IOPW minutes and summary of 2011-2012 activity in each sub-group
The International Outer-Planet Watch Steering Committee meeting was held on Monday evening over (and after) dinner in conjunction with the American Astronomical Society's Division for Planetary Science (DPS), Reno, Nevada, 2012 October 15.
Present were:
Glenn Orton (Chair)
Imke de Pater (permanent member)
Robert West (permanent member)
Ricardo Hueso (chair, Jupiter and Saturn atmospheres)
Mark Hofstadter, Heidi Hammel (incoming, outgoing chairs, Uranus and Neptune
atmospheres)
John Clarke (chair, auroral sub-discipline)
Franck Marchis (chair, satellite sub-discipline)
Kunio Sayanagi (incoming rotating member)
Unable to attend the DPS were:
Chris Russell (permanent member)
Henry Roe (chair: Titan atmosphere)
Reports from each of the sub-groups are reported below:
IOPW Aurora/Torus-Magnetosphere sub-discipline
Update Oct 2012
The concentration of effort in the past year has been at Saturn,
in no small part owing to the continuing Cassini mission.
The status of the discipline was reported at the July 2011
Magnetospheres of the Outer Planets conference, held at Boston
University (http://www.bu.edu/csp/mop2011). There have been
few observations of the plasma torus in the past year, and only
scattered observations of Jupiter's aurora, mainly using HST and
ground-based IR telescopes.
By contrast, an HST program to detect aurora on Uranus was successful, for the first time since the Voyager 2 flyby in 1986! (Lamy et al. 2012). This program attempted to trace a disturbance in the solar wind from 1 AU out to Uranus, and the HST orbits were scheduled to bracket the expected arrival time. Whether this worked or not, auroral emissions were clearly detected on one day, and weakly detected at other times. A new HST program has been awarded in the present cycle to follow up on these observations.
At Saturn, further coordinated HST and Cassini UVIS and VIMS observations are scheduled, and these programs have been very successful to date. In the first years of Cassini at Saturn, there were few UV/IR observations of the aurora, but the number has been increasing over the years, and is now a common mode for Cassini. The lead people are Jon Nichols for the HST, Wayne Pryor for UVIS, and Tom Stallard for VIMS. The detection of auroral emission from the magnetic footprint of Enceladus at Saturn was a big event in the prior year.
A Few Publications:
W. Pryor, A. B. Rymer et al. 2011. Discovery of the Enceladus auroral
footprint
at Saturn.
Nature 472, 331-333, doe_10.1038/nature09928.
B. Bonfond, D. Grodant, J.-C. Gerard, T. Stallard, J.T. Clarke, M. Yoneda, A.
Radioti, and
J. Gustin. 2012. Auroral Evidence of Io's control over the magnetosphere of
Jupiter. Geophys.
Res. Lett. 39, L01105, doi: 10.1029/2011GL050253.
L. Lamy et al. 2012. Earth-based detection of Uranus aurorae. Geophys. Res.
Lett. 39, L07105,
doi:10.1029/2012GL051312.
John Clarke, will continue as head of the Aurora discipline. However, he suggested that Andrew Steffl take over as head of a new (actually partly an old, but revived) discipline: Torus and Magnetosphere. This was explicitly approved by Nick Schneider, a former IOPW member. Andrew has taken on the task of organizing Earth-based support for the imminent EXCEED mission studying the Io torus, and he would have greater effectiveness with the imprimatur of the IOPW. This idea hasn't met any objections from the Steering Committee, and the Chair recognizes it as a great idea and timely activity.
IOPW Ice Giants sub-discipline, reported by Mark Hofstadter and Heidi Hammel:
In general, we note that a range of observations and new analyses this year have both advanced and challenged our understanding of the Ice Giants, and shown them to be dynamic objects. A combination of new technology and improved techniques continues to advance the capabilities of ground- and space-based instruments.
Recent Uranus Items.
