march 28th 2007 juliet datson, students' workshop brown dwarfs an introduction
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March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
Brown dwarfs Brown dwarfs
An introductionAn introduction
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
What are brown dwarfs?What are brown dwarfs?
No hydrogen burning, only deuteriumNo hydrogen burning, only deuteriumDefined by mass – problem of exact mass Defined by mass – problem of exact mass
measurementsmeasurementsOne test: Lithium testOne test: Lithium test
Stars soon deplete their lithium, it burns at Stars soon deplete their lithium, it burns at little lower temperatures than hydrogenlittle lower temperatures than hydrogen
If lithium is still there after a certain amount of If lithium is still there after a certain amount of time – no hydrogen burningtime – no hydrogen burning
M < 0.065 M(solar)M < 0.065 M(solar)
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
What are brown dwarfs?What are brown dwarfs?
Boundary between planet and brown Boundary between planet and brown dwarf:dwarf:No free floating planetNo free floating planet0.0013 M(solar) is deuterium burning limit0.0013 M(solar) is deuterium burning limit
Pressure through electron degeneracyPressure through electron degeneracy
Baryonic dark matter candidatesBaryonic dark matter candidates
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
Size comparisonSize comparison
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
Classification of brown dwarfsClassification of brown dwarfs
Spectral classes OBAFGKMSpectral classes OBAFGKMClass M: low mass starsClass M: low mass starsNew spectral characteristicsNew spectral characteristicsNeed for new classesNeed for new classesClass L: Disappearance of TiO and VOClass L: Disappearance of TiO and VOClass T: Methane linesClass T: Methane linesOther classes predictedOther classes predicted
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
SpectraSpectra
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
SpectraSpectra
Complicated “coming Complicated “coming and going” of spectral and going” of spectral lines due to lines due to condensing of condensing of materials at lower materials at lower temperaturestemperatures
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
Other interesting featuresOther interesting features
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
How do brown dwarfs form?How do brown dwarfs form?
Turbulent fragmentationTurbulent fragmentationVery low mass prestellar coresVery low mass prestellar cores
Disc fragmentationDisc fragmentationForming in the disc of another starForming in the disc of another star
EjectionEjectionRecently: binary disruption (paper by Recently: binary disruption (paper by
Goodwin and Whitworth 2007)Goodwin and Whitworth 2007)
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
Why do we want to find them?Why do we want to find them?
To fill the gap between planets and starsTo fill the gap between planets and starsTo fully understand evolution of the To fully understand evolution of the
universeuniverseTo prove their mass-rangeTo prove their mass-rangeTo someday be able to define the terms: To someday be able to define the terms:
planet, brown dwarf, star in all variationsplanet, brown dwarf, star in all variations
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
How do we find them?How do we find them?
Young, hot dwarfs in IRYoung, hot dwarfs in IRCompanions:Companions:
Radial velocity surveysRadial velocity surveysTransits Transits basically the same way, as planets, only basically the same way, as planets, only
easier, because they are usually bigger easier, because they are usually bigger Remnants of planet searchesRemnants of planet searches
Confirmation in spectraConfirmation in spectra
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
ImageImage
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
My work – brown dwarfs in taurusMy work – brown dwarfs in taurus
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
My workMy work
Imaging fields in Taurus – Calar Alto? Imaging fields in Taurus – Calar Alto? No, CFHT from the internetNo, CFHT from the internet
Choose possible brown dwarf candidatesChoose possible brown dwarf candidatesCollect spectra for confirmation (Calar Collect spectra for confirmation (Calar
Alto)Alto)A lot of data reduction with IDL and IRAFA lot of data reduction with IDL and IRAF
Great new finding!!!Great new finding!!!
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
Calar AltoCalar Alto
March 28th 2007March 28th 2007 Juliet Datson, students' workshopJuliet Datson, students' workshop
Thank you for your attention.Thank you for your attention.