Open clusters and associations in the Gaia era

Moraux, E.

doi:10.1051/eas/1680004

Cited by 30 publications

(12 citation statements)

References 175 publications

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“…The age of 1I/'Oumuamua is not known: a preencounter velocity that is close to those of some young stellar associations with a false alarm probability < 1% hints at a common origin and age of 100 Myr (Gaidos et al 2017;Feng & Jones 2018) but track-back simulations are limited by the precision of available stellar space motions, the completeness of catalogs of nearby young stars, and the rapid accumulation of positional uncertainty with reversed time (Zhang 2018). The Gaia mission will provide a far more complete and accurate inventory of nearby young associations and their dynamics (Moraux 2016), and perhaps resolution of this question. A young age would create a conundrum: The average age of stars in the Galactic disk is a few Gyr and if each of these also produced planetesimals in roughly equal numbers, the prior probability that the first object we discover is much younger is very low.…”

Section: Discussionmentioning

confidence: 99%

What and whence 1I/‘Oumuamua: a contact binary from the debris of a young planetary system?

Gaidos

2018

Monthly Notices of the Royal Astronomical Society

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The first confirmed interstellar interloper in our Solar System, 1I/'Oumuamua, is likely to be a minor body ejected from another star, but its brief flyby and faintness made it difficult to study. Two remarkable properties are its large (up to 2.5 mag) rotational variability and its motion relative to the Sun before encounter. The former suggests an extremely elongated shape (aspect ratio 10) and the latter an origin from the protoplanetary disk of a young star in a nearby association. Against expectations, it is also not comet-like. 1I/'Oumuamua's variability can also be explained if it is a contact binary composed of near-equilibrium ellipsoidal components and heterogeneous surfaces, i.e. brighter, dust-mantled inner-facing hemispheres and darker, dust-free outer-facing poles. Such shapes are a plausible outcome of radiation, tides and collisions in systems where planets are clearing planetesimal disks. The probability that 1I/'Oumuamua has the same motion as a young ( 100 Myr) stellar association by coincidence is < 1%. If it is young, its detection vs. more numerous, older counterparts could be explained as a selection effect due to darkening of surfaces by Galactic cosmic rays and loss of dust. 1I/'Oumuamua's apparent lack of ices can be explained if ejected rocky planetesimals are characteristically smaller and thus far more numerous than their icy counterparts: the Solar System may currently host several such objects captured by the combined gravity of Jupiter and the Sun.

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Section: Discussionmentioning

confidence: 99%

What and whence 1I/‘Oumuamua: a contact binary from the debris of a young planetary system?

Gaidos

2018

Monthly Notices of the Royal Astronomical Society

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“…Jaehnig et al (2017) claim that the time sampling of their observations make it more sensitive to the critical 10 2 −10 4 day period range where binary systems are wide enough to be disrupted by dynamical interaction over ∼100 Myr timescale in dense environments. However, this scenario is proposed for clusters with typical densities of ≈30 M pc −3 (at the core radius, Piskunov et al 2007) and may not be compatible with the typical densities of ≈0.01 stars pc −3 for loose associations such as those in the SACY sample (Moraux 2016).…”

Section: Sb Fraction Evolution With Agementioning

confidence: 91%

Search for associations containing young stars (SACY)

Zúñiga-Fernández

Bayo

Elliott

et al. 2020

A&A

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Context. Nearby young associations offer one of the best opportunities for a detailed study of the properties of young stellar and substellar objects thanks to their proximity (<200 pc) and age (∼5−150 Myr). Previous works have identified spectroscopic (<5 au) binaries, close (5−1000 au) visual binaries, and wide or extremely wide (1000−100 000 au) binaries in the young associations. In most of the previous analyses, single-lined spectroscopic binaries (SB1) were identified based on radial velocities variations. However, this apparent variation may also be caused by mechanisms unrelated to multiplicity. Aims. We seek to update the spectroscopy binary fraction of the Search for Associations Containing Young stars (SACY) sample, taking into consideration all possible biases in our identification of binary candidates, such as activity and rotation. Methods. Using high-resolution spectroscopic observations, we produced ∼1300 cross-correlation functions (CCFs) to disentangle the previously mentioned sources of contamination. The radial velocity values we obtained were cross-matched with the literature and then used to revise and update the spectroscopic binary (SB) fraction in each object of the SACY association. In order to better describe the CCF profile, we calculated a set of high-order cross-correlation features to determine the origin of the variations in radial velocities. Results. We identified 68 SB candidates from our sample of 410 objects. Our results hint that at the possibility that the youngest associations have a higher SB fraction. Specifically, we found sensitivity-corrected SB fractions of 22−11+15% for ϵ Cha, 31−14+16% for TW Hya and 32−8+9% for β Pictoris, in contrast to the five oldest associations we have sampled (∼35−125 Myr) which are ∼10% or lower. This result seems independent of the methodology used to asses membership to the associations. Conclusions. The new CCF analysis, radial velocity estimates, and SB candidates are particularly relevant for membership revision of targets in young stellar associations. These targets would be ideal candidates for follow-up campaigns using high-resolution techniques to confirm binarity, resolve orbits, and, ideally, calculate dynamical masses. Additionally, if the results on the SB fraction in the youngest associations were confirmed, it could hint at a non-universal multiplicity among SACY associations.

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“…More than 2000 open clusters are known today, most of them within a distance of ∼ 2 kpc from the Sun [128]. This is roughly 1% of the total population of over 10 5 open clusters expected in the Galaxy [170]. The Gaia mission is extending the census of open clusters, most of which are located at high Galactic latitudes with low interstellar extinction.…”

Section: Clustersmentioning

confidence: 99%

All-sky visible and near infrared space astrometry

et al. 2021

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The era of all-sky space astrometry began with the Hipparcos mission in 1989 and provided the first very accurate catalogue of apparent magnitudes, positions, parallaxes and proper motions of 120 000 bright stars at the milliarcsec (or milliarcsec per year) accuracy level. Hipparcos has now been superseded by the results of the Gaia mission. The second Gaia data release contained astrometric data for almost 1.7 billion sources with tens of microarcsec (or microarcsec per year) accuracy in a vast volume of the Milky Way and future data releases will further improve on this. Gaia has just completed its nominal 5-year mission (July 2019), but is expected to continue in operations for an extended period of an additional 5 years through to mid 2024. Its final catalogue to be released $\sim $ ∼ 2027, will provide astrometry for $\sim $ ∼ 2 billion sources, with astrometric precisions reaching 10 microarcsec. Why is accurate astrometry so important? The answer is that it provides fundamental data which underpin much of modern observational astronomy as will be detailed in this White Paper. All-sky visible and Near-InfraRed (NIR) astrometry with a wavelength cutoff in the K-band is not just focused on a single or small number of key science cases. Instead, it is extremely broad, answering key science questions in nearly every branch of astronomy while also providing a dense and accurate visible-NIR reference frame needed for future astronomy facilities.

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Open clusters and associations in the Gaia era

Cited by 30 publications

References 175 publications

What and whence 1I/‘Oumuamua: a contact binary from the debris of a young planetary system?

What and whence 1I/‘Oumuamua: a contact binary from the debris of a young planetary system?

Search for associations containing young stars (SACY)

All-sky visible and near infrared space astrometry

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