Transcript Hungarian participation in COROT

Potential of regular spacings for mode
identification:
case of a CoRoT d Scuti star
Margit Paparó
Zs. Bognár, J.M. Benkő, D. Gandolfi, A. Moya, J.C. Suárez, Á. Sódor, M.
Hareter, E. Poretti, M. Auvergne, A. Baglin, W.W. Weiss and E.W. Guenther
Konkoly Observatory, MTA CSFK, Budapest, Hungary
CoRoT Week 11
19 – 22 March, 2013, Tenerife, Spain
Mode identification
• Cornerstone of asteroseismology
• Asymptotic regime: patterns exist (solar type oscillation and white
dwarfs
 d Scuti stars: outside of the asymptotic regime, no exact patterns
are expected
• Mode selection mechanism – few observed, more theoretically
predicted modes
• Ways of identification: multi-colour photometry and spectroscopy
• Space data: many targets, limited amount of observing time for
additional data
• Hope: some kind of regularity exists due to the long, continuous and
high precision measurements
How to pick a CoRoT d Scuti star up for
investigation
• Hungarian Asteroseimological Group (HAG) joined the CoRoT
preparatory work via the ESA PECS project with multi-colour
photometry (http://www.konkoly.hu/HAG/)
• Different kind of pulsating stars were observed: RR Lyrae, d Scuti, g
Doradus and b Cephei stars
• Photomeric characterisation of targets and discovery of new
variables on the exo-field were our main activity
• The most promising variable candidate was 21st on the field around
HD 292192 (http://www.konkoly.hu/HAG/research/sel21.html)
• Official CoRoT ID became 102749568 (Konkoly 21 is kept as
nickname)
Observations of CoRoT 102749568
discovered at Konkoly Observatory in 2005 by József Benkő
Photometry
CoRoT: LRa01
24 Oct. – 3 March, 2008
CoRoT team
Multi-colour follow-up
at Konkoly Observatory
11 nights at 2010/2011 and
2011/2012 winter season
Observer: Zsófia Bognár
Spectroscopy
AAOmega multi-object spectrograph at
3.9 m telescope of Australian Astr. Obs. at
2009
Davide Gandolfi and E. W. Guenther
Mercator+HERMES
in 2013, observer: Ádám Sódor
contributor: Markus Hareter
Fourier analyses of CoRoT data
We perfomed a
standard Fourier
analysis in white light
Fits are given with 3 and 67
frequencies. The pulsational
energy is concentrated in a
few modes
52 independent modes
were found above the
S/N=4 significance level
(Linear combination
modes were omitted)
Frequency spacing of 52 independent modes
0.84
0.2
0.66
2.2
2.7 (31.48 mHz)
- More than one radial period ratio were found in the early analyses
- A sequence of consecutive radial orders separated by the large
separation were expected
- We got very clean spacing diagram with some dominant peaks
- The values were used to prepare the echelle diagrams
Folded
Echelle diagrams – I. Can we use them in the nonasymptotic regime?
by 0.2 c/d (2.35 mHz)
Folded by 0.84 c/d (9.8 mHz)
Folded by 0.66 c/d (7.64 mHz)
- Blue circles are mostly the highest
amplitude modes
- Red points represent the lowest amplitude
modes of the 52 independent modes
No obvious, clear patterns exist
Echelle diagram – II. Can we use it for getting the large
separation in the non-asymptotic regime?
Folded by 2.20 c/d (25.46 mHz)
No clear patterns exist for the low
amplitude modes (red points). A few
points are arranged along curved
lines in both panels.
Folded by 2.72 c/d (31.48 mHz)
The blue circles are distributed along
three inclined „straight” lines in both
panels. The inclinations are different
for the different value of the possible
large separations.
Is there a different way to get more information
about the modes (both l and n values)?
A paper titled:
CoRoT 1027495568: mode identification of a d Scuti star based
on regular spacings
with the same co-authors as this presentation will be
submitted to A&A in a few weeks
- We constructed a different diagram to use all the regular
spacings of the highest amplitude modes
- Regularity helped the interpretation of the spacings up to
the identification of modes
- We used spectroscopy, multi-colour photometry and
modelling for confirmation
Conclusion on spacings
• Although we are out of the asymptotic regime,
quasi-equidistancies can be found among the
frequencies of space data.
• The potential of the mode identification based
only on the frequency regularities is highly
valuable.
• We have started a systematic search for
spacings in d Scuti, g Dor and hybrid stars
observed by CoRoT.
Period ratios – new observable
that space missions can serve for many stars
• Period ratios are the most precise values derived from the
frequencies
• Thousands of different kind of pulsating stars have list of increased
number of frequencies thanks to the space missions
• We may start a new way of investigation using the period ratios if
the theoretical calibration is going to be solved
• The period ratios of CoRoT 102749568 were used for independent
mode identification in the paper:
Frequency regularities in d Scuti stars
M. Paparó and J.M. Benkő
in ASP Conf. Ser., The 61B Fujihara Seminar: Progress in Physics of
Sun and Stars, A New Era in Helio- and Asteroseismology, ed. H.
Shibahashi & A.E. Lynas-Gray (ASP, San Fransisco), in press
copy request: [email protected]
Behaviour of the near radial period ratio region
Near radial period ratio of
102749568. Closely spaced
period ratios create vertical
lines due to grouping of
frequencies
Systematic search for 22 Scuti stars.
Vertical lines generally appears
a. e Cep, b. KIC 9700322, c. HD
50844, d. KIC 4840675 (fast rotator)
Mode identification based only on period ratios
Whole range of the period ratios for
102749568 and selected segments
for mode identification. The missing
frequencies exclude the quantum
numbers used for the segments.
Comparison of the distribution of period
ratios for 102749568 and some
randomly generated frequency sets (KS
test proves the difference).
Identification: 3-3-3-2 modes with 100-83-75-60 %. The real
identification was excluded only in one case. Theoretical
calibration is needed for a general use of peiod ratio
Thank you