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)

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%)

MJUO location

Mt John University Observatory (MJUO)

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

MJUO 1.0-m telescope

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 profileseg 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

• FEROS – Chile

• HERCULES

– New Zealand

• 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?

← 16 Days →

←

6

km

 s-1

→

FIGARO and HRSP

• Same overall radial velocity variation

• HRSP has better internal precision

←

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

Nightly variations

← 3 hours →

← 1

km

 s-1

→

Seeing pulsation in spectroscopy

←

90

min

→

1

80

min

blo

cks

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