Phoebus group

Key takeaways

Phoebus group belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Phoebus group to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Phoebus group from memory before moving on to harder problems.

Reference excerpt

The Phoebus group is an international team of European, Japanese and American scientists aiming at detecting the solar g modes. As of October 5, 2009, the group has finally produced a review summarising the work performed over the past 12 years.

Scientific Rationale Since the beginnings of global helioseismology in the late 1970s, the detection of g modes has been the quest for the Grail. The detection of g modes would be key to the understanding of the internal structure and dynamics of the solar core, as much as the p modes are key to that of the structure of the radiative and convective zones. The impact of g-mode detection would be so large that we could expect a wealth of information to be returned. The structure and dynamics of the energy-generating core will be seen, analyzed and understood. The hydrostatic structure of the core, in particular its deepest lying layers, will be uncovered to a far higher level of accuracy and precision; while it will be possible to infer the rotational characteristics of the core, characteristics that at present we are unable to uncover, to a satisfactory level of precision, with the current p-mode data. This quest was a major driver in the design of very precise and quiet instrumentation harboured by spacecraft such as the Solar and Heliospheric Observatory (SoHO. Aboard SOHO, there are three instruments dedicated to helioseismology all aiming at detecting g modes. A few years after the launch of SoHO in end 1995, it was realized that g modes would not be easily detected.

Sequence of events In 1997, a consortium of helioseismologists was formed with the simple goal of detecting g modes. Helioseismologists belonging to the SOHO consortia and to ground-based networks were teaming together for that goal. This consortium of helioseismologists was named the Phoebus group after Gaston Phoebus, Comte de Foix, who wrote a book about hunting, hoping thereby to 'catch' a few g modes. The work focused on data analysis of SOHO instruments (VIRGO, MDI) and ground-based networks (BiSON, Global Oscillations Network Group); on probability and statistics; and on theoretical model prediction of g-mode amplitudes and frequencies. The group met at ESTEC, Noordwijk (The Netherlands) during a series of five workshops that were held on 3–7 November 1997 (1st), on 26–30 October 1998 (2nd), on 25–29 October 1999 (3rd), on 7–11 June 2001 (4th), on 17–21 June 2002 (5th). Following the move of Thierry Appourchaux to the Institut d'Astrophysique Spatiale, the workshop were organized at ISSI under the auspices of Vittorio Manno and Roger-Maurice Bonnet. The group then met in Bern on 31 October - 4 November 2005 (6th), on 27–31 March 2006 (7th) (in Fréjus) and on 23–24 April 2007 (8th).

Current Membership Following, different interests in the search, a few members of the original group departed and were replaced. A major change occurred in 2004 with the inclusion of several members of the GOLF consortium. As of 2009, the members are as follows:

Past Membership In the life of the group the following members timely contributed:

Referred articles Appourchaux, T.; Pallé, P. L. (2013), "The History of the g-mode Quest", in K. Jain; S.C. Tripathy; F. Hill; J.W. Leibacher; A.A. Pevtsov (eds.), Fifty Years of Seismology of the Sun and Stars. Proceedings of a Workshop held 6–10 May, ASP Conference Proceedings, vol. 478, Astronomical Society of the Pacific, p. 125, arXiv:1309.3835, Bibcode:2013ASPC..478..125A Appourchaux, T.; Belkacem, K.; Broomhall, A.-M.; Chaplin, W. J.; Gough, D. O.; Houdek, G.; Provost, J.; Baudin, F.; Boumier, P.; Elsworth, Y.; García, R. A.; Andersen, B. N.; Finsterle, W.; Fröhlich, C.; Gabriel, A.; Grec, G.; Jiménez, A.; Kosovichev, A.; Sekii, T.; Toutain, T.; Turck-Chièze, S. (2010), "The quest for the solar g modes", Astronomy and Astrophysics Review, 18 (1–2): 197–277, arXiv:0910.0848, Bibcode:2010A&ARv..18..197A, doi:10.1007/s00159-009-0027-z Appourchaux, T.; Fröhlich, C.; Andersen, B.; Berthomieu, G.; Chaplin, W. J.; Elsworth, Y.; Finsterle, W.; Gough, D. O.; Hoeksema, J. T.; Isaak, G. R.; Kosovichev, A. G.; Provost, J.; Scherrer, P. H.; Sekii, T.; Toutain, T. (2000), "Observational Upper Limits to Low-Degree Solar g-Modes", Astrophysical Journal, 538 (1): 401–414, Bibcode:2000ApJ...538..401A, doi:10.1086/309124 Gabriel, A. H.; Baudin, F.; Boumier, P.; García, R. A.; Turck-Chièze, S.; Appourchaux, T.; Bertello, L.; Berthomieu, G.; Charra, J.; Gough, D. O.; Pallé, P. L.; Provost, J.; Renaud, C.; Robillot, J.-M.; Roca, Cortés T.; Thiery, S.; Ulrich, R. K. (2002), "A search for solar g modes in the GOLF data", Astronomy and Astrophysics, 390 (3): 1119, Bibcode:2002A&A...390.1119G, doi:10.1051/0004-6361:20020695 García, R. A.; Turck-Chièze, S.; Jiménez-Reyes, S. J.; Ballot, J.; Pallé, P. L.; Eff-Darwich, A.; Mathur, S.; Provost, J. (2007), "Tracking Solar Gravity Modes: The Dynamics of the Solar Core", Science, 316 (5831): 1591–1593, Bibcode:2007Sci...316.1591G, doi:10.1126/science.1140598, PMID 17478682 Turck-Chiéze, S.; García, R. A.; Couvidat, S.; Ulrich, R. K.; Bertello, L.; Varadi, F.; Kosovichev, A. G.; Gabriel, A. H.; Berthomieu, G.; Brun, A. S.; Lopes, I.; Palléé, P.; Provost, J.; Robillot, J. M.; Roca, Cortés T. (2004), "Looking for Gravity-Mode Multiplets with the GOLF Experiment aboard SOHO", Astrophysical Journal, 604 (1): 455–468, Bibcode:2004ApJ...604..455T, CiteSeerX 10.1.1.330.4074, doi:10.1086/381743 {{citation}}: Cite uses deprecated parameter |citeseerx= (help) Wachter, R.; Schou, J.; Kosovichev, A. G.; Scherrer, P. H. (2003), "Optimal Masks for Solar g-Mode Detection", Astrophysical Journal, 588 (2): 1199, Bibcode:2003ApJ...588.1199W, doi:10.1086/374302

References

External links The Phoebus page at IAS The Phoebus page at ISSI

Worked examples

Example 1 — a first encounter with Phoebus group

Start with the simplest possible case. Write down what Phoebus group claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Phoebus group before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Phoebus group ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Phoebus group

In research: Phoebus group appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Phoebus group in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Phoebus group is common in secondary-school and first-year university syllabi. It links to neighbouring topics Sun, so understanding it makes those chapters shorter.
In everyday life: Look for Phoebus group outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Phoebus group in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Phoebus group means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Phoebus group out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Phoebus group in simple terms?

The Phoebus group is an international team of European, Japanese and American scientists aiming at detecting the solar g modes. As of October 5, 2009, the group has finally produced a review summarising the work performed over the past 12 years.

Why does Phoebus group matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Phoebus group?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Phoebus group.