx.doi.org/10.1017/s0074180900122193.

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I give a brief discussion of accretion disc instabilities, concentrating mainly on tidal instabilities caused by the presence of a binary companion. The superhumps observed in superoutbursts of SU UMa dwarf novae probably result from the excitation of a resonance in the accretion disc near the 3:1 commensurability with the binary orbit. This resonance can only appear for mass ratios q = M2/M1 < qerit ≃ 0.25 – 0.33: for larger mass ratios the available resonances are considerably weaker. Application of this picture to other types of binary suggests that the condition q < qerit may be nece

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18

Court, J. M. C., S. Scaringi, C. Littlefield, et al. "EX draconis: using eclipses to separate outside-in and inside-out outbursts." Monthly Notices of the Royal Astronomical Society 494, no. 4 (2020): 4656–64. http://dx.doi.org/10.1093/mnras/staa1042.

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ABSTRACT We present a study of the eclipses in the accreting white dwarf EX draconis (EX Dra) during TESS Cycles 14 and 15. During both of the two outbursts present in this data set, the eclipses undergo a hysteretic loop in eclipse-depth/out-of-eclipse-flux space. In each case, the direction in which the loops are executed strongly suggests an outburst that is triggered near the inner edge of the accretion disc and propagates outwards. This in turn suggests that the outbursts in EX Dra are ‘inside out’ outbursts; events predicted by previous hydrodynamic studies of dwarf nova accretion discs

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19

Stuchlík, Zdeněk, and Jan Schee. "Observational phenomena in the field of Kerr Superspinars." Proceedings of the International Astronomical Union 8, S290 (2012): 313–14. http://dx.doi.org/10.1017/s1743921312020170.

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AbstractWe test observational consequences of primordial Kerr superspinars indicated by string theories. We demonstrate that Kerr superspinars can serve as ultra-high energy accelerators and explore specific optical phenomena related to accretion discs orbiting them.

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20

Hawley, J. F. "Numerical Simulations of MHD Accretion Disks." Proceedings of the International Astronomical Union 5, H15 (2009): 237–38. http://dx.doi.org/10.1017/s1743921310009014.

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AbstractNumerical simulations play an increasingly important role in investigating accretion disks and associated phenomena such as jets. This paper provides a few examples of recent results that have been obtained with simulations, both local or global.

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21

Buckley, D. A. H., S. B. Potter, E. Kotze, M. Kotze, and H. Breytenbach. "New Observations of Accretion Phenomena in Magnetic Cataclysmic Variables." EPJ Web of Conferences 64 (2014): 07005. http://dx.doi.org/10.1051/epjconf/20136407005.

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22

Mohanty, Subhanjoy. "Star-disk interaction in brown dwarfs: implications for substellar formation." Proceedings of the International Astronomical Union 3, S243 (2007): 345–56. http://dx.doi.org/10.1017/s1743921307009702.

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AbstractI review the current state of knowledge regarding disk accretion in young brown dwarfs (BDs), and the interaction of the disk with the central object. In particular, I discuss (1) observations of accretion/outflow phenomena in BDs; (2) techniques for measuring accretion rates (Ṁacc); (3) the dependence of Ṁacc on the central mass from stars to brown dwarfs; (4) the temporal evolution of Ṁacc; and (5) observations of variability in the accretion line profiles. I then examine the implications of these issues for the formation mechanism of BDs, and discuss new observations that can furthe

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23

Migliori, Giulia, R. Margutti, B. D. Metzger, et al. "Roaring to Softly Whispering: X-Ray Emission after ∼3.7 yr at the Location of the Transient AT2018cow and Implications for Accretion-powered Scenarios*." Astrophysical Journal Letters 963, no. 1 (2024): L24. http://dx.doi.org/10.3847/2041-8213/ad2764.

