| 1. |
- Malbet, F., et al.
(författare)
-
High precision astrometry mission for the detection and characterization of nearby habitable planetary systems with the Nearby Earth Astrometric Telescope (NEAT)
- 2012
-
Ingår i: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 34:2, s. 385-413
-
Tidskriftsartikel (refereegranskat)abstract
- A complete census of planetary systems around a volume-limited sample of solar-type stars (FGK dwarfs) in the Solar neighborhood (d a parts per thousand currency signaEuro parts per thousand 15 pc) with uniform sensitivity down to Earth-mass planets within their Habitable Zones out to several AUs would be a major milestone in extrasolar planets astrophysics. This fundamental goal can be achieved with a mission concept such as NEAT-the Nearby Earth Astrometric Telescope. NEAT is designed to carry out space-borne extremely-high-precision astrometric measurements at the 0.05 mu as (1 sigma) accuracy level, sufficient to detect dynamical effects due to orbiting planets of mass even lower than Earth's around the nearest stars. Such a survey mission would provide the actual planetary masses and the full orbital geometry for all the components of the detected planetary systems down to the Earth-mass limit. The NEAT performance limits can be achieved by carrying out differential astrometry between the targets and a set of suitable reference stars in the field. The NEAT instrument design consists of an off-axis parabola single-mirror telescope (D = 1 m), a detector with a large field of view located 40 m away from the telescope and made of 8 small movable CCDs located around a fixed central CCD, and an interferometric calibration system monitoring dynamical Young's fringes originating from metrology fibers located at the primary mirror. The mission profile is driven by the fact that the two main modules of the payload, the telescope and the focal plane, must be located 40 m away leading to the choice of a formation flying option as the reference mission, and of a deployable boom option as an alternative choice. The proposed mission architecture relies on the use of two satellites, of about 700 kg each, operating at L2 for 5 years, flying in formation and offering a capability of more than 20,000 reconfigurations. The two satellites will be launched in a stacked configuration using a Soyuz ST launch vehicle. The NEAT primary science program will encompass an astrometric survey of our 200 closest F-, G- and K-type stellar neighbors, with an average of 50 visits each distributed over the nominal mission duration. The main survey operation will use approximately 70% of the mission lifetime. The remaining 30% of NEAT observing time might be allocated, for example, to improve the characterization of the architecture of selected planetary systems around nearby targets of specific interest (low-mass stars, young stars, etc.) discovered by Gaia, ground-based high-precision radial-velocity surveys, and other programs. With its exquisite, surgical astrometric precision, NEAT holds the promise to provide the first thorough census for Earth-mass planets around stars in the immediate vicinity of our Sun.
|
|
| 2. |
- Adamo, Angela, et al.
(författare)
-
Star Clusters Near and Far Tracing Star Formation Across Cosmic Time
- 2020
-
Ingår i: Space Science Reviews. - : Springer Science and Business Media LLC. - 0038-6308 .- 1572-9672. ; 216:4
-
Forskningsöversikt (refereegranskat)abstract
- Star clusters are fundamental units of stellar feedback and unique tracers of their host galactic properties. In this review, we will first focus on their constituents, i.e. detailed insight into their stellar populations and their surrounding ionised, warm, neutral, and molecular gas. We, then, move beyond the Local Group to review star cluster populations at various evolutionary stages, and in diverse galactic environmental conditions accessible in the local Universe. At high redshift, where conditions for cluster formation and evolution are more extreme, we are only able to observe the integrated light of a handful of objects that we believe will become globular clusters. We therefore discuss how numerical and analytical methods, informed by the observed properties of cluster populations in the local Universe, are used to develop sophisticated simulations potentially capable of disentangling the genetic map of galaxy formation and assembly that is carried by globular cluster populations.
|
|
| 3. |
- Stanke, T., et al.
(författare)
-
The APEX Large CO Heterodyne Orion Legacy Survey (ALCOHOLS): I. Survey overview
- 2022
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 658
-
Tidskriftsartikel (refereegranskat)abstract
- Context. The Orion molecular cloud complex harbours the nearest Giant Molecular Clouds (GMCs) and the nearest site of high-mass star formation. Its young star and protostar populations are thoroughly characterized. The region is therefore a prime target for the study of star formation. Aims. Here, we verify the performance of the SuperCAM 64 pixel heterodyne array on the Atacama Pathfinder Experiment (APEX). We give a descriptive overview of a set of wide-field CO(32) spectral line cubes obtained towards the Orion GMC complex, aimed at characterizing the dynamics and structure of the extended molecular gas in diverse regions of the clouds, ranging from very active sites of clustered star formation in Orion B to comparatively quiet regions in southern Orion A. In a future publication, we will characterize the full population of protostellar outflows and their feedback over an entire GMC. Methods. We present a 2.7 square degree (130 pc2) mapping survey in the 12CO(32) transition, obtained using SuperCAM on APEX at an angular resolution of 19 (7600 AU or 0.037 pc at a distance of 400 pc), covering the main sites of star formation in the Orion B cloud (L 1622, NGC 2071, NGC 2068, Ori B9, NGC 2024, and NGC 2023), and a large patch in the southern part of the L 1641 cloud in Orion A. Results. We describe CO integrated line emission and line moment maps and position-velocity diagrams for all survey fields and discuss a few sub-regions in some detail. Evidence for expanding bubbles is seen with lines splitting into double components, often in areas of optical nebulosities, most prominently in the NGC 2024 H II region, where we argue that the bulk of the molecular gas is in the foreground of the H II region. High CO(32)/CO(10) line ratios reveal warm CO along the western edge of the Orion B cloud in the NGC 2023 & NGC 2024 region facing the IC 434 H II region. We see multiple, well separated radial velocity cloud components towards several fields and propose that L 1641-S consists of a sequence of clouds at increasingly larger distances. We find a small, seemingly spherical cloud, which we term Cow Nebula globule, north of NGC 2071. We confirm that we can trace high velocity line wings out to the extremely high velocity regime in protostellar molecular outflows for the NGC 2071-IR outflow and the NGC 2024 CO jet, and identify the protostellar dust core FIR4 (rather than FIR5) as the true driving source of the NGC 2024 monopolar outflow.
|
|
