radial-velocity planet-search survey of stars with circumstellar disks
DESCRIPTION
Radial-velocity planet-search survey of stars with circumstellar disks. Patrick Weise Johny Setiawan, Ralf Launhardt, André Müller, Thomas Henning Max-Planck-Institute for Astronomy, Heidelberg. Overview. Why are young planets important? Are precise RV measurements possible? - PowerPoint PPT PresentationTRANSCRIPT
Radial-velocity planet-search survey of stars with circumstellar disks
Patrick Weise
Johny Setiawan, Ralf Launhardt, André Müller, Thomas Henning
Max-Planck-Institute for Astronomy, Heidelberg
OverviewOverview
Why are young planets important?Why are young planets important?
Are precise RV measurements possible?Are precise RV measurements possible?
MACS - A new Crosscorrelation toolMACS - A new Crosscorrelation tool
Stellar activity and its effects on RV Stellar activity and its effects on RV
measurementsmeasurements
First results from our surveyFirst results from our survey
P. Weise – RV survey of stars with circumstellar disks
Planets around young starsPlanets around young stars
What processes affect the formation and What processes affect the formation and evolution of planets?evolution of planets?
When and where do planets form?When and where do planets form? How do planets form?How do planets form?
P. Weise – RV survey of stars with circumstellar disks
Important questions:Important questions:
Can planets be detected in circumstellar disks?Can planets be detected in circumstellar disks? How long need planets to be formed?How long need planets to be formed?
Suitable targets?Suitable targets?
Young (accreating) stars with circumstellar disks Young (accreating) stars with circumstellar disks are usually slow rotators and precise RV is possibleare usually slow rotators and precise RV is possible
P. Weise – RV survey of stars with circumstellar disks
Are young stars suitable for Are young stars suitable for precise RV measurements?precise RV measurements?
Accuracy for BD comp.
Accuracy for planetary comp.FEROS long-term accuracy
RV measurementsRV measurements
P. Weise – RV survey of stars with circumstellar disks
Our survey consists of 580 starsOur survey consists of 580 stars
Selected by youthness (<300Myr), dwarf Selected by youthness (<300Myr), dwarf stars, single starsstars, single stars
RV measurements are obtained by RV measurements are obtained by crosscorrelating stellar spectra with theoretical crosscorrelating stellar spectra with theoretical templatestemplates
The crosscorrelation profile gives RV and vsini The crosscorrelation profile gives RV and vsini of the starof the star
Data reduction tools to crosscorrelate spectra of Data reduction tools to crosscorrelate spectra of very young stars do not existsvery young stars do not exists
We are currently developing a new toolWe are currently developing a new tool
Crosscorrelation toolCrosscorrelation tool
MACS is a new tool for crosscorrelating stellar MACS is a new tool for crosscorrelating stellar spectra with theoretical templatesspectra with theoretical templates
P. Weise – RV survey of stars with circumstellar disks
Stellar activityStellar activity
Stellar spectral line shapes are affected byStellar spectral line shapes are affected by
Cold and hot spots on the surfaceCold and hot spots on the surface GranulationGranulation Non-radial pulsationsNon-radial pulsations Stellar windsStellar winds
P. Weise – RV survey of stars with circumstellar disks
Effect on RVEffect on RV
Spots and stellar winds alter spectral line shapeSpots and stellar winds alter spectral line shape
P. Weise – RV survey of stars with circumstellar disks
Measurable by line Measurable by line bisector variationbisector variation
Line bisector varies Line bisector varies with RVwith RV
Huerta, 2007Huerta, 2007
Müller, 2008Müller, 2008
PhotometryPhotometry
Photometric data is needed to check for short-periodic Photometric data is needed to check for short-periodic variation due to stellar spots and to identify stellar variation due to stellar spots and to identify stellar rotation periodrotation period
P. Weise – RV survey of stars with circumstellar disks
Huerta, 2007Huerta, 2007
Signals due to stellar spots are quasi-periodic and Signals due to stellar spots are quasi-periodic and short-lived (for young stars)short-lived (for young stars)
NIR spectroscopyNIR spectroscopy
P. Weise – RV survey of stars with circumstellar disks
This is an effect of lowered contrast between spot This is an effect of lowered contrast between spot and photosphereand photosphere
