SONG Workshop program

Sponsored by Danish Asteroseismology Center (DASC) and Instrumentcenter for Dansk Astrofysik (IDA)

Monday 20.03.2006




18:00 -21:00 Welcome reception and Registration


Tuesday 21.03.2006




09:00 -10:00 Registration and coffee

10:00 -12:30 Session I: Networks, continuous observations (Chair: Frank Grundahl)
10:00 -10:05 Welcome - J. Christensen-Dalsgaard
10:05 -10:40 The GONG experience - F. Hill
10:40 -11:20 The Birmingham Solar-Oscillations Network - B. Miller
11:20 -12:05 SIAMOIS: asteroseismic network with 1 site ...in Antarctica - B. Mosser
12:05 - 12:30 ICE-T: the International Concordia Explorer Telescope - K.G.Strassmeier, H. Korhonen, M.I. Andersen, (all AIP), A. Herber (AWI)*

12:30 -14:00 Lunch

14:00 -15:30 Session II: Networks and science (Chair: Michael Andersen)
14:00 -14:30 The stellar background noise in intensity and velocity - Hans Kjeldsen
14:30 -15:00 The SONG project, baseline design - Frank Grundahl
15:00 -15:30 An optical field station at 78N - a possible site for testing SONG equipment - Jan-Erik Solheim

15:30 -16:00 Coffee

16:00 -18:00 Session III: Exo-planet science (Chair: Travis Metcalfe)
16:00 -16:35 Planet science possibilities with SONG - Uffe Gråe Jørgensen
16:35 -17:15 Search for planets around G-type giants with EAPSNET - B. Sato
17:15 -17:30 Chaos and planet-particle dynamics within the habitable zone of extrasolar planetary systems - T. Hinse
17:30 -17:45 Improving the microlensing early alert system for extrasolar planet search campaigns with application to SONG follow-up observations - T. Hinse

19:00 Conference dinner


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Wednesday 22.03.2006




10:00 -12:15 Session IV: Asteroseismology I (Chair: Søren Frandsen)
10:00 -10:45 Asteroseismology --- multi-site results experience - T. Bedding
10:45 -11:15 Coffee

11:15 -11:50 Asteroseismology in China - J. Fu
11:50 -12:30 Asteroseismology --- the new hunting ground - Jørgen Christensen-Dalsgaard

12:30 -13:45 Lunch

13:45 -15:30 Session V: Asteroseismology II (Chair: Hans Kjeldsen)
13:45 -13:55 SONG additional science program - S. Frandsen
13:55 -14:35 Main-sequence pulsators and their asteroseismic prospects with SONG - G. Handler
14:35 -15:15 Stellar activity and SONG - H. Korhonen
15:15 -15:30 On some properties of solar-like oscillations- G. Houdek

15:30 -16:00 Coffee, Tea

16:00 -18:10 Session VI: Asteroseismology III (Chair: Werner W. Weiss)
16:00 -16:30 Envelope modelling of roAp stars in 3D - L. Freyhammer
16:30 -17:15 Precision radial velocities for giant stars - A. Quirrenbach
17:15 -17:50 GRB/SN science potentials for SONG - J. Fynbo
17:50 -18:10 The Hermes spectrograph - J. De Ridder


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Thursday 23.03.2006




09:00 -12:30 Session VII: Instruments, new concepts (Chair: Jørgen Christensen-Dalsgaard)
09:00 -09:45 An All Sky Extrasolar Planet Survey with New Generation Multiple Object Doppler Instruments at the Sloan Telescope and Its Follow-ups - J. Ge
09:45 -10:20 BRITE-Constellation: a counterpart of SONG in space - W. Weiss
10:20 -10:50 Coffee

10:50 -11:30 High resolution spectrographs for SONG - P. Spano', G. Toso, F.M. Zerbi
11:30 -12:15 Parasitic science with SONG - M. I. Andersen

12:30 -14:00 Lunch

14:00 Discussions among prospective partners of SONG specific issues






Friday 24.03.2006




Continued discussions
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ABSTRACTS




The Gong experience - F. Hill

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The Birmingham Solar-Oscillations Network - B. Miller

The Birmingham group has been observing solar oscillations since 1976 using the resonance-scattering technique. Our six-station network was completed in 1992 and consists of two coelostat-fed systems and four fully automated, equatorial-mounted systems in 12.5-foot astronomical domes. In this talk, I'll describe the automation electronics and software and how we built the network. I'll also talk about some of the things we learned and the problems we encountered along the way.

