Methane imaging of Pleiades T Dwarfs Sarah Casewell

T dwarfs in the Pleiades Why T dwarfs? Low mass end of star formation models Atmosphere models L-T transition Why the Pleiades? Best understood cluster in the night sky Valid Lithium age for the cluster Robust age for evolutionary models Talk about bds, why we study them and why the Pleiades

Survey area Numbered are WFCAM fields, letters are cfht – 2.5 square degree overlap.

I,I-Z CMD candidates Blue: Selected objects Cyan: Known members Red: DUSTY model Black: NextGen model Black is all I-Z objects from CFH12k. Black is nextgen, red, dusty. Blue are selected objects. Pale blue previoiuly identified cluster members used as a guide to the sequence.

Z,Z-J CMD candidates Red: PM candidates Cyan: PM members Blue: DUSTY model Black: NextGen model Z, Z-J blue open squares are the Z-J selected objects only. Black objects are selected objects from I, I-Z Red, objects that have been selected from this diagram. Blue objects are candidate members. Previously identified members used as a guide to the sequence have a circle around them. Black is nextgen, blue dusty

H,J-H CMD candidates Red: DUSTY model Black: NextGen model Blue: Moraux members Green: Bihain members Late L H, J-H nextgen black, red dusty, green bihain, blue estelle, red diamonds new points from z-j data only. Black points new data Early to mid T

J,J-K CMD candidates Red: DUSTY model Black: NextGen model Blue: Moraux members Green: Bihain members K, J-K. Point out what symbols are. Green Bihian, Blue Estelle, Red Bouvier, 4 black points new members – black line NEXTGEN, red is DUSTY. Point out that the onset of methane and clouds sinking causes the blueward sequence. Early T Late L

Methane Imaging How does it work? Describe spectra and methane

Negative results PLZJ 112 PLZJ 235 PLZJ721 Future work on the Pleiades project. Talk about disks around brown dwarfs PLZJ 112 PLZJ 235 PLZJ721

Colours Show tinney diagrams tinney et al., 2005, AJ, 130, 2326

Colours Show tinney diagrams tinney et al., 2005, AJ, 130, 2326

Colours Show tinney diagrams tinney et al., 2005, AJ, 130, 2326

Colours Isotherms at 800 1000 and 1500 K High gravity is diamond, Box is low 5.5 5.0 and 4.5 log g.

Colours Same as above but with models?

Colours Show same temp and grav model but different types? Burrows/cond ?

Colours Isotherms at 800 1000 and 1500 K High gravity is diamond, Box is low

Colours Isotherms at 800 1000 and 1500 K High gravity is diamond, Box is low

Colours Isotherms at 800 1000 and 1500 K High gravity is diamond, Box is low Despite the differences in colours – the models do look similar

Conclusions Used CFHT and UKIRT to discover 5 T dwarf candidates Methane images show 3 are not point sources Used COND and CLR models and filters to generate tracks COND are good for J-K, CLR for H-K Pleiades objects are on L-T transition Summarise what I/we did P. Dobbie, S. Hodgkin, E. Moraux, R. Jameson,  N. Hambly, J. Irwin, N Lodieu.