Amplitude of RV signal decreases with Amplitude of RV signal decreases with wavelength when signal is due to spotswavelength when signal is due to spots
Observationally not Observationally not yet proven. First yet proven. First results are results are inconclusiveinconclusive
Observing strategyObserving strategy
More than 1 period has to be well sampledMore than 1 period has to be well sampled To verify that amplitude and period of the To verify that amplitude and period of the
signal are stable over timesignal are stable over time Stellar spots are short-lived and amplitude Stellar spots are short-lived and amplitude
changeschanges Several exposures in one night neededSeveral exposures in one night needed
To identify short-period stellar activity To identify short-period stellar activity jitterjitter
Rotational period from activity indicators Rotational period from activity indicators (for young stars (for young stars ~~2-4 days)2-4 days)
P. Weise – RV survey of stars with circumstellar disks
Analysis strategyAnalysis strategy
Analyse RV and Line ShapeAnalyse RV and Line Shape If Bisector does not correlate with RV:If Bisector does not correlate with RV:
Check other activity indicatorsCheck other activity indicators HHαα, CaII, NaI, HeI, Line depth ratio , CaII, NaI, HeI, Line depth ratio
FeI/VI, Veiling, photometric dataFeI/VI, Veiling, photometric data Check them for periodicityCheck them for periodicity
If stellar activity indicators show no periodicity If stellar activity indicators show no periodicity or other than RV measurementsor other than RV measurements
Obtain NIR spectroscopy dataObtain NIR spectroscopy data
P. Weise – RV survey of stars with circumstellar disks
Our SurveyOur Survey
Targetlist of 580 young (<600 Myr) starsTargetlist of 580 young (<600 Myr) stars 208 have been observed with FEROS and 208 have been observed with FEROS and
analysed for stellar parametersanalysed for stellar parameters 58 stars have multi-epoch data58 stars have multi-epoch data 27 stars show signs of 27 stars show signs of circumstellar disks and 8circumstellar disks and 8
are still accreatingare still accreating
P. Weise – RV survey of stars with circumstellar disks
First results from our surveyFirst results from our survey
P. Weise – RV survey of stars with circumstellar disks
208 stars have been observed208 stars have been observed
24 are RV stable24 are RV stable 184 show RV variation184 show RV variation
34 are SB34 are SB133 have vsini<30km/s133 have vsini<30km/s
Signal due to Signal due to
stellar activitystellar activity
88
Planetary comp.Planetary comp.
22
BD comp.BD comp.
44
58 with more data58 with more data
33 carefully analysed33 carefully analysed
First results from our surveyFirst results from our survey
RV variation due to stellar spotsRV variation due to stellar spots
P. Weise – RV survey of stars with circumstellar disks
K0V star K0V star vvsinsinii=26 km/s Age=5 Myr=26 km/s Age=5 Myr
First results from our surveyFirst results from our survey
Brown Dwarf candidatesBrown Dwarf candidates
P. Weise – RV survey of stars with circumstellar disks
Age: 5Myr MAge: 5Myr M**: 2 M: 2 Mʘʘ
P: 38 d mP: 38 d m22sini: 31 Msini: 31 Mjupjup
Age: 3-5Myr MAge: 3-5Myr M**: 2.5 M: 2.5 Mʘʘ
P: 39 d mP: 39 d m22sini: 41 Msini: 41 Mjupjup
First results from our surveyFirst results from our survey
Planetary candidatePlanetary candidate
P. Weise – RV survey of stars with circumstellar disks
Age: 10Myr MAge: 10Myr M**: 1-2 M: 1-2 Mʘʘ
P: 34 d mP: 34 d m22sini: 5-9 Msini: 5-9 Mjupjup
Age: 75Myr MAge: 75Myr M**: 0.9 M: 0.9 Mʘʘ
P: 92.7 d mP: 92.7 d m22sini: 4 Msini: 4 Mjupjup
SummarySummary
RV surveys of young stars are possible and very RV surveys of young stars are possible and very important for planet formation and early evolutionimportant for planet formation and early evolution
Stellar activity indicators have to be analysed very Stellar activity indicators have to be analysed very carefully carefully
To improve data reduction for young stars, we are To improve data reduction for young stars, we are currently developing a new crosscorrelation toolcurrently developing a new crosscorrelation tool
Our survey has just started to find potential Our survey has just started to find potential planetary host stars with age planetary host stars with age 10 Myr 10 Myr
NIR spectroscopy has to be obtained to verify NIR spectroscopy has to be obtained to verify planetary companionsplanetary companions
P. Weise – RV survey of stars with circumstellar disks