Jeune système stellaire en train de former des étoiles multiples
Pour la première fois, des astronomes ont vu un disque de poussière autour d’une jeune étoile qui se fragmente pour devenir un système stellaire multiple. Cette image est composée de nouvelles observations d’ALMA (Atacama Large Millimeter/submillimeter Array) au Chili et révèle le processus en pleine action!
Les étoiles se forment dans des nuages cosmiques de gas et de poussière, quand le rare matériel des nuages se comprime gravitationnellement pour former des noyaux plus denses qui attirent encore plus de matériel vers l’intérieur. Ce dernier forme un disque en rotation autour de la jeune étoile et se consomme lentement. À la fin la jeune étoile a accumulé suffisamment de masse pour atteindre la température et la pression nécessaires en son centre pour déclencher les réactions de fusion nucléaire.
Les étoiles sans compagnons - comme le Soleil - ne sont pas si communes comme on se l’imaginait. En fait, environ la moitié des étoiles de notre galaxie ont au moins un compagnon, et quelques-unes sont encore plus sociables! Des études précédentes ont montré que les étoiles dans les systèmes multiples tendent à être ou relativement proches, à une distance inférieure à 500 fois la distance Terre-Soleil (appelé unité astronomique UA), ou significativement plus distantes, plus de 1000 UA.
Etant donné ces différences notables, les scientifiques ont conclu qu’il y avait deux mécanismes principaux qui produisent les systèmes stellaires multiples - soit le nuage original se comprime de manière instable et se fragmente, chaque fragment produisant une nouvelle étoile, soit le disque en rotation autour d’une étoile existante se fragmente, en produisant le même résultat. Les systèmes avec des séparations plus grandes se sont probablement formés à travers le premier processus (comme l’ont suggéré de récentes études) et les systèmes plus serrés à travers le deuxième processus (bien que les preuves de ce processus soient limitées).
Les nouvelles observations d’ALMA ont apporté des preuves supplémentaires pour cette conclusion. Cette image montre le deuxième processus en action, comme dans le jeune système triple L1448 IRS3B. Le trio est encore enfoui profondément dans le nuage originel dans la constellation de Persée, à une distance de 750 années-lumière de la Terre, et se nourrit voracement du matériel du disque environnant. ALMA a montré que ce disque possédait une structure spirale, une caractéristique de l’instabilité gravitationnelle.
ALAM (Atacama Large Millimeter/submillimeter Array), un institut de recherche international en astronomie, est un partenariat international entre l’organisation pour la recherche astronomique dans l’hémisphère austral (ESO), National Science Foundation (NSF) et National Institutes of Natural Sciences (NINS) du Japon en coopération avec la république du Chili. ALMA est financé par ESO au nom des états membres, par la NSF en coopération avec National Research Council of Canada (NRC) et par National Science Council de Taiwan (NSC) et par NINS en coopération avec Academia Sinica (AS), Taiwan et Korea Astronomy and Space Science Institute (KASI).
Liens
Crédit:
ALMA (ESO/NAOJ/NRAO)/J.J. Tobin (University of Oklahoma/Leiden University)
À propos de l'image
| Identification: | potw1644a |
| Langage: | fr-be |
| Type: | Observation |
| Date de publication: | 31 octobre 2016 06:00 |
| Taille: | 1200 x 1204 px |
À propos de l'objet
| Nom: | [BC86b] LDN 1448 IRS 3B, L1448 IRS3B |
| Type: | Milky Way : Star : Evolutionary Stage : Protostar Milky Way : Star : Grouping : Multiple |
| Distance: | 750 années lumière |
| Constellation: | Aries |
Fonds d'écran
Coordinates
| Position (RA): | 3 25 36.36 |
| Position (Dec): | 30° 45' 14.92" |
| Field of view: | 0.07 x 0.07 arcminutes |
| Orientation: | North is -0.0° left of vertical |
Couleurs & filtres
| Domaine | Longueur d'onde | Télescope |
|---|---|---|
| Millimétrique | 1.5 mm | Atacama Large Millimeter/submillimeter Array |
Our use of Cookies
We use cookies that are essential for accessing our websites and using our services. We also use cookies to analyse, measure and improve our websites’ performance, to enable content sharing via social media and to display media content hosted on third-party platforms.