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Abstract We present the first deep X-ray observations of luminous fast blue optical transient (LFBOT) AT 2018cow at ∼3.7 yr since discovery, together with the reanalysis of the observation at δ t ∼ 220 days. X-ray emission is significantly detected at a location consistent with AT 2018cow. The very soft X-ray spectrum and sustained luminosity are distinct from the spectral and temporal behavior of the LFBOT in the first ∼100 days and would possibly signal the emergence of a new emission component, although a robust association with AT 2018cow can only be claimed at δ t ∼ 220 days, while at δ t

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24

Weng, Shan-Shan, and Long Ji. "X-Ray Views of Galactic Accreting Pulsars in High-Mass X-Ray Binaries." Universe 10, no. 12 (2024): 453. https://doi.org/10.3390/universe10120453.

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Accreting X-ray pulsars, located in X-ray binaries, are neutron stars with magnetic fields as strong as B∼1012–13 G. This review offers a concise overview of the accretion and radiation processes of X-ray pulsars and summarizes their rich observational features, particularly focusing on complex and variable temporal phenomena, spectral properties, and evolution, the new window for X-ray polarimetry and multi-wavelength advances. We also briefly discuss other related systems, i.e., gamma-ray binaries and pulsating ultraluminous X-ray sources.

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25

Wang, De-Hua, and Cheng-Min Zhang. "The parallel tracks of kHz QPOs in low-mass X-ray binary 4U 1728−34: explorer of the bimodal accretion modes." Monthly Notices of the Royal Astronomical Society 497, no. 3 (2020): 2893–98. http://dx.doi.org/10.1093/mnras/staa2161.

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ABSTRACT Parallel tracks in the relation between the lower kilohertz quasi-periodic oscillation (kHz QPO) frequency ν1 and the X-ray intensity I have been observed in the neutron star low-mass X-ray binary (NS-LMXB) 4U 1728−34, and we try to ascribe these phenomena to the bimodal accretion modes, i.e. the disc accretion and radial accretion. For the source with one constant radial accretion rate $\dot{M}_{\rm r}$, as the increase of the disc accretion rate $\dot{M}_{\rm d}$, the NS magnetosphere-disc radius can shrink from ∼18 to ∼16 km, while ν1 increases from ∼670 to ∼870 Hz. Then, due to th

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Bandyopadhyay, Tanwi, and Ujjal Debnath. "Accretions of Tsallis, Rényi and Sharma–Mittal dark energies onto higher-dimensional Schwarzschild black hole and Morris–Thorne wormhole." Modern Physics Letters A 36, no. 12 (2021): 2150081. http://dx.doi.org/10.1142/s0217732321500814.

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In this work, we study the dark energy accretion phenomena onto [Formula: see text]-dimensional Schwarzschild black hole and [Formula: see text]-dimensional Morris–Thorne wormhole. We obtain the [Formula: see text]-dimensional Schwarzschild black hole mass and [Formula: see text]-dimensional Morris–Thorne wormhole mass and their rate of change of masses due to accretion. For the dark energy component, we consider Tsallis, modified Rényi and “modified” Sharma–Mittal holographic dark energy (HDE) and new agegraphic dark energy (NADE). We also find the black hole mass and the wormhole mass in ter

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27

Liska, M. T. P., N. Kaaz, G. Musoke, A. Tchekhovskoy, and O. Porth. "Radiation Transport Two-temperature GRMHD Simulations of Warped Accretion Disks." Astrophysical Journal Letters 944, no. 2 (2023): L48. http://dx.doi.org/10.3847/2041-8213/acb6f4.

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Abstract In many black hole (BH) systems, the accretion disk is expected to be misaligned with respect to the BH spin axis. If the scale height of the disk is much smaller than the misalignment angle, the spin of the BH can tear the disk into multiple, independently precessing “sub-disks.” This is most likely to happen during outbursts in black hole X-Ray binaries (BHXRBs) and in active galactic nuclei (AGNs) accreting above a few percent of the Eddington limit, because the disk becomes razor-thin. Disk tearing has the potential to explain variability phenomena including quasi-periodic oscilla

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Czerny, B. "Emission of Accretion Disks." Symposium - International Astronomical Union 159 (1994): 261–70. http://dx.doi.org/10.1017/s0074180900175138.

