LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Search results

Result 1 - 2 of total 2

Search options

  1. Article ; Online: Occultation of X-rays from Scorpius X-1 by small trans-neptunian objects.

    Chang, Hsiang-Kuang / King, Sun-Kun / Liang, Jau-Shian / Wu, Ping-Shien / Lin, Lupin Chun-Che / Chiu, Jeng-Lun

    Nature

    2006  Volume 442, Issue 7103, Page(s) 660–663

    Abstract: Since the discovery of the trans-neptunian objects (TNOs) in 1992, nearly one thousand new members have been added to our Solar System, several of which are as big as--or even larger than--Pluto. The properties of the population of TNOs, such as the size ...

    Abstract Since the discovery of the trans-neptunian objects (TNOs) in 1992, nearly one thousand new members have been added to our Solar System, several of which are as big as--or even larger than--Pluto. The properties of the population of TNOs, such as the size distribution and the total number, are valuable information for understanding the formation of the Solar System, but direct observation is only possible for larger objects with diameters above several tens of kilometres. Smaller objects, which are expected to be more abundant, might be found when they occult background stars, but hitherto there have been no definite detections. Here we report the discovery of such occultation events at millisecond timescales in the X-ray light curve of Scorpius X-1. The estimated sizes of these occulting TNOs are < or =100 m. Their abundance is in line with an extrapolation of the distribution of sizes of larger TNOs.
    Language English
    Publishing date 2006-08-10
    Publishing country England
    Document type Journal Article
    ZDB-ID 120714-3
    ISSN 1476-4687 ; 0028-0836
    ISSN (online) 1476-4687
    ISSN 0028-0836
    DOI 10.1038/nature04941
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    In stock of ZB MED Cologne/Königswinter

    Zs.A 26: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)
    Zs.MG 9: Show issues
    Zs.MO 244: Show issues

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  2. Article ; Online: Repetitive patterns in rapid optical variations in the nearby black-hole binary V404 Cygni.

    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 / de Miguel, Enrique / 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 / Uemura, Makoto

    Nature

    2016  Volume 529, Issue 7584, Page(s) 54–58

    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. ... ...

    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.
    Language English
    Publishing date 2016-01-07
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 120714-3
    ISSN 1476-4687 ; 0028-0836
    ISSN (online) 1476-4687
    ISSN 0028-0836
    DOI 10.1038/nature16452
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    In stock of ZB MED Cologne/Königswinter

    Zs.A 26: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)
    Zs.MG 9: Show issues
    Zs.MO 244: Show issues

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

To top