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Post Info TOPIC: NGC 1333-IRAS 4B
Blobrana


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NGC 1333 IRAS 4A/4B
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Title: APEX-CHAMP+ high-J CO observations of low-mass young stellar objects: III. NGC 1333 IRAS 4A/4B envelope, outflow and UV heating
Authors: Umut A. Yldz, Lars E. Kristensen, Ewine F. van Dishoeck, Arnaud Belloche, Tim A. van Kempen, Michiel R. Hogerheijde, Rolf Gusten, Nienke van der Marel

NGC 1333 IRAS 4A and IRAS 4B sources are among the best studied Stage 0 low-mass protostars which are driving prominent bipolar outflows. Most studies have so far concentrated on the colder parts (T<30K) of these regions. The aim is to characterize the warmer parts of the protostellar envelope in order to quantify the feedback of the protostars on their surroundings in terms of shocks, UV heating, photodissociation and outflow dispersal. Fully sampled large scale maps of the region were obtained; APEX-CHAMP+ was used for 12CO 6-5, 13CO 6-5 and [CI] 2-1, and JCMT-HARP-B for 12CO 3-2 emissions. Complementary Herschel-HIFI and ground-based lines of CO and its isotopologs, from 1-0 upto 10-9 (Eu/k 300K), are collected at the source positions. Radiative-transfer models of the dust and lines are used to determine temperatures and masses of the outflowing and UV-heated gas and infer the CO abundance structure. Broad CO emission line profiles trace entrained shocked gas along the outflow walls, with typical temperatures of ~100K. At other positions surrounding the outflow and the protostar, the 6-5 line profiles are narrow indicating UV excitation. The narrow 13CO 6-5 data directly reveal the UV heated gas distribution for the first time. The amount of UV-heated and outflowing gas are found to be comparable from the 12CO and 13CO 6-5 maps, implying that UV photons can affect the gas as much as the outflows. Weak [CI] emission throughout the region indicates a lack of CO dissociating photons. Modelling of the C18O lines indicates the necessity of a "drop" abundance profile throughout the envelope where the CO freezes out and is reloaded back into the gas phase, thus providing quantitative evidence for the CO ice evaporation zone around the protostars. The inner abundances are less than the canonical value of CO/H_2=2.7x10^-4, indicating some processing of CO into other species on the grains.

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Blobrana


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RE: NGC 1333-IRAS 4B
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L'eau est un ingrédient indispensable à la vie sur terre. La plus grande quantité d'eau des océans terrestres provient probablement d'un nuage interstellaire qui s'est effondré et à donné naissance à notre système solaire. L'une des questions fondamentales dans l'étude de nos origines est de comprendre comment et où l'eau s'est formée et la manière dont les molécules ont trouvé leur chemin à partir du nuage interstellaire primitif jusqu'aux planètes, comme la terre, il y a environ 4,5 billion d'années.
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Première localisation de l'eau dans un système planétaire

Pour la première fois, des astronomes ont pu localiser de l'eau dans un disque protoplanétaire autour d'une jeune étoile de type solaire. Ces disques, au sein desquels l'on pense que les planètes se forment, sont constitués de gaz et de poussières. Deux chercheurs de l'Université de Bonn, du Leyden Observatory et du Max Planck Institute for extraterrestrial Physics, viennent de détecter la présence d'eau autour de la jeune étoile NGC 1333 IRAS4B. Cette vapeur d'eau se situe à environ 25 unités astronomiques de l'étoile centrale, soit environ la distance Soleil-Neptune et sa masse est équivalente à cent fois celle de l'ensemble des océans terrestres. Cette découverte a été réalisée grâce à l'interféromètre du Plateau de Bure dans le Dévoluy, l'un des observatoires radiomillimétriques les plus sensibles au monde. Cet interféromètre est constitué de 6 antennes radio de 15 m de diamètreet est une des deux stations d'observation de l'Institut de RadioAstronomie Millimétrique  (IRAM : INSU-CNRS, MPG, IGN). Le deuxième observatoire est constitué d'une antenne radiomillimétrique de 30 m de diamètre situé sur le Pico Veleta en Espagne. Le siège de l'IRAM est à Grenoble. Article paru dans Astrophysical Journal 10/02/2010.
Source

Google Earth file (kmz)

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Blobrana


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NASA's Spitzer Space Telescope has revealed a dusty star system being soaked with a "steamy rain" of water vapour.
The water, pulled from gassy stellar leftovers into a dusty disk, provides what astronomers think is the first direct look at how the life-giving liquid makes its way into planets. The disk is the same sort of thing that forms around many stars and, in the case of our sun, was the seedbed for planet formation.
The amount of water in the newly observed disk is thought to equal more than five times that of all oceans on Earth.

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Blobrana


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IRAS 4B Image Overlay.kmz
Google Sky File

-- Edited by Blobrana at 15:27, 2008-01-12

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Blobrana


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IRAS 4B.kmz
Google Sky File

-- Edited by Blobrana at 15:27, 2008-01-12

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 NASA's Spitzer Space Telescope has detected enough water vapour to fill the oceans on Earth five times inside the collapsing nest of a forming star system. Astronomers say the water vapour is pouring down from the system's natal cloud and smacking into a dusty disk where planets are thought to form.
The observations provide the first direct look at how water, an essential ingredient for life as we know it, begins to make its way into planets, possibly even rocky ones like our own.

"For the first time, we are seeing water being delivered to the region where planets will most likely form" - Dan Watson of the University of Rochester, N.Y.

Watson is the lead author of a paper about this "steamy" young star system, appearing in the Aug. 30 issue of Nature.

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Object Name: NGC 1333-IRAS 4B
Object Type: protostar
Position (J2000): RA: 3 29 12 Dec: +31 13 08
Distance: 320 pc (1000 light-years)
Constellation: Pegasus

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