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SIAMOIS : an asteroseismic network with 1 site... in Antarctica - B. Mosser

SIAMOIS is an instrumental project devoted to ground-based asteroseismology, to be installed at the Dome C station in Antarctic. SIAMOIS will carry unique informations on G and K type bright stars in the main sequence, that will not be observed by COROT. Furthermore, pectrometric analysis with SIAMOIS will be complementary to the space photometric observations. The SIAMOIS concept is based on Fourier Transform interferometry. Such a principle leads to a small instrument designed and developped for the harsh conditions in Antarctic. The instrument will be highly automatic, with no moving parts, and a very simple simple set up in Antarctic. The single dedicated scientific programme will avoid the complications related to a versatile instrument. The data reduction will be realized in real time, and the transfer of the asteroseismic data to Europe will need a reduced bandpass. SIAMOIS will observe with a dedicated small 40-cm telescope. Dome C appears to be the ideal place for ground-based asteroseismic observations. The unprecedented good weather gives a duty cycle as high as 90%, as was observed during the 2005 wintering. This duty cycle, a crucial point for asteroseismology, is similar to the best space observations. Long time series (up to 3 months) will be possible. The funding of the ANR programme will permit to initiate the project, with the construction and installation of the instrument within 2.5 years, under the supervision of the LESIA laboratory, expert in space instrumentation. The SIAMOIS project is intended to participate to the very first observational projects in astronomy at Dome C. Its scientific programme will fully benefit from the unique quality of this site, and will constitute a first step preparing programmes requiring a more sophisticated instrumentation and a greater collector.

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ICE-T: the International Concordia Explorer Telescope - K.G.Strassmeier, H. Korhonen, M.I. Andersen, (all AIP), A. Herber (AWI)*

*ICE-T is a joint project for atmospheric and astrophysical research in Antarctica. It indents to measure aerosol densities and exo-planetary transits by means of high-precision stellar photometry. Our astrophysical goal is to perform a stellar variability survey between 9-19^th mag along three representative star fields in the Milky Way. Each field would be continuously observed for the entire polar night of approximately 100 ¿regular nights¿. The core scientific objective is to detect transits of extra-solar planets and investigate the combined effects of planets, stellar magnetic activity and non-radial pulsations on the structure and evolution of stars. In the initial field, we envision a photometric precision of up to 0,2 mmag for about 1,000 stars, 0.3-1mmag for 30,000 stars and 1-4 mmag for another almost 70,000 stars simultaneously in Sloan /g¿ /and /i¿ ///. Nominal time resolution would be between 20sec and 300sec, depending upon the choice of CCD co-adding and the on-site disk space, thus enabling detailed asteroseismology applications in the FOV.

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The stellar background noise in intensity and velocity - Hans Kjeldsen

The capability for a given instrument to detect short periodic p-mode signals and longer period variations in velocity due to orbiting planets will depend not only on the signal strength but also on the intrinsic noise level. For high frequencies one may be limited by the instrumental noise levels (and photon noise limits), however for longer period variations any star we want to observe may contain a stellar background noise source that will provide an ultimate limit for the detection of long period oscillations (g-modes) and detection of low-mass planets orbiting a given star. In this talk I will discuss the type of noise sources that one will expect to find in a long time series observation of a star. I will discuss the effect of granulation, activity and rotation and I will estimate the size of different noise sources using solar data from different experiments. Finally I will estimate the limits that one will experience when we try to detect low amplitude signals at longer periods and I will show that there will be no chance of detecting an Earth-mass planet in an Earth-like orbit. The stellar noise is expected to be an order of magnitude too high for this to be possible.

