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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)
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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)
Outline • Mt John University Observatory • Location • HERCULES • Asteroseismology Programmes • Spectroscopic observations • Radial velocity measures • Line profile analysis • Specific project: HD49434 • Conclusions
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%)
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
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.
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).
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
Spectroscopic Observations • Binaries
Spectroscopy - line profiles eg Sct star FG Vir (left) line profile variations (right) grayscale phased difference from mean
Spectroscopy - line profile variations (left) Ca I 612.2 nm line profile (right) Cross correlation profiles
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)
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.
Specific project: HD 49434 • Ground-based, high-resolution echelle spectra of HD49434 • Dor star • CoRot target
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
Data used • HERCULES – New Zealand • FEROS – Chile • SOPHIE- France
Analysis: Radial velocities • Auto cross-correlation of non-telluric orders of HERCULES spectra • Initial results:Δ 6 km s-1 in 16 days binary? ←6 km s-1 → ←16 Days →
FIGARO and HRSP • Same overall radial velocity variation • HRSP has better internal precision
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 ←6 km s-1→ ←49 Days →
Nightly variations ← 1km s-1→ ←3 hours →
Seeing pulsation in spectroscopy 180 min blocks ←90 min → Bruntt et al. (2002) This work
Results • Frequencies of 5, 7 and 11 cycles-per-day Doradus frequencies Scuti frequencies
Conclusion • Binary? • Doradus star? • Scuti star? • Combination? • More observations of HD 49434 are needed + analysis of all MJUO data