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Accretion disks surrounding massive black hole is an attractive scenario of nuclear activity. A number of arguments support it although there is no unquestionable proof of the existence of accretion disks in active galactic nuclei. Meaningful comparison of the disk model prediction with the data can only be made if emission of accretion disks is calculated taking into account the existence of optically thin parts responsible for the emission of x-ray radiation. Nonlocal reprocessing phenomena have to be also included. Since we have no real understanding of the viscous processes operating in ac

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Tajima, Y., and J. Fukue. "Electron-Positron Pair Winds from Central Luminous Accretion Disk with Radiation Drag." Symposium - International Astronomical Union 188 (1998): 402–3. http://dx.doi.org/10.1017/s0074180900115736.

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The accretion disks are now supposed to be the main driving source of the active astrophysical phenomena. Even the electron-positron pair plasma will be created at the surface of the sufficiently luminous disk. While the effect of radiation drag which causes in the intense radiation fields around the accretion disk is examined recently. Then, we numerically consider the radiative accelerated pair-winds, which blow off from central luminous accretion disk surrounding a black hole, taking into account radiation drag of the order of v/c.

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Dittmann, Alexander J., and Matteo Cantiello. "A Semi-analytical Model for Stellar Evolution in AGN Disks." Astrophysical Journal 979, no. 2 (2025): 245. https://doi.org/10.3847/1538-4357/ad9e92.

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Abstract Disks of gas accreting onto supermassive black holes may host numerous stellar-mass objects, formed within the disk or captured from a nuclear star cluster. We present a simplified model of stellar evolution in these dense environments, which exhibits exceptional agreement with full stellar evolution calculations at a minuscule fraction of the cost. Although the model presented here is limited to stars burning hydrogen in their cores, it is sufficient to determine the evolutionary fate of disk-embedded stars: whether they proceed to later stages of nuclear burning and leave behind a c

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Okuda, T., V. Teresi, and D. Molteni. "QPOs expected in rotating accretion flows around a supermassive black hole." Proceedings of the International Astronomical Union 2, S238 (2006): 423–24. http://dx.doi.org/10.1017/s1743921307005765.

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AbstractIt is well known that rotating inviscid accretion flows with adequate injection parameters around black holes could form shock waves close to the black holes, after the flow passes through the outer sonic point and can be virtually stopped by the centrifugal force. We numerically examine such shock waves in 2D accretion flows with 10−5 to 106 Eddington critical accretion rates around a supermassive black hole with 106M⊙. As the results, the luminosities show QPO phenomena with modulations of a factor 2–3 and with quasi-periods of a few to several hours.

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MUKHOPADHYAY, BANIBRATA. "HYDRODYNAMICAL STUDY OF ADVECTIVE ACCRETION FLOW AROUND NEUTRON STARS." International Journal of Modern Physics D 11, no. 08 (2002): 1305–19. http://dx.doi.org/10.1142/s0218271802002244.

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Here we study the accretion process around neutron stars, especially for the cases where shock does form in the accretion disk. In case of accretion flows around a black hole, close to the horizon the matter is supersonic. On the other hand for the case of neutron stars and white dwarfs, matter must be subsonic close to the inner boundary. So the nature of the inflowing matter around neutron stars and white dwarfs are strictly different from that around black holes in the inner region of the disk. Here we discuss a few phenomena and the corresponding solutions of hydrodynamic equations of matt

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Burdonov, K., W. Yao, A. Sladkov, et al. "Laboratory modelling of equatorial ‘tongue’ accretion channels in young stellar objects caused by the Rayleigh-Taylor instability." Astronomy & Astrophysics 657 (January 2022): A112. http://dx.doi.org/10.1051/0004-6361/202140997.

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Context. The equatorial accretion scenario, caused by the development of the Rayleigh-Taylor (RT) instability at the disk edge, was suggested by accurate three-dimensional magnetohydrodynamic (MHD) modelling, but no observational or experimental confirmation of such phenomena has been evidenced yet. Aims. We studied the propagation of a laterally extended laser-generated plasma stream across a magnetic field and investigated if this kind of structure can be scaled to the case of equatorial ‘tongue’ accretion channels in young stellar objects (YSOs); if so, this would support the possibility of

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Durjasz, Michał. "Catching unusual phenomena with extensive maser monitoring." Proceedings of the International Astronomical Union 18, S380 (2022): 210–12. http://dx.doi.org/10.1017/s1743921323002260.