*UV imaging. Hubble imaging, timed to coincide with the arrival of a solar wind shock front at Uranus, imaged auroral arcs for the first time since the Voyager encounter in 1986. See Lamy et al. 2012, GRL.
*Visible/Near IR imaging. Using HST, Keck, and the Gemini telescopes, several intriguing new cloud structures were seen. The North Polar region appears covered by small-scale convective towers surrounded by featureless regions (of downwelling?) reminiscent of Saturn's polar regions. These structures were not seen over Uranus' South Pole. One (perhaps two) bright/dark-spot complexes were seen to be in the same high-northern latitude band, but moving at different longitudinal rates; one dark spot was detected with Hubble; a second is not clearly detected and is being discussed. The two features passed each other and appeared to brighten during their interaction. (See Sromovsky et al. 2012a, Icarus 220, 6; Sromovsky et al. 2012b Icarus 220, 694.) An equatorial band, when high-pass filtered to emphasize small-scale features, clearly shows a periodic scalloped edge, indicative of a high-order planetary wave. (See Fry et al and Sromovsky et al. DPS poster and talk)
Two bright spots were seen to be in the same high-northern latitude band, but moving at different longitudinal rates; the region brightened significantly when the spots passed each other. Unfortunately, after the discovery, and when observations were planned during the interaction, the original bright spot had faded, and the second one appeared to be a companion of a dark spot, the second such spot ever seen on Uranus. (See Sromovsky et al. 2012, Icarus 220.)
*Far-IR/Sub-millimeter observations of stratospheric hydrocarbons with Herschel show no longitudinal variability. Two widely-spaced observing sequences with Spitzer a few years ago showed clear longitudinal structure that decreased over time. These observations are consistent with a localized (in time and space) injection of hydrocarbons years ago which has since dispersed.
*Over the past decade, several models of cloud altitudes have been proposed based on visible/near-IR spectroscopy. Assuming an equilibrium cloud condensation model, these cloud altitudes were translated into vapor mixing ratios and tested against radio-wavelength observations. It was found that some cloud models could be excluded. (Mihalka et al. 2013, submitted to PSS.)
*Recent laboratory work on the microwave opacity of gases indicates the pressure broadening of NH3 lines by CH4 and H2O is significantly higher than previously thought---see DPS 2012 talk by D. Devaraj.
Recent Neptune items:
*Imaging at millimeter wavelengths with the SMA has probed the spatial variability of stratospheric HCN, which is much different than the uniform CO distribution. (This is work in progress reported by A. Moullet and I. de Pater.)
* Near-IR imaging with the Keck AO system is continuing; there is much variability in the detailed cloud structure over time. Cloud speeds have been measured, and again confirm the large dispersion of velocities for clouds at the same latitudes. (Fitzpatrick et al., in preparation).
*Centimeter wavelength observations with the JVLA shows the continued large depletion of condensible species in the troposphere over the South Pole and---clearly resolved for the first time---a similar depletion in a band around the equator. See DPS 2012 presentations by J. Norwood and B. Butler.
Mid-infrared low-resolution spectroscopy of Neptune continues at the NASA
IRTF, and show post
solstice decrease in temperature, with unchanging temperatures over the past
4 years (through
2011)
Continued imaging has happened for Neptune with Keck observatory.
Mark Hofstadter will rotate into Heidi's role as Ice Giant sub-discipline chair.
IOPW Laboratory sub-discipline, reported by Kiruthika Devaraj (filling in for Paul Steffes):
The following are the updates from the Georgia Tech laboratory measurement campaign:
1. Measurements of the 5-20 cm wavelength opacity of ammonia, and ammonia pressure-broadened by water vapor under simulated jovian conditions were completed, modeling is almost completed (Oral presentation on Friday am). Model predicts that the effect of water vapor on ammonia opacity in the microwave region is five times as much as hydrogen and about nine times as much as helium. This work will impact the Juno MWR retrievals and also the retrievals of abundances from the deep atmosphere of the other outer planets.
