Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.stsci.edu/~marel/abstracts/psdir/STScI_anrep00_vdM.ps Дата изменения: Fri Apr 6 18:07:03 2001 Дата индексирования: Sat Dec 22 17:16:44 2007 Кодировка: Поисковые слова: rings

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The Demography of
Supermassive Black Holes
Roeland van der Marel
S upermassive black holes in the centers of galaxies are
some of the most enigmatic objects in the universe. In
active galaxies and quasars, their appetite for matter provides
us with a stunning display of fireworks, including X­ray
emission, radio jets, and rapidly moving gas clouds. In normal
galaxies, starved of fuel, they lurk quiescently.
The Hubble Space Telescope has revolutionized our
knowledge of these supermassive black holes. By measuring
the motions of stars and gas in the centers of galaxies, Hubble
has not only proven their existence but also determined their
masses. The Space Telescope Imaging Spectrograph (STIS)
is particularly well suited for such studies. STIS is now allow­
ing us to address the demography of the supermassive black
hole population.
A special session entitled ``Supermassive Black Hole
Research and Advances with STIS'' at the American Astro­
nomical Society meeting in Rochester drew together
astronomers to discuss newly emerging results. Earlier reports
were confirmed that supermassive black holes may well exist
in all galaxies, and that the black hole mass correlates loosely
with the mass of the galaxy bulge. In addition, two groups
independently reported a strong correlation between the
mass of the black hole in a galaxy and the magnitude of the
random motions of its stars.
These results provide new insight into the origin of
supermassive black holes. One plausible scenario is that
galaxies and their black holes form simultaneously in an
phase that manifests itself through strong quasar activity.
This is quantitatively consistent with the statistics of quasars
in the distant universe and with the statistics of black holes
in the nearby universe.
In the coming years, further studies of supermassive
black holes using STIS will undoubtedly bring a clearer
understanding of the origin and demographics of these
remarkable objects.
Fireworks around Supernova 1987A
Nino Panagia
S upernova 1987A exploded on 1987 February 23 in the
Large Magellanic Cloud. Although Hubble was not yet
in orbit when this rare chance to observe a nearby supernova
appeared, it took advantage of the opportunity as soon as it
became operational. The European Space Agency's Faint Object
Camera took the first images of SN 1987A on 1990 August
23­24, which revealed the supernova crowned by a glorious
circumstellar ring. Later, two more rings were discovered.
Hubble has kept an attentive eye on SN 1987A. Hubble
observations have produced many fundamental results, includ­
ing a direct measure of the supernova expansion, the detailed
properties of its surrounding rings, the distance to the super­
nova, and the origin of the stars associated with the supernova.
Recently, Hubble has observed the high velocity material
from the supernova explosion starting to overtake and crash
into the slower moving inner ring. The accompanying images
show the dramatic evidence of these collisions. The circum­
stellar ring, which until 1995 was relatively quiescent (left
panel), started to develop bright spots in 1997. In November
2000 (right panel), one can identify almost a dozen bright
spots due to interactions between the material ejected by the
supernova and the ring material. Within the decade ahead,
the full force of the supernova's fast material will hit the
whole inner ring, heating and exciting its gas to produce a
new series of cosmic fireworks. Hubble will take pictures of
this spectacular scene until its end of life in 2010.
True color images of SN 1987A and its inner circumstellar ring obtained with
Hubble's Wide Field Planetary Camera 2 in May 1995 (left) and November
2000 (right). These images show that the quiescent ring has developed a number
of new hot spots in the last five years. In a few more years the entire ring will be
glowing much more brightly. [Courtesy of Peter Challis (Center for Astrophysics),
on behalf of the SINS project. (Supernova INtensive Study, PI: R.P Kirshner)]
6
Star
Star
1
7
8
2
3
9
4
5
10?
11?
New Collision Spots 1 ­ 11
HST/WFPC2 May 1995 HST/WFPC2 Nov 2000
Supermassive black holes exist in the centers of many---perhaps all---galaxies.
Recent results suggest that the mass of the black hole increases with the mass of the
spheroidal bulge component of the galaxy. If the black hole is accreting material,
the galaxy is identified as an active galaxy or a quasar.
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