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AbstractHigh brightness and low interstellar extinction allow the 6.7 GHz methanol (CH3OH) masers to carry the information about what happens in the vicinity of the High-Mass Young Stellar Objects (HMYSOs). Monitoring this transition provides an only one opportunity to catch rare, unusual phenomena. In this paper, I describe three of them: quasi-periodic flares of the red-shifted emission in Cep A HW2, accretion burst in S255-NIRS3 and reappearance of the methanol maser flare in G24.329+0.144.

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Hanami, Hitoshi. "Nonlinear Oscillation of the Magnetosphere around Neutron Stars." International Astronomical Union Colloquium 108 (1988): 242–43. http://dx.doi.org/10.1017/s0252921100093969.

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SummaryWe investigate the unsteady motion of mass reservoir formed by the accretion onto the magnetosphere around rotating neutron stars. The unsteady motion of the reservoir induces secondary accretion to neutron star by R-T instability. The nonperiodic or quasiperiodic phenomena of X-ray bursters seems to be related to this property of mass reservoir on the magnetosphere. We classify the typical dynamical state of the reservoir into three types with the parameters which are accretion rate acc and angular velocity of neutron star Ωs. They are nonsequential oscillation, sequential periodic (qu

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Jovanovic, P. "Investigation of some galactic and extragalactic gravitational phenomena." Serbian Astronomical Journal, no. 185 (2012): 1–16. http://dx.doi.org/10.2298/saj1285001j.

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Here we present a short overview of the most important results of our investigations of the following galactic and extragalactic gravitational phenomena: supermassive black holes in centers of galaxies and quasars, supermassive black hole binaries, gravitational lenses and dark matter. For the purpose of these investigations, we developed a model of a relativistic accretion disk around a supermassive black hole, based on the ray-tracing method in the Kerr metric, a model of a bright spot in an accretion disk and three different models of gravitational microlenses. All these models enabled us t

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DONMEZ, ORHAN. "QUASI-PERIODIC OSCILLATIONS AND FREQUENCIES IN AN ACCRETION DISK AND COMPARISON WITH THE NUMERICAL RESULTS FROM NON-ROTATING BLACK HOLE COMPUTED BY THE GRH CODE." Modern Physics Letters A 22, no. 02 (2007): 141–57. http://dx.doi.org/10.1142/s021773230702138x.

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The shocked wave created on the accretion disk after different physical phenomena (accretion flows with pressure gradients, star-disk interaction etc.) may be responsible observed Quasi Periodic Oscillations (QPOs) in X-ray binaries. We present the set of characteristics frequencies associated with accretion disk around the rotating and non-rotating black holes for one particle case. These persistent frequencies are results of the rotating pattern in an accretion disk. We compare the frequency's from two different numerical results for fluid flow around the non-rotating black hole with one par

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Sniegowska, M., B. Czerny, E. Bon, and N. Bon. "Possible mechanism for multiple changing-look phenomena in active galactic nuclei." Astronomy & Astrophysics 641 (September 2020): A167. http://dx.doi.org/10.1051/0004-6361/202038575.

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Context. The changing-look phenomenon observed in a growing number of active galaxies challenges our understanding of the accretion process close to a black hole. Aims. We propose a simple explanation for the sources where multiple semi-periodic outbursts are observed, and the sources are operating close to the Eddington limit. Methods. The outburst are caused by the radiation pressure instability operating in the narrow ring between the standard gas-dominated outer disk and the hot optically thin inner advection-dominated accretion flow. The corresponding limit cycle is responsible for period

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Meier, D. L., P. Godon, S. Edgington, D. G. Payne, and K. R. Lind. "11.18. The magnetic switch and the FR I/FR II break." Symposium - International Astronomical Union 184 (1998): 491–92. http://dx.doi.org/10.1017/s0074180900085727.

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Chamandy, Luke, Adam Frank, Eric G. Blackman, et al. "Accretion in common envelope evolution." Proceedings of the International Astronomical Union 14, S343 (2018): 235–38. http://dx.doi.org/10.1017/s174392131800666x.