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The Stellar Oscillations Network Group -- Basic outline of SONG - Frank Grundahl

The current baseline of SONG is described, along with the expected capabilities for measuring velocities. We will describe the basic choices for the network and the motivation behind these and some of the options which are still open.

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An optical field station at 78N - a possible site for testing SONG equipment - Jan-Erik Solheim

Near Longyearbyen which is situated on Svalbard at 78N, there is an optical field station for auroral research. This station hosts a number of optical instruments, mostly doing automatic recordings of various kinds, in addition to more intense use during campaigns, often correlated with rocket and satellite observations. A 35 cm Mead telescope is situated at the station, but on a poor mounting. The station is at present situated in a number of small barracks in a valley somewhat disturbed by light from the settlement. This summer the construction of a new station further away from the settlement and higher up on a mountain, will start. Here a stable platform for the small telescope will be constructed and this may represent an opportunity to test SONG equipment on long continuous runs on the Northern Sky. At the moment we do not know how good the astroclimate is at this site, but at least for communication it is reached by daily flights from Oslo via Tromso. The optical station is administrated by UNIS, which is a satellite station for Norwegian Universities, offering one year courses in arctic related topics. All courses are given in English. This gives an opportunity to send a student for testing the astroclimate and the possibility of doing SONG related research

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Planet science possibilities with SONG - Uffe Gråe Jørgensen

Recently the first discovery of an Earth-like planet around another star was announced (Nature, January 26, 2006). It was identified from the microlensing effect it and its star had on a background star of magnitude I=14.25 (at baseline, and 11.25 at maximum magnification). Such bright stars could easily have been followed by modest sized SONG telescopes. Most microlensing events are, however, weaker, and it would therefore require special considerations to use SONG as an efficient microlensing follow-up exoplanet search facility. I will discuss the possibilities of using SONG for such a project, and compare the microlensing technique with other exoplanet search techniques.

I will also give a popular talk (in Danish) about exoplanets on Wednesday (22/3/06) at 19:30 in Aud 1, Kemisk Institut, Århus Universitet, arranged by Jydsk Selskab for Fysik og Kemi (www.chem.au.dk/~jydsk)

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Search for planets around G-type giants with EAPSNET - B. Sato

Planetary systems in massive stars (>1.5M_sun) convey important information on planet formation such as timescale of giant planet formation and dependence of properties of planets on host stars' mass. Little is known, however, about planetary systems in massive stars because precise radial velocity (RV) measurements are difficult when they are on the main-sequence due to the lack of appropriate abosorption lines in their spectra and thus few planets have been discovered around them so far. On the other hand, G-type giants, intermediate-mass (1.5~5M_sun) stars in evolved stages, are ideal targets because they have many sharp absorption lines for precise RV measurements. On these grounds, we are now carrying out an extensive Doppler planet searches of 500 G-type giants within the framework of EAPSNET (East-Asian Planet Search NETwork), an international collaboration between Korea, China and Japan. Each facility, BOAO (Korea), Xinglong (China), OAO (Japan), has a 2m class telescope, a high dispersion echelle spectrograph, and an iodine absorption cell for precise RV measurements. We here introduce the outline of our survey and collaboration in East Asia, and report the current status and future prospects.

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Chaos and planet-particle dynamics within the habitable zone of extrasolar planetary systems - T. Hinse

The orbital stability properties of hypothetic terrestrial planets (modelled as test particles) within the habitable zone of the stars HD4208 and HD70642 are investigated. The habitable zone for each system is determined from Kasting et al. (1993) and provides constrains on Kepler parameters within the (a,e)-space. Independent numerical simulations, using symplectic and interpolation methods, are used to study dynamical characteristics (i.e chaos and dynamical confinement within the system's orbital parameter phase space). The MEGNO indicator is used to measure the chaotic nature of the time evolution of Keplerian orbital parameters. Stability properties are inferred by directly considering the dynamics of 2 \times 10^{3} test particles. A dynamically "cold" (i.e e=0) distribution of particles with random mean anomalies is used as initial conditions throughout the habitable zone and the dynamics is followed for 10^{6} years. The presence of mean-motion resonances are capable in eccentricity excitation up to e=0.8 for the test particles located within the habitable zone. This kind of theoretical dynamical analysis will help future search projects for habitable terrestrial planets, by providing a mission targeting list of exosystems with a high confidence in harbouring terrestrial like planets on dynamically stable orbits confined within the habitable zone.


