Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.eso.org/~mvandena/andres_poster.pdf Дата изменения: Mon Feb 9 14:08:41 2004 Дата индексирования: Mon Oct 1 23:45:23 2012 Кодировка: Поисковые слова: dust disk

Observational studies of gas in circumstellar disks around Young Stellar Objects
AndrИs CARMONA PhD student European Southern Observatory, Garching & Heidelberg University, H eidelberg, Germany Mario VAN DEN ANCKER, European Southern O bservatory, Garching, Germany Thomas HENNING, Max Planck Institute for Astronomy, Heidelberg. Germany

They are several fundamental questions concerning protoplanetary disks that await an observational answer
What is the disk density distribution as a function of the radius? What are the dynamics of the disk? What is the "real" dust to gas ratio? Time scal es. How fast does the disk di sappear? What is the mechanism of Giant Planet Formati on? core accretion? gravitational instabilities?


WHY IS THE GAS SO INTERESTING ?
99% of the mass of the disk is GAS direct measure of the disk mass direct estimation of radial density distribution Sharp lines kinematic information ! Giant Planets are gaseous connexion to exoplan ets formation
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Herbig Ae/Be stars !!!
Young age < 10 My Intermediate mass stars 2 ­ 10 M
Bigger circumstellar disks
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Fully radiative stars
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Disks are "passive"
Rad iate ma inly b y sta r light reproces sing





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Disks could be observationally studied using the GAS or the DUST However, until now the effort has been focused mainly on the study of the dust
Dust causes the bulk of infrared radiation and strong spectroscopic features in the Infrared

What is required to study the gas?
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The GOAL
Determine the disk's radial density distribution Obtain observational information on the gas dynamics Determine disk's life time Gaps ? Spiral Waves? Resonan ces?

Extremely High Spectral Resolu tion R~100 000 resolve the weak features of the gas resolve disk's velocity profile High Angular Resolution resolve the disk : 8 ­ 10 m class telescope Large Aperture obtain the required sensitivity
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W . Kle y. U . TЭbinge n

Important discoveries have been done from dust BUT crucial information is still missing
Dust does not provide kinematic information
S pectrospic dust features a re not sharp. G as to dust rati o in a di sk is e xp ec ted to change with t he di sk evolu tion. For est imati ng the disk's mass f ro m d ust ob se rvat ions models with hig h p ara meter u ncert ainti es are requ ired.
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This research is now possible thanks to the recent d evelopment of a new generation of high resolution spectrographs at ESO-VLT

This resea rch would provide cru cia l observational co nstraints abou t giant plan et for mation scenarios

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Method and Instrumentation
High Resolution In frared Spectroscop y a t ESO-VLT
VLT In frared S pect rometer An d Array Camera (in servi ce si nce 1 99 8 )

What kind of stars we need ?
Young stars ag e < 10 My Nearby, big and bright enough to be able to resolve the disk
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ISAAC

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Dust not allows a direct measure of the disk mass
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Waveleng th rang e 1 -5 µm up to m ed ium r es olutio n Rs ~ 3 00 0 Pixel size 0 .14 6 arcsec

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VL T Ima g er an d S pectrometer fo r mid Infra R ed (in serv ice soo n)
W av elen gth r an ge 8-1 3 an d 17 -2 4 µ m u p to h ig h r es olutio n R= 25 00 0 P ix el size 0.0 75 , 0 .1 27 , 0 .2 arcsec
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VISIR

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Gas studies are essential to complement dust studies

Hig h-R eso luti on IR Ech el le S pect rometer (in servi ce Oct 2 00 4)
Wavelen gth rang e 1 -5 µm up to h ig h resolution Rm ax = 10 0. 00 0 Pix el size 0 .1 ar csec Adap tive Op tics
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CRIRES

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