Although stellar oscillations have been observed for more than two centuries, the demands of asteroseismology require new observations of substantially higher precision. Two major techniques are reviewed: Doppler spectroscopy and photometry. Fundamental limitations are described using the sun as a representative stellar target. The current state of the art is limited by lack of light in the case of Doppler methods and by atmospheric noise in the case of photometry. Prospects for improvements in both of these techniques are good and we may expect someday to be able to detect solar-like oscillations of stars as faint as 10th magnitude.

This paper describes the new version of our instrument used for detection of stellar oscillations. It is planned to use it next year for observations of Procyon and α Can in order to confirm the results already obtained. Because the prototype used in these first attempts did not succeed to be photon noise limited, it has been significantly redesigned in order to improve the situation regarding every source of noise.

Interferometric spectrometry techniques for measuring stellar oscillations have been developed at Imperial College, resulting in two separate interferometers, the Michelson and the Fabry-Perot based instruments. They have both been used on large telescopes; the Michelson instrument to search for oscillations in solar-type stars and the Fabry-Perot instrument to measure oscillations in δScuti-type stars. So far there has been only marginal evidence for solar-type oscillations, including our observations of εCyg with ~1ms−1 precision. In order to increase the significance of future observations we are currently improving both instruments and aim to achieve a ten-fold increase in precision, i.e. ~10cms−1, by using up to 100 separate spectral lines simultaneously. Such an improvement will allow us to continue the search for solar-type oscillations.

The Precision CAlcium Photometer (PCAP) has been built with characteristics optimized for amplitude astroseismology. The instrument consists of two units: an on-telescope optical system that forms and stabilizes a stellar image onto a 200 micron optical fiber; and a spectrometer unit that accepts the light from the fiber and integrates the Calcium II H and K lines (3968.5 Å and 3933.7 Å), along with adjacent continuum regions, in a photon-counting mode. Some key system characteristics include active image stabilization, a 12-meter optical fiber with ~70% transmission at 3950 Å, and a thermally and mechanically stable spectrometer. A description of the instrument and of laboratory and on-telescope test runs are discussed below.

Space observations offer many advantages for helio- and asteroseismology, due principally to the absence in space of transparency fluctuations, image blurring, and absorption by the Earth's atmosphere, and to the possibility of long-term continuous observations by a single spaceborne instrument. Helioseismology from space has already shown that stars produce a measurable oscillation signal through photometric variations at the micromagnitude level; this leads to the near-term possibility of simple spaceborne instruments for both helio- and asteroseismology. For the Sun, where photon flux is not a serious problem, doppler analyzer instruments also show great promise. A number of space investigations in helio- and asteroseismology presently under definition or development are briefly discussed.

Details are given about the operation of a two station network and of a new semi-automatic station which has recently been added. Comparison is made with predicted duty cycles. A possible way of quantifying the sky quality is also given.

General purpose telescopes fail to provide a cost-effective means of obtaining photometric data for asteroseismology. A continuous observing run on a particular star is best suited to automatic operation with a dedicated photoelectric telescope. As optical requirements for on-axis photometry are less severe than those for imaging, low-cost light-weight mirrors permit a saving in the size and cost of mount and dome. A stiff mounting with a low moment of inertia permits rapid movement under computer control. Adoption of a permanently mounted photometer and the elimination of manual controls also leads to design and operating economies. Maintenance can be shared with other instruments and travel and subsistence requirements are minimised. Therefore remote operation of a network of automatic telescopes at good sites could provide high quality data at reasonable cost.

As a cornerstone of its long term plan for space science research, the European Space Agency (ESA) is developing the Solar Terrestrial Physics Programme that consists of two parts: one, the Solar and Heliospheric Observatory (SOHO) for the study of the solar internal structure and the physics of the solar corona and the solar wind, and another, CLUSTER, a series of four spacecraft flying in formation to study small scale plasma phenomena in several regions of the magnetosphere and in the near Earth solar wind. The feasibility of the missions was demonstrated in Phase A studies carried out by industrial consortia under the supervision of ESA (1,2). According to the current plans an announcement of opportunity calling for instrument proposals will be issued by ESA during the first quarter of 1987. It is foreseen that the spacecraft will be launched by the end of 1994.

We describe a stellar seismology photometric experiment which we have proposed to embark on-board the interplanetary vehicles belonging to the VESTA mission (France - USSR mission towards Mars and the asteroids belt, to be launched about 1994). The objective is to use the cruise time to obtain long, uninterrupted observations of the white light fluctuations in a few late-type stars, with a view to the detection of global non-radial modes at the level 10−5 to 10−6 mag. We have performed a design-study of the instrumentation, formed by a 5 cm spherical collector, working in two spectral bands 1500 A wide, with two photomultipliers as detectors. Advantages and difficulties of the system are briefly discussed.

A rationale and plan for using the Hubble Space Telescope to observe solar-like oscillations in stars is presented.

This review of the conference will necessarily consider the seismological data implications for only stellar astrophysics. While there are some aspects of this conference that interface with subjects like relativity, gravity, stellar systems, studies of chaos, etc., these will not be discussed here. What we are doing here is discussing the interiors of stars. We want to learn about their masses and composition structures. Pulsation periods can be used to measure stellar mean densities. Further details that seem accessible are the solar rotation speed versus depth and latitude and the structure of both solar and stellar atmospheres.

Most of the contributions at this conference dealt with the hard problems of our understanding oscillations of the sun. As we shall see in many cases, the problems in understanding the stars by observing their pulsation periods are even more difficult. Similarities and differences between helioseismology and asteroseismology will be a principal theme of this review.

Greetings! We who now salute you from the year 2986 are members of the species Homo tachyones, the first human generation to learn how to use the tachyon. Naturally, following this discovery, the immediate question arose, “To what great purpose shall we put this knowledge?” After much deliberation, we decided on the interesting experiment of communicating about some of our more puzzling archaeopsychological discoveries with the subjects of those discoveries themselves, back in the distant and hitherto inaccessible past.

Recent observations of the mysterious astronomical body IAU 123 indicate that the ‘Q’ueue value for astronomy symposia can approach 100–120, with very rapid growth and slow exponential decay. Number density fluctuations, with a frequency of 11.56 μHz and extreme phase coherence have been detected outside the main cafeteria. The long period and high ‘Q’ suggest that this may be represented by a g-mode of low radial order.

A stabilized Fabry-Perot etalon has been used to measure the low-level motions, with propagation velocities of order 0.01 cm s−1. Although this is well below the local Alfvén speed, there can still arise significant shock effects (e.g. upon discovery of liver loaf as the main course).

The observed cafeteria oscillation spectrum is still incomplete. For instance, if ice cream were offered at the end of the line, we would expect to detect the well-known ‘a la’-mode predicted by Baskin and Robbins.

We hope that future studies of astronomical Q's may lead to a better understanding of solar-type astronomers' resonant cavities.