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AbstractCommon envelope evolution (CEE) occurs in some binary systems involving asymptotic giant branch (AGB) or red giant branch (RGB) stars, and understanding this process is crucial for understanding the origins of various transient phenomena. CEE has been shown to be highly asymmetrical and global 3D simulations are needed to help understand the dynamics. We perform and analyze hydrodynamic CEE simulations with the adaptive mesh refinement (AMR) code AstroBEAR, and focus on the role of accretion onto the companion star. We bracket the range of accretion rates by comparing a model that remo

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Kimura, Mariko, Takayuki Hayashi, Yuuki Wada, et al. "Evolution of the Inner Accretion Flow and the White Dwarf Spin Pulse during the 2023 Outburst in GK Persei." Astrophysical Journal 985, no. 2 (2025): 240. https://doi.org/10.3847/1538-4357/adcf27.

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Abstract We present our X-ray and optical observations performed by NICER, NuSTAR, and Tomo-e Gozen during the 2023 outburst in the intermediate polar GK Persei. The X-ray spectrum consisted of three components: blackbody (BB) emission of several tens of eVs from the irradiated white dwarf (WD) surface, a source possibly including several emission lines around 1 keV, and multitemperature bremsstrahlung emission from the accretion column. The 351.3 s WD spin pulse was detected in X-rays, and the observable X-ray flux from the column drastically decreased at the off-pulse phase, which suggests t

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Elbakyan, Vardan G., Sergei Nayakshin, Eduard I. Vorobyov, Alessio Caratti o Garatti, and Jochen Eislöffel. "Accretion bursts in high-mass protostars: A new test bed for models of episodic accretion." Astronomy & Astrophysics 651 (July 2021): L3. http://dx.doi.org/10.1051/0004-6361/202140871.

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Aims. It is well known that low-mass young stellar objects (LMYSOs) gain a significant portion of their final mass through episodes of very rapid accretion, with mass accretion rates up to Ṁ∗ ∼ 10−4 M⊙ yr−1. Recent observations of high-mass young stellar objects (HMYSOs) with masses M∗ ≳ 10 M⊙ uncovered outbursts with accretion rates exceeding Ṁ∗ ∼ 10−3 M⊙ yr−1. Here, we examine which scenarios proposed in the literature so far to explain accretion bursts of LMYSOs can also apply to the episodic accretion in HMYSOs. Methods. We utilise 1D time-dependent models of protoplanetary discs around HM

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MATSUMIYA, Hisato, Takashi NISHIHARA, Mikio SHIMIZU, Teruo ASO, and Teruhiro YUKINO. "Galloping Phenomena of Overhead Transmission Lines Under Snow and Ice Accretion." Wind Engineers, JAWE 37, no. 1 (2012): 27–33. http://dx.doi.org/10.5359/jawe.37.27.

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Al Farrizi, Abdurrahman, Ankiq Taofiqurohman, and Subiyanto Subiyanto. "Shoreline Change Analysis of Pontang Cape of Serang Regency of Banten Province." Omni-Akuatika 16, no. 2 (2020): 90. http://dx.doi.org/10.20884/1.oa.2020.16.2.800.

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Coastal areas, being vulnerable to environmental problems, have one of the most frequent problems which are the change in the shorelines. Shoreline changes, namely abrasions, can cause problems such as land degradations or loss of land in a coastal zone. This problem occurs in many areas, one of which is Pontang Cape. This study aims to determine the distance and rate of shoreline changes that occured in the Cape and its surroundings, as well as explaining the analysis points based on similar studies that had been conducted. This research used ArcMap software and Digital Shoreline Analysis Sys

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Orlando, Salvatore, Fabio Reale, Giovanni Peres, and Andrea Mignone. "Mass Accretion Processes in Young Stellar Objects: Role of Intense Flaring Activity." Acta Polytechnica CTU Proceedings 1, no. 1 (2014): 108–12. http://dx.doi.org/10.14311/app.2014.01.0108.