2. Measurements of the 5-20 cm wavelength opacity of ammonia pressure-broadened by methane under simulated jovian conditions were conducted by Garrett Chinsomboon and a new model was developed (Poster presentation on Thursday pm). These measurements verified that the effect of additional opacity from ammonia pressure-broadened by methane is low and would not affect the MWR measurements at Jupiter. However, these results will significantly improve the understanding of the microwave emission spectrum of Uranus and Neptune where methane plays a more dominant role.
3. Measurements of 5-20 cm wavelength opacity of methane under jovian conditions were conducted by Garrett Chinsomboon. The measurements verified that methane's centimeter-wavelength opacity is extremely low, and would not affect the Jovian microwave emission measured by Juno MWR. These results will improve the understanding of the microwave emission spectrum of Uranus and Neptune.
4. Measurements of H2S in an H2 atmosphere at a temperature of 375 K and with pressures reaching 20 Bars were conducted by Garrett Chinsomboon and Patrick Shahan. These data verified the accuracy of the DeBoer and Steffes (1994) model under deep jovian conditions and indicate that the presence of H2S should not significantly effect the retrieval of water vapor abundance with the Juno MWR.
IOPW Satellites sub-discipline, reported by Franck Marchisp Observations in 2010-2011
Io monitoring has been continuing with sporadic observations using W.M. Keck AO telescope from Imke de Pater, myself and others usning the NIRC2 camera. The data can be retrieved on the Keck Archive http://www2.keck.hawaii.edu/koa/public/koa.php A dedicated program was conducted at Gemini North (PI: Imke de Pater). Nine epochs of observation were recorded fron Aug 2010 to Jan 2011, the data are being analyzed by Imke de Pater and myself.
Observations in 2012
No observation of Io reported at Keck. I found a few observations at Gemini North in the archive (PI: Imke de Pater) but I don't know much about it (even if I was co-I on the proposal).
I spent a considerable amount of my time advocating solar system observations, including Io, for the next generation AO system at Keck, Gemini North, Gemini South and TMT (e.g. review talk at the SPIE conference in 2012)
Recent results:
* Marchis & Davies presented at the 2012 DPS conference a global analysis of
44 epochs of
observations of Io taken since 2003. Key results are:
- The presence of 12 hotspot between lat 40S & lat 40N always active
- A bright and unknown outburst in May 2004
- The monitoring of Tvashtar eruption which lasted more than 530 days
- A quiescent activity of Io in 2010-2011 with the absence of young
eruptions and bright outbursts
- Simulation of observations with the TMT
see http://phys.org/news/2012-10-io-insane-volcanic-comfort-earth.html
Publications are in progress
Future:
During the last Io workshop (July 2012), a campaign to observe Io in 2013-2015 has been set up since a Japanese mission (EXCEED) dedicated to the monitoring of Jupiter atmosphere will be launched in Nov 2013. Several groups are coordinating their efforts which include AO observations with 8-10m class telescopes (hot spot activity), IRTF monitoring (outbursts) and HST (plumes & atmosphere).
Frank suggested that he would like to resign from the IOPW Io leadership,
with Julie Rathbun
(University of Redlands;
Julie_Rathbun@redlands.edu
IOPW Steering Committee Atmospheres Node, reported by Ricardo Hueso
Jupiter has experienced important morphological changes over the last solar
conjunction in the
Equatorial Zone, North Equatorial Belt and North Temperate Belt regions. Most
of these changes
have been followed by IRTF and observations in the visible range acquired by
amateur
astronomers.
HST observed Jupiter over 16 orbits in September 19th and 20th 2012 for a
Venus transit
research program. Observations were carried on in 763 and 275 nm wavelengths
and preliminary
reports have been presented measuring winds in Jupiter with these images (N.
Barrado-Izagirre
and A. Sanchez-Lavega). Besides the regular observation program carried by G.
Orton and his
team using the IRTF no other major observations have been reported over 2010
for Jupiter.