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Asteroseismology --- observations of solar-like oscillations - T. Bedding

I will review recent observations, both from the ground and from space, of solar-like oscillations. A lot of work is being done using high-precision Doppler measurements with 4-m class telescopes, using either iodine absorption or thorium-argon emission as the stable reference. The best results have come from two-site campaigns, although single-site observations are also being carried out. From space, the WIRE and MOST missions have detected oscillations using photometry. The duty cycle is much better than has be achieved from the ground but the signal-to-noise is poorer. I will summarize the results from both methods and try to extract some lessons for SONG.

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Asteroseismology in China - Jianning Fu

During the past decade great progress has been made in the field of asteroseismology in observational and theoretical research in China. The talk will review the most important results in asteroseismology made in China, in particular the involvements in multiple international observation networks, e.g. WET, STEPHI, and DSN, and the developments of the theoretical modeling codes for the main-sequence stars and the white dwarf stars. The prospects of future collaboration with the international colleagues in asteroseismology, including the potential in building the new observation networks with a site in China, is discussed.

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Asteroseismology --- the new hunting ground - Jørgen Christensen-Dalsgaard

Current asteroseismic observations are providing determinations of global stellar parameters and tantalizing hints of departures from the details of the model physics. Experience from the analyses of solar frequencies as well as model calculations shows that to proceed to a profound test of stellar internal physics we need substantially improved frequency determinations, requiring observations of individual stars covering many weeks. Also, a great deal can be gained from extending the observations of solar-like oscillations towards lower frequencies; here the mode lifetimes are generally longer, leading to an improved frequency precision, the uncertain near-surface effects on the frequencies are much reduced, and the frequencies show increased sensitivity to helium abundance in the convection zone. The resulting stringent requirements on the background noise are undoubtedly best met with Doppler-velocity observations such as proposed by SONG

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Main-sequence pulsators and their asteroseismic prospects with SONG - G. Handler

We briefly review the asteroseismic potential of main sequence pulsators more massive than the Sun, and we discuss their prospects and problems. We identify three classes among these pulsators that seem best suitable for SONG, the Delta Scuti, roAp and Beta Cephei stars, and we try to anticipate the asteroseismic progress to be made with SONG measurements of such stars

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Stellar activity and SONG - H. Korhonen

: Many stars with effective temperatures similar to the Sun's, or cooler, show strong solar-like magnetic activity. Cool stars have similar or deeper convective envelopes than the Sun, and sometimes they also have much faster rotation rates, especially if they are young or in close binary systems. Together, the convective motions and rapid rotation cause strong magnetic activity and very similar phenomena as observed in the Sun. SONG, with it's excellent time coverage will open doors to investigate stellar activity on short time scales and with continuous coverage. Also, most likely all cool stars show stellar activity at some level. This activity can cause variations in the spectral line profiles and thus affect the interpretation of the pulsation signal from these objects. In this talk I will focus on two aspects of stellar activity: 1) using SONG for investigating stellar activity, and 2) stellar activity as a possible noise source for the asteroseismology.

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On some properties of solar-like oscillations - G. Houdek

I intend to address two topics on solar-like oscillations: the first topic is a brief review on how amplitudes of stochastically excited oscillations depend on the height in the stellar atmosphere and how it relates to the measured surface Doppler signal. In my second topic I shall address some relations between stellar cycle amplitudes and acoustic oscillation properties.