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According to the magnetospheric accretion scenario, young low-mass stars are surrounded by circumstellar disks which they interact with through accretion of mass. The accretion builds up the star to its nal mass and is also believed to power the mass out ows, which may in turn have a signicant role in removing the excess angular momentum from the star-disk system. Although the process of mass accretion is a critical aspect of star formation, some of its mechanisms are still to be fully understood. On the other hand, strong aring activity is a common feature of young stellar objects (YSOs). In

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Stuchlik, Zdenek, and Jan Schee. "ON OBSERVATIONAL PHENOMENA RELATED TO KERR SUPERSPINARS." Acta Polytechnica 54, no. 3 (2014): 254–58. http://dx.doi.org/10.14311/ap.2014.54.0254.

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We investigate possible signatures of a Kerr naked singularity (superspinar) in various observational phenomena. It has been shown that Kerr naked singularities (superspinars) have to be efficiently converted to a black hole due to accretion from Keplerian discs. In the final stages of the conversion process the near-extreme Kerr naked singularities (superspinars) provide a variety of extraordinary physical phenomena. Such superspinning Kerr geometries can serve as an efficient accelerator for extremely high-energy collisions, enabling a direct and clear demonstration of the outcomes of the co

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Beuermann, K., and U. Woelk. "Radiation Hydrodynamics of Accreting Magnetic White Dwarfs." International Astronomical Union Colloquium 158 (1996): 199–202. http://dx.doi.org/10.1017/s0252921100038616.

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AbstractWe solved the stationary one-dimensional two-fluid radiation hydrodynamic equations including cyclotron radiation for a wide range of mass flow rates. Here, we discuss the implications for accretion phenomena on the white dwarfs in AM Her binaries.

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Uchiyama, Mizuho, Kohei Ichikawa, Koichiro Sugiyama, Yoshihiro Tanabe, and Yoshinori Yonekura. "Mid-infrared and Maser Flux Variability Correlation in Massive Young Stellar Object G036.70+00.09." Astrophysical Journal 936, no. 1 (2022): 31. http://dx.doi.org/10.3847/1538-4357/ac866e.

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Abstract We present the discovery of the simultaneous flux variation of a massive young stellar object (MYSO) G036.70+00.09 (G036.70) both in the maser emission and mid-infrared (MIR; λ = 3–5 μm) bands. Using the ALLWISE and NEOWISE archival databases that cover a long time span of approximately 10 yr with a cadence of 6 months, we confirm that G036.70 indicates a stochastic year-long MIR variability with no signs of a WISE band color change of W1 (3.4 μm) −W2 (4.6 μm). Cross-matching the MIR data set with the high-cadence 6.7 GHz class II methanol maser flux using the Hitachi 32 m radio teles

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Linares, Manuel, Barbara De Marco, Rudy Wijnands, and Michiel van der Klis. "X-ray variability of transitional millisecond pulsars: a faint, stable, and fluctuating disc." Monthly Notices of the Royal Astronomical Society 512, no. 4 (2022): 5269–77. http://dx.doi.org/10.1093/mnras/stac720.

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ABSTRACT Transitional millisecond pulsars (tMSPs) have emerged in the last decade as a unique class of neutron stars at the crossroads between accretion- and rotation-powered phenomena. In their (sub-luminous) accretion disc state, with X-ray luminosities of order 1033–1034 erg s−1, they switch rapidly between two distinct X-ray modes: the disc-high (DH) and disc-low (DL) states. We present a systematic XMM–Newton and Chandra analysis of the aperiodic X-ray variability of all three currently known tMSPs, with a main focus on their disc state and separating DH and DL modes. We report the discov

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Zhou, Yifan, Brendan P. Bowler, Aniket Sanghi, et al. "Evidence for Variable Accretion onto PDS 70 c and Implications for Protoplanet Detections." Astrophysical Journal Letters 980, no. 2 (2025): L39. https://doi.org/10.3847/2041-8213/adb134.

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Abstract Understanding the processes of planet formation and accretion in young systems is essential to unraveling the initial conditions of planetary systems. The PDS 70 system, which hosts two directly imaged protoplanets, provides a unique laboratory for studying these phenomena, particularly through Hα emission, a commonly used accretion tracer. We present multiepoch observations and examine the variability in accretion signatures within this system, focusing on PDS 70 b and c. Using Hubble Space Telescope narrowband Hα imaging data taken in 2020 and 2024, we achieve high signal-to-noise r

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