ESO Cookies Policy
The European Organisation for Astronomical Research in the Southern Hemisphere (ESO) is the pre-eminent intergovernmental science and technology organisation in astronomy. It carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities for astronomy.
This Cookies Policy is intended to provide clarity by outlining the cookies used on the ESO public websites, their functions, the options you have for controlling them, and the ways you can contact us for additional details.
What are cookies?
Cookies are small pieces of data stored on your device by websites you visit. They serve various purposes, such as remembering login credentials and preferences and enhance your browsing experience.
Categories of cookies we use
Essential cookies (always active): These cookies are strictly necessary for the proper functioning of our website. Without these cookies, the website cannot operate correctly, and certain services, such as logging in or accessing secure areas, may not be available; because they are essential for the website’s operation, they cannot be disabled.
Functional Cookies: These cookies enhance your browsing experience by enabling additional features and personalization, such as remembering your preferences and settings. While not strictly necessary for the website to function, they improve usability and convenience; these cookies are only placed if you provide your consent.
Analytics cookies: These cookies collect information about how visitors interact with our website, such as which pages are visited most often and how users navigate the site. This data helps us improve website performance, optimize content, and enhance the user experience; these cookies are only placed if you provide your consent. We use the following analytics cookies.
Matomo Cookies:
This website uses Matomo (formerly Piwik), an open source software which enables the statistical analysis of website visits. Matomo uses cookies (text files) which are saved on your computer and which allow us to analyze how you use our website. The website user information generated by the cookies will only be saved on the servers of our IT Department. We use this information to analyze www.eso.org visits and to prepare reports on website activities. These data will not be disclosed to third parties.
On behalf of ESO, Matomo will use this information for the purpose of evaluating your use of the website, compiling reports on website activity and providing other services relating to website activity and internet usage.
Matomo cookies settings:
Additional Third-party cookies on ESO websites: some of our pages display content from external providers, e.g. YouTube.
Such third-party services are outside of ESO control and may, at any time, change their terms of service, use of cookies, etc.
YouTube: Some videos on the ESO website are embedded from ESO’s official YouTube channel. We have enabled YouTube’s privacy-enhanced mode, meaning that no cookies are set unless the user actively clicks on the video to play it. Additionally, in this mode, YouTube does not store any personally identifiable cookie data for embedded video playbacks. For more details, please refer to YouTube’s embedding videos information page.
Cookies can also be classified based on the following elements.
Regarding the domain, there are:
- First-party cookies, set by the website you are currently visiting. They are stored by the same domain that you are browsing and are used to enhance your experience on that site;
- Third-party cookies, set by a domain other than the one you are currently visiting.
As for their duration, cookies can be:
- Browser-session cookies, which are deleted when the user closes the browser;
- Stored cookies, which stay on the user's device for a predetermined period of time.
How to manage cookies
Cookie settings: You can modify your cookie choices for the ESO webpages at any time by clicking on the link Cookie settings at the bottom of any page.
In your browser: If you wish to delete cookies or instruct your browser to delete or block cookies by default, please visit the help pages of your browser:
Please be aware that if you delete or decline cookies, certain functionalities of our website may be not be available and your browsing experience may be affected.
You can set most browsers to prevent any cookies being placed on your device, but you may then have to manually adjust some preferences every time you visit a site/page. And some services and functionalities may not work properly at all (e.g. profile logging-in, shop check out).
Updates to the ESO Cookies Policy
The ESO Cookies Policy may be subject to future updates, which will be made available on this page.
Additional information
For any queries related to cookies, please contact: pdprATesoDOTorg.
As ESO public webpages are managed by our Department of Communication, your questions will be dealt with the support of the said Department.