SEDNA MYSTERY DEEPENS WITH HUBBLE IMAGES OF FARTHEST PLANETOID (STScI-PR04-14)

EMBARGOED UNTIL: 1:00 pm (EDT) April 14, 2004

Don Savage
NASA Headquarters, Washington
(Phone: 202-358-1547; )

Ray Villard
Space Telescope Science Institute, Baltimore, MD
(Phone: 410-338-4514; )

Robert Tindol
California Institute of Technology, Pasadena, CA
(Phone: 626-395-3631; )

Janet Emanuel
Yale University Office of Public Affairs, New Haven, CT
(Phone: 203-432-2157; E-mail: )

PRESS RELEASE NO.: STScI-PR04-14


SEDNA MYSTERY DEEPENS WITH HUBBLE IMAGES OF FARTHEST PLANETOID

Astronomers poring over 35 NASA Hubble Space Telescope images
of the solar system's farthest known object, unofficially named
Sedna, are surprised that the object does not appear to have a
companion moon of any substantial size. This unexpected result might
offer new clues to the origin and evolution of objects on the far edge
of the solar system.

To see and read more about Sedna, please visit:
http://hubblesite.org/news/2004/14

The Space Telescope Science Institute (STScI) is operated by the
Association of Universities for Research in Astronomy, Inc. (AURA),
for NASA, under contract with the Goddard Space Flight Center,
Greenbelt, MD. The Hubble Space Telescope is a project of international
cooperation between NASA and the European Space Agency (ESA).

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thanks - nice post.





INBOX ASTRONOMY: NEWS ALERT wrote:

EMBARGOED UNTIL: 1:00 pm (EDT) April 14, 2004

Don Savage
NASA Headquarters, Washington
(Phone: 202-358-1547; )

Ray Villard
Space Telescope Science Institute, Baltimore, MD
(Phone: 410-338-4514; )

Robert Tindol
California Institute of Technology, Pasadena, CA
(Phone: 626-395-3631; )

Janet Emanuel
Yale University Office of Public Affairs, New Haven, CT
(Phone: 203-432-2157; E-mail: )

PRESS RELEASE NO.: STScI-PR04-14

SEDNA MYSTERY DEEPENS WITH HUBBLE IMAGES OF FARTHEST PLANETOID

Astronomers poring over 35 NASA Hubble Space Telescope images
of the solar system's farthest known object, unofficially named
Sedna, are surprised that the object does not appear to have a
companion moon of any substantial size. This unexpected result might
offer new clues to the origin and evolution of objects on the far edge
of the solar system.

To see and read more about Sedna, please visit:
http://hubblesite.org/news/2004/14

The Space Telescope Science Institute (STScI) is operated by the
Association of Universities for Research in Astronomy, Inc. (AURA),
for NASA, under contract with the Goddard Space Flight Center,
Greenbelt, MD. The Hubble Space Telescope is a project of international
cooperation between NASA and the European Space Agency (ESA).

To receive STScI Inbox Astronomy: News Alert messages, visit
http://hubblesite.org/newscenter/mailing.php or send an e-mail to
. Leave the subject line blank, and type the
word SUBSCRIBE in the body of the message. The system will respond with
instructions on how to confirm your subscription. Once you follow the
instructions, you will receive news alerts as they are issued. Alerts
will be sent to the e-mail address you use to subscribe. To unsubscribe,
send e-mail to . Leave the subject line blank,
and type the word UNSUBSCRIBE in the body of the message. Please
unsubscribe using the email account that you used to subscribe to the
list

CeeBee wrote:
INBOX ASTRONOMY: NEWS ALERT wrote in
sci.astro.amateur:

SEDNA MYSTERY DEEPENS WITH HUBBLE IMAGES OF FARTHEST PLANETOID

Astronomers poring over 35 NASA Hubble Space Telescope images
of the solar system's farthest known object, unofficially named
Sedna, are surprised that the object does not appear to have a
companion moon of any substantial size. This unexpected result might
offer new clues to the origin and evolution of objects on the far edge
of the solar system.

To see and read more about Sedna, please visit:
http://hubblesite.org/news/2004/14

The description of the pictures mentions the upper limit of Sedna at
1000 miles, because it covers one pixel.
On the larger pics indeed one pixel a bit of center, is the brightest,
but there are many more pixels visible.

Given my very limited knowledge of CCD could someone explain why they
assume based on this picture that Sedna only covers "one pixel"?

The high-resolution mode of the Advanced Camera has very tiny pixels in
angular scale (0.027 arcseconds on a side), so that even the HST optics
give a diffraction pattern several pixels across. From this set of pixel
values, one can ask how large a disk the object could have without the
observed "spot" being larger than you'd get from a completely unresolved
object (say a random star, which get observed often). (To be more picky,
you could do a best-fit of the diffraction pattern at the relevant
wavelength convolved with a set of assumed disk sizes.)

A similar effect shows up in visual observations of the Galilean moons -
you can tell they look bigger than stars even in apertures that
cannot cleanly resolve their disks.

Bill Keel

WMConnect has a short display area for the title of a thread, so on my PC it
reads:
SEDNA MYSTERY DEEPENS WITH HUBBLE IMAGES OF FART
g
Clear, Dark, Steady Skies!
(And considerate neighbors!!!)

"Wfoley2" wrote in message
...
WMConnect has a short display area for the title of a thread, so on my PC
it
reads:
SEDNA MYSTERY DEEPENS WITH HUBBLE IMAGES OF FART
g

Now that is funny!
G

Clear, Dark, Steady Skies!
(And considerate neighbors!!!)

Clear Skies to you to!
Tom Wales

(Wfoley2) wrote in message ...
WMConnect has a short display area for the title of a thread, so on my PC it
reads:
SEDNA MYSTERY DEEPENS WITH HUBBLE IMAGES OF FART
g

So, methane. Must be life on Sedna.

Alan Harris had some interesting comments about this news release on the Minor
Planet Mail List (MPML). He pointed out two major errors. One error, was the
assertion that 2003 VB12's rotational period (~40 days, according to the press
release) is the slowest for a minor body in the solar system. 288 Glauke has a
period of around 1200 hours (50 days). 1220 Crocus has a rotational period of
737 hours (~31 days).

But the most glaring error, according to Harris, is the assumption that the
best explanation for a minor planet with a rotational period of that length is
tidal friction from interaction with a satellite. Harris wrote, "Tidal friction
is physically incapable of slowing the spin of a solid body to a period as long
as 40 days. Even the Earth, which is big and squishy, has stalled out with the
moon only out to a 28 day period. If the moon were bigger, the Earth-Moon
system would have synchronized (like Pluto-Charon) at a shorter period; if the
moon were smaller, it wouldn't have gotten out even as far as a 28 day period
in 4.5 b.y. For smaller planets, or ones without oceans, the tidal effect is
weaker so the maximum period that can be reached is even shorter. If
Charon were not much smaller, the Pluto-Charon pair would have stalled out by a
rotation/orbit period of a week or a bit more. You just can't get to a 40 day
spin-orbit period with a body that size."

Finally, Harris called attention to the fact that data have not been released
to support the public claims about 2003 VB12. And until those data are
released, such public claims should be viewed with skepticism.

Regards,

Bill Ferris
"Cosmic Voyage: The Online Resource for Amateur Astronomers"
URL: http://www.cosmic-voyage.net
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