The last 2 year have seen a large involvement of amateur astronomers in major
discoveries
related with Jupiter and Saturn. Those amateur achievements have attracted
more amateurs to
this field and has served to impulse a global improvement in observation
quality. Particular
important events have been the successive discoveries of impacts in Jupiter
starting with the
large (0.5-1 km) impact discovered by Anthony Wesley from Australia and
continuing with three
detections of much smaller objects colliding with Jupiter and forming bright
and short
fireballs (June 2010, August 2010 and September 2012). Quality of amateur
observations has also
improved largely because of recent improvements in software processing
programs able to
co-register and stack thousands of images or to derotate video observations
of Jupiter
(WinJupos). Since 2011 it is possible to monitor Jovian winds with amateur
images on a nearly
regularbasis (results obtained by N. Barrado-Izagirre). Amateurs
collaborating with the
Planetary Sciences Group in Bilbao have developed a software to process video
observations of
Jupiter and detect impacts on them. The software will be available to the
large amateur
community in a short time through the PVOL database of images and usual
e-mail lists. The
Jupiter community relies so much in amateur observations of Jupiter that the
DPS and/or EPSC
should considernominating a prize for achievements in planetary science
astronomy done by an
amateur. The IOPW should collaborate more closely with the community of
Japanese amateur
astronomers who constitute an excellent group of observerswell organized
through ALPO Japan but
difficult to reach due to language problems. K. Sayanagi offered to help in
this subject.
Professional astronomers in the field of observations of Jupiter in visible
wavelengths are
also improving their capabilities to observe Jupiter. Some relevant examples
follow. The
Planetary Sciences Group in Bilbao has developed a fast lucky imaging camera
for the specific
purpose of achievingregularly in time diffraction limited images of Jupiter
in 1-m class
telescopes. Other groups (K. Sayanagi and F. Marchis in USA and O. Mousis in
France) are
developing proposals to build observing networks with several telescopes on
the range 16-20.
Kunio Sayanagi, newly appointed rotating member, first discussed his
Networked Extended
Temporal Survey Telescopes for Planetary Science (NExTSTePS) proposal that is
currently
pending with NSF's Faculty Early Career Fellowship program. His proposal
aims to increase
the temporal coverage of the outer planets (currently aimed primarily for
Jupiter and
Saturn) by linking multiple telescopes distributed along longitudes on Earth,
and
automating the observation and data reduction pipeline. His current proposal
will link
telescopes in Bilbao Spain (managed by the Sanchez-Lavega group), Fan
Mountain Observatory
in Virginia (Managed by University of Virginia, and currently operated by
Norfolk State
University), and Mount Wilson Observatory (Managed and operated by Georgia
State University).
His plan will automate the data acquisition, reduction, and archiving; the
goal is to
minimize human intervention and maximize the temporal observational coverage.
Second, Kunio volunteered to reach out to the Japanese community of amateur
observers.
Language barrier has been a major issue in communicating with the Japanese
community.
Kunio speaks and writes Japanese fluently, so he volunteered to serve as a
bridge between
ALPO-Japan and the rest of IOPW.
Third, Kunio discussed potential observing opportunities at Mount Wilson
Observatory in
Pasadena, California. Mount Wilson is known for the legendary seeing
conditions (Glenn
did his PhD work using the 60-inch telescope!). Currently, Mount Wilson is
managed by
Mount Wilson Institute, which is a non-profit organization based at Georgia
State University.
The primary operation at the site today is the Center for High Angular
Resolution Astronomy
(CHARA), who does optical interferometric imaging. The observatory has two
large telescopes,
the 60-inch and 100-inch. The 60-inch is used primarily used for outreach,
while the
100-inch is largely unused. The astrophysics community has lost interest in
the telescopes
when the light pollution became an issue at the site; however, because of the
seeing, the
site still has a good potential for planetary observing. Kunio has
connections with the
observatory (his band's leader is the associate director of the observatory,
and he's also
a good friend with the person who designed and constructed the AO for the
100-inch) so he
may be able to negotiate some trial observation if we can provide
instrumentation. The
steering committee agreed that it seems like an opportunity to look into.