idw – Informationsdienst Wissenschaft
Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
Using the new LUCI-1 instrument at the worlds largest telescope, the Large Binocular Telescope (LBT) in Arizona, astronomers from German institutes detected for the first time that the massive stars in the Galactic star forming region W3Main are not born simultaneously. This discovery has important consequences for our general understanding of the star formation process and the simple picture where stars are born in just a single event is under debate. Over the recent years evidence has been presented that it is more complex in most regions. From this result we now know that stars can form over a time span of several million years.
Massive stars, as massive as 10 to 100 times the sun, always form together in groups or clusters within dense clouds of dust and gas, so-called molecular clouds. One example of such an environment in our own galaxy, the Milky Way, is W3Main at a distance of 6000 light years. W3Main is part of a larger star forming region in the northern constellation Cassiopeia.
The assumption that the stars in such regions form simultaneously is being questioned for a long time and it could be possible that the first formed stars may initiate or at least affect the formation of the later generation of stars. The only way to figure out the actual history and the time span of star formation would be to accurately measure the ages of the massive stars inside.
Such observations are challenging, since massive stars form deeply embedded in molecular clouds, thus enshrouded in a dense and apparently impenetrable curtain of dust and gas. This makes their formation and first stages of their life invisible for telescopes working at optical wavelengths. Fortunately, observations at longer, near-infrared wavelengths lift the curtain and reveal the hidden stars by penetrating the dust.
The new LUCI-1 instrument – a multi-mode near-infrared spectro-imager at the LBT – is perfectly suited to study these young and recently formed massive stars and to try to measure their ages. For comparison, Figure 1 shows the LUCI-1 image of W3Main in the near-infrared (top left) and an image taken in visible light (top right). While the latter shows only a few stars, the LUCI-1 image, in contrast, reveals a populous group of young stars.
Images, however, only provide information about the brightness and color of stars and are, therefore, of limited use in determining stellar properties. Spectra, on the other hand, enable a much better characterization, since they are like stellar fingerprints. In a spectrum, stellar light is fanned out into its individual colors (wavelengths), as visible in a rainbow revealing a lot of spectral lines, characteristic of their chemical and physical condition. This allows a determination of its spectral type from which luminosity and temperature can accurately be derived. Comparison with models of stellar evolution results in a precise age estimate.
Getting spectra of a representative number of the distant and therefore faint stars in W3Main requires long observations to collect enough light, even with the largest telescopes. Now a group of scientists, led by Dr. Arjan Bik of the Max-Planck Institute for Astronomy in Heidelberg, could obtain high quality spectra of the 16 most massive stars in W3Main simultaneously (see Figure 2 for details) by using the infrared multi-object spectroscopy (MOS) mode of LUCI-1 at the LBT.
"For the first time we were able to derive ages of several massive stars inside W3Main and derive the time span over which the stars in W3Main are forming" said Dr. Arjan Bik, the leading author of the related scientific paper published in the January issue of the renowned Astrophysical Journal. "The oldest stars in the star forming region turn out to be already 2 million years old, while other stars are even younger and still forming and deeply embedded in their birth cocoons."
This result confirms that star formation in regions where massive stars form can be more complex than a single episode and stars can form over several million years. We now know that the stars in W3 main formed over a time span, starting 2 million years ago and continuing until today. This also suggests that the mutual interaction between the stars formed first and those still forming is a very important ingredient of the star formation process.
Contact
Dr. Arjan Bik
Phone: (+49|0) 6221 – 528 460
Email: abik@mpia.de
Prof. Dr. Thomas Henning
Phone: (+49|0) 6221 – 528 201
Email: henning@mpia.de
Dr. Klaus Jäger
Phone: (+49|0) 6221 – 528 379
Email: pr@mpia.de
Dr. Markus Pössel
Phone: (+49|0) 6221 – 528 261
Email: pr@mpia.de
all at the
Max Planck Institute for Astronomy
Königstuhl 17
69117 Heidelberg
http://www.mpia.de/Public/menu_q2e.php?Aktuelles/PR/2012/PR120216/PR_120216_en.h... - Online version of this press release (includes additional images and background information)
LUCI-1 image of W3Main in the near-infrared
Image: Bik et al., ApJ, 744, 87 2012
None
Merkmale dieser Pressemitteilung:
Journalisten, Lehrer/Schüler, Studierende, Wissenschaftler, jedermann
Physik / Astronomie
überregional
Forschungsergebnisse
Englisch
LUCI-1 image of W3Main in the near-infrared
Image: Bik et al., ApJ, 744, 87 2012
None
Sie können Suchbegriffe mit und, oder und / oder nicht verknüpfen, z. B. Philo nicht logie.
Verknüpfungen können Sie mit Klammern voneinander trennen, z. B. (Philo nicht logie) oder (Psycho und logie).
Zusammenhängende Worte werden als Wortgruppe gesucht, wenn Sie sie in Anführungsstriche setzen, z. B. „Bundesrepublik Deutschland“.
Die Erweiterte Suche können Sie auch nutzen, ohne Suchbegriffe einzugeben. Sie orientiert sich dann an den Kriterien, die Sie ausgewählt haben (z. B. nach dem Land oder dem Sachgebiet).
Haben Sie in einer Kategorie kein Kriterium ausgewählt, wird die gesamte Kategorie durchsucht (z.B. alle Sachgebiete oder alle Länder).