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Envelope modelling of roAp stars in 3D - L. Freyhammer

The class of rapidly oscillating chemically peculiar A (roAp) stars is particularly promising for studying stellar interiors by means of asteroseismology. Still in their infancy, the techniques for studying these stars spectroscopically at high-dispersion, high-time resolution has already provided details on pulsations and abundance distributions seen in no other star but the sun. Two important roAp properties are chemical element stratification and an oblique magnetic axis: by spectroscopically measuring the doppler-shift amplitudes of chemical species, the depth of these elements in the star is derived; and by observing the star during whole rotation cycles, the full geometry of the global pulsation modes is established as well as the 3D distribution of chemical abundances. Spectroscopic studies of roAp stars are thus important for obtaining independent constraint on their atmospheric structure and abundance distribution and therefore also on tests of radiative diffusion calculations. The SONG network will be an invaluable tool to, eg., increase the sparse sample of known members of the class of roAp stars (currently 35 are known) and to resolve oscillations with close frequencies. We give examples of results from an on-going extensive spectroscopic study of roAp stars and discuss what would be required from a SONG network to optimally facilitate the solution of some major observational challenges in roAp studies.

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Precision radial velocities for giant stars - A. Quirrenbach


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GRB/SN science potentials for SONG - J. Fynbo


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The Hermes spectrograph - J. De Ridder


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An All Sky Extrasolar Planet Survey with New Generation Multiple Object Doppler Instruments at the Sloan Telescope and Its Follow-ups - Jian Ge

The All Sky Extrasolar Planet Survey is to monitor ~ 1 million nearby bright stars (V=8-13) for detecting tens of thousands of extrasolar planets between 2006-2020 using the new generation multiple object Dispersed Fixed-delay Interferometer Doppler instruments at the Sloan Digital Sky Survey (SDSS) 2.5-m telescope. Follow-ups with single object Doppler instruments at other telescopes can potentially increase the total number of detected planets by more than a factor of two. The initial results (including planet detection) from an on-going planet survey at the Kitt Peak 0.9-m Coude feed/2.1-m telescopes using a single object new generation high throughput Doppler instrument called Exoplanet Tracker will be presented. The early results from the commissioning of the first full-scale multiple object Doppler instrument called the W.M. Keck Exoplanet Tracker with 60 object capability will also be reported.

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BRITE-Constellation: a counterpart of SONG in space - W. W. Weiss

I intend to describe BRITE-Constellation, a network of 3 nanosatellites designed for space photometry of which 2 are already funded. We seek support for the third one. Science targets are the 300 brightest stars in the sky which dominantly are massive stars. Synergy with a spectroscopic ground based network, like SONG, is evident.

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High resolution spectrographs for SONG - P. Spano', G. Toso, F.M. Zerbi

Very high-resolution spectroscopy (R > 100,000) over a wide spectral range (>100 nm) can be optimally performed with echelle cross-dispersed spectrographs. We will present characteristics of different optical solutions: classical layouts like ESI, the Echellette Spectrograph and Imager at Keck, white-pupil configurations like UVES, the UV-Visual Echelle Spectrograph at VLT, or double-pass systems like MIKE, the Magellan Inamori Kyocera Echelle at Las Campanas Observatory or AVES, the Adaptive optics Visual Echelle Spectrograph at VLT. Some new materials, like Volume Phase Holographics Gratings (VPHG) will help in optmize performances. Scientific requirements and other constraints (space, weight, cost) will be taken into account in order to reduce the parameter space and find the best solution.

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Parasitic science with SONG - M. Andersen

The possibility of doing other science with SONG, using Low Light Level CCDs (3L-CCDs) on relatively simple additional instrumentation, will be discussed. It will be shown that a 1m telescope equipped a R=20000 3L-CCD echelle spectrograph, it is possible to a) determine the redshift of a 22nd magnitude Gamma-ray Burst afterglow in 1h and measure the radial velocity of a 18th mag star with an accuracy of 1 km/sec in 1 min. It will also be shown that equiping this telescope with a L3CCD direct camera, it will often be possible to acquire diffraction limited images (FWHM < 0.3 arcsec).

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