EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 395/2 Article
Free access article

Issue A&A
Volume 395, Number 2, November IV 2002
Page(s) 637 - 645
Section Diffuse matter in space
DOI http://dx.doi.org/10.1051/0004-6361:20020977



A&A 395, 637-645 (2002)
DOI: 10.1051/0004-6361:20020977

The complete far infrared spectroscopic survey of Herbig AeBe stars obtained by ISO-LWS

D. Lorenzetti1, T. Giannini1, B. Nisini1, M. Benedettini2, D. Elia3, L. Campeggio3 and F. Strafella3

1  INAF - Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio, Italy
    e-mail: teresa,bruni@coma.mporzio.astro.it
2  Istituto di Fisica Spazio Interplanetario - CNR Area Ricerca Tor Vergata, via Fosso del Cavaliere, 00133 Roma, Italy
    e-mail: milena@ifsi.rm.cnr.it
3  Università degli Studi di Lecce - Dipartimento di Fisica, via Arnesano, 73100 Lecce, Italy
    e-mail: eliad,campeggio,strafella@le.infn.it

(Received 17 May 2002 / Accepted 28 June 2002)

Abstract
The ISO-LWS archive has been systematically searched in order to obtain a complete far IR spectrophotometric survey of Herbig AeBe (HAEBE) stars. The investigated sample is constituted by 15 objects which, together with the 11 HAEBE we have published in two previous papers, represents about 25% of all the known HAEBE. This catalogue constitues an essential data-base in view of far IR forthcoming space missions (e.g. Herschel Space Observatory), whose scientific programs are now in the planning phase. The new sources are analysed following the same approach as in our previous papers and both differences and similarities are discussed in a coherent framework. The [OI] 63  $\mu$m and the [CII] 158  $\mu$m lines are observed in many of the investigated sources, while the [OI] 145  $\mu$m remains often undetected, due to its relative faintness. Molecular lines, in form of CO high- J rotational transitions are detected in only three cases and appear associated to local density peaks. A new class of ISO-LWS spectra of HAEBE emerges, constituted by objects without any detected gas feature either in emission or in absorption. Not unexpectedly, these HAEBE are isolated from molecular clouds and, as such, lack of the cold circumstellar material probed by far IR ionic and molecular transitions. By comparing line intensity ratios with model predictions we find that photodissociation caused by the stellar photons and active in a clumpy medium is likely the prevalent excitation mechanism for the far IR lines. Finally, an evolutionary trend is found according to which the contribution of the far IR line emission to the total emitted energy is less and less important with time.


Key words: stars: circumstellar matter -- stars: pre-main sequence -- infrared: ISM -- ISM: lines and bands -- infrared: stars

Offprint request: D. Lorenzetti, dloren@coma.mporzio.astro.it

SIMBAD Objects



© ESO 2002


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.