university of canterbury people: karen pollard peter cottrell

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Coordinated observational campaigns for non-radially pulsating objects at Mt John Observatory (New Zealand) University of Canterbury people: Karen Pollard Peter Cottrell Duncan Wright (PhD, now post-doc at Royal Observatory of Belgium) Florian Maisonneuve (PhD student) Emily Brunsden (BSc (Hons)) Pam Kilmartin (MJUO observer)

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Coordinated observational campaigns for non-radially pulsating objects at Mt John Observatory (New Zealand). University of Canterbury people: Karen Pollard Peter Cottrell Duncan Wright (PhD, now post-doc at Royal Observatory of Belgium) Florian Maisonneuve (PhD student) - PowerPoint PPT Presentation

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Page 1: University of Canterbury people: Karen Pollard Peter Cottrell

Coordinated observational campaigns for non-radially pulsating objects at

Mt John Observatory (New Zealand) University of Canterbury people:

Karen Pollard

Peter Cottrell

Duncan Wright (PhD, now post-doc at Royal Observatory of Belgium)

Florian Maisonneuve (PhD student)

Emily Brunsden (BSc (Hons))

Pam Kilmartin (MJUO observer)

Page 2: University of Canterbury people: Karen Pollard Peter Cottrell

Outline• Mt John University Observatory

– Location– HERCULES

• Asteroseismology Programmes– Spectroscopic observations– Radial velocity measures– Line profile analysis – Specific project: HD49434

• Conclusions

Page 3: University of Canterbury people: Karen Pollard Peter Cottrell

MJUO location• S43°59.2' E170°27.9' and 1031m

above sea level• Mt John is located next to Lake

Tekapo, South Island, New Zealand • Four telescopes on site: two 0.6m,

1.0m McLellan and 1.8m MOA

• Good spectroscopic site (~50%), fair photometric site (~20%)

Page 4: University of Canterbury people: Karen Pollard Peter Cottrell

MJUO location

Page 5: University of Canterbury people: Karen Pollard Peter Cottrell

Mt John University Observatory (MJUO)

Page 6: University of Canterbury people: Karen Pollard Peter Cottrell
Page 7: University of Canterbury people: Karen Pollard Peter Cottrell
Page 8: University of Canterbury people: Karen Pollard Peter Cottrell

Mt John University Observatory (MJUO)

• Instrumentation for asteroseismology:– 1.0 m McLellan telescope– fibre-fed High Efficiency and Resolution Canterbury

University Large Echelle Spectrograph, HERCULES

Page 9: University of Canterbury people: Karen Pollard Peter Cottrell

MJUO 1.0-m telescope

Page 10: University of Canterbury people: Karen Pollard Peter Cottrell

HERCULES• R ~ 40,000 for 100 fibre or

~ 80,000 for 50 fibre • Gives S/N ~ 100 on a 6th mag object

in ~7 min with wavelength coverage from 3800-7500 Å (old CCD 1K x 1K)

• New CCD (2K x 2K) has complete wavelength coverage with similar quantum efficiency

• New fibre scrambler designed and funded. Installation late 2008. Will improve precision. Design also includes the potential to add an Iodine cell for further precision.

Page 11: University of Canterbury people: Karen Pollard Peter Cottrell

Hercules design and stability• Major elements of HERCULES are

fixed to an optical bench inside a cylindrical vacuum tank (4.3 x 1.2 m) where pressure maintained at 1 - 5 torr. The tank is situated in a thermally isolated and insulated room.

• RMS stability of 15 m s-1 over time spans of 4 to 5 years is being achieved.

• This is ideal for high-resolution, time-series asteroseismological studies of reasonably bright stars (V < 8).

Page 12: University of Canterbury people: Karen Pollard Peter Cottrell
Page 13: University of Canterbury people: Karen Pollard Peter Cottrell

Asteroseismology programmes

• In recent years we have initiated and contributed to a number of campaigns to study non-radially pulsating objects: mainly Sct, Dor, Cep stars

Page 14: University of Canterbury people: Karen Pollard Peter Cottrell

Spectroscopic Observations

• Binaries

Page 15: University of Canterbury people: Karen Pollard Peter Cottrell

Spectroscopy - line profileseg Sct star FG Vir

(left) line profile variations (right) grayscale phased

difference from mean

Page 16: University of Canterbury people: Karen Pollard Peter Cottrell

Spectroscopy - line profile variations

(left) Ca I 612.2 nm line profile

(right) Cross correlation profiles

Page 17: University of Canterbury people: Karen Pollard Peter Cottrell

Analysis Tools - Cross correlation

• Cross-correlate an object’s spectrum with a template of delta functions (at correct position and depth of each line) gives a high S/N representative line profile(valid for lines similarly distorted by the pulsation)

Page 18: University of Canterbury people: Karen Pollard Peter Cottrell

Line moments• The periodogram of the first moment (left) shows the periodicities

present in the Scuti star FG Vir, whilst the second moment (right) shows the non-axisymmetric modes (m≠ 0) that are present.

• The line moment technique is useful for Scuti stars where the main line profile variations are line asymmetries.

Page 19: University of Canterbury people: Karen Pollard Peter Cottrell

Specific project: HD 49434

• Ground-based, high-resolution echelle spectra of HD49434 Dor star– CoRot target

Page 20: University of Canterbury people: Karen Pollard Peter Cottrell

HD 49434• MJUO observations 1-18 Feb 2007

– observed by Pollard, Kilmartin– analysed by Emily Brunsden BSc (Hons)

project (with additional data at similar time from SOPHIE and FEROS, supplied by Ennio Poretti)

• Additional MJUO data: (reduced but not analysed)– 2007 Nov1-6, Nov 21 - Dec 02 with

occasional spectra 2007 Dec - 2008 Jan

Page 21: University of Canterbury people: Karen Pollard Peter Cottrell

Data used

• FEROS – Chile

• HERCULES

– New Zealand

• SOPHIE- France

Page 22: University of Canterbury people: Karen Pollard Peter Cottrell

Analysis: Radial velocities

• Auto cross-correlation of non-telluric orders of HERCULES spectra

• Initial results:Δ 6 km s-1 in 16 days

binary?

← 16 Days →

6

km

 s-1

Page 23: University of Canterbury people: Karen Pollard Peter Cottrell

FIGARO and HRSP

• Same overall radial velocity variation

• HRSP has better internal precision

Page 24: University of Canterbury people: Karen Pollard Peter Cottrell

6 k

m s

-1

← 49 Days →

Collated results• However, no

trend seen in FEROS or SOPHIE data

• Katrien, using single line analysis, finds no trend in HERCULES radial velocities, although larger scatter

Page 25: University of Canterbury people: Karen Pollard Peter Cottrell

Nightly variations

← 3 hours →

← 1

km

 s-1

Page 26: University of Canterbury people: Karen Pollard Peter Cottrell

Seeing pulsation in spectroscopy

90

min

1

80

min

blo

cks

Bruntt et al. (2002) This work

Page 27: University of Canterbury people: Karen Pollard Peter Cottrell

Results

• Frequencies of 5, 7 and 11 cycles-per-day

Doradus frequencies

Scuti frequencies

Page 28: University of Canterbury people: Karen Pollard Peter Cottrell

Conclusion

• Binary? Doradus star? Scuti star? • Combination?

• More observations of HD 49434 are needed + analysis of all MJUO data