Identification of young nearby runaway stars based on <i>Gaia</i> data and the lithium test<sup>†</sup>

Bischoff, Richard J.; Mugrauer, M.; Torres, Guillermo; Heyne, T.; Lux, Oliver; Munz, V.; Neuhäuser, R.; Hoffmann, Susanne M.; Trepanovski, Anja

doi:10.1002/asna.202013793

Cited by 6 publications

(13 citation statements)

References 46 publications

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“…GJ 182 (HIP 23200) is one of the youngest stars (e.g. Bischoff et al 2020b) and, given its distance of 24.38 ± 0.02 pc (Bailer-Jones et al 2018), there is no star known that is both younger and more nearby. Its age was estimated by Bischoff et al (2020b) to be ranging between 20 and 50 Myr, 14).…”

Section: Discussionmentioning

confidence: 99%

“…Bischoff et al 2020b) and, given its distance of 24.38 ± 0.02 pc (Bailer-Jones et al 2018), there is no star known that is both younger and more nearby. Its age was estimated by Bischoff et al (2020b) to be ranging between 20 and 50 Myr, 14). The determined age of the stars in the Hyades cluster is 750 ± 100 Myr according to Gagné et al (2018).…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, their declination angle had to be Dec > −14 • so that they can be observed at air masses X < 2.4 from Jena. As mentioned in Bischoff et al (2020b), in total 460 stars were identified that fulfill these conditions and 308 of them were already observed and published. However, the remaining list of 152 stars could be further shortened with a rough analysis by using data from Gaia DR2 and the catalog of Bailer-Jones et al (2018) to rule out most of the giants.…”

Section: Sample Selection Observations and Data Reductionmentioning

confidence: 94%

“…We measured the equivalent width via a direct integration of the line profiles in the reduced spectra by using the IRAF (Tody 1993) task splot as explained in Bischoff et al (2020b).…”

Section: (6708 å) Equivalent Width Measurements and Abundancesmentioning

confidence: 99%

“…Additionally, we searched for another youth indicator, namely, the absorption line of the lithium doublet at 6,708 Å based on Neuhäuser (1997), within our spectroscopic observing program for selected stars from the catalog by Tetzlaff et al. This observing program started in 2015 and the first results were already published in Bischoff et al (2020b). The remaining targets of this project are presented and discussed in this article.…”

Section: Introductionmentioning

confidence: 99%

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Identification of additional young nearby runaway stars based on Gaia data release 2 observations and the lithium test

Bischoff¹,

Mugrauer²,

Torres

et al. 2021

Astron Nachr

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Runaway stars are characterized by their remarkably high space velocities, and the study of their formation mechanisms has attracted considerable interest.Young, nearby runaway stars are the most favorable for identifying their place of origin, and for searching for possible associated objects such as neutron stars.Usually, the research field of runaway stars focuses on O-and B-type stars, because these objects are better detectable at larger distances than late-type stars. Early-type runaway stars have the advantage that they evolve faster and can therefore better be confirmed to be young. In contrast to this, the catalog of Young runaway stars within 3 kpc by Tetzlaff, N., Neuhäuser, R., & Hohle, M. M. (2011, MNRAS, 410(1), 190-200) contains also stars of spectral type A and later.The objects in this catalog were originally classified as young (≤ 50 Myr) runaway stars by using Hipparcos data to estimate the ages from their location in the Hertzsprung-Russell diagram and evolutionary models. In this article, we redetermine and/or constrain their ages not only by using the more precise second data release of the Gaia mission, but also by measuring the equivalent width of the lithium (6,708 Å) line, which is a youth indicator. Therefore, we searched for lithium absorption in the spectra of 51 target stars, taken at the University Observatory Jena between March and September 2020 with the Échelle spectrograph FLECHAS, and within additional TRES-spectra from the Fred L. Whipple Observatory. The main part of this campaign with its 308 reduced spectra, accessible at VizieR, was already published. In this work, which is the continuation and completion of the in 2015 initiated observing campaign, we found three additional young runaway star candidates.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Sample Selection Observations and Data Reductionmentioning

confidence: 94%

“…We measured the equivalent width via a direct integration of the line profiles in the reduced spectra by using the IRAF (Tody 1993) task splot as explained in Bischoff et al (2020b).…”

Section: (6708 å) Equivalent Width Measurements and Abundancesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Identification of additional young nearby runaway stars based on Gaia data release 2 observations and the lithium test

Bischoff¹,

Mugrauer²,

Torres

et al. 2021

Astron Nachr

Self Cite

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Stellar triples on the edge

Toonen

Boekholt

Zwart

2022

A&A

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Context. Hierarchical triple stars are ideal laboratories for studying the interplay between orbital dynamics and stellar evolution. Both mass loss from stellar winds and strong gravitational perturbations between the inner and outer orbit cooperate to destabilise triple systems. Aims. Our current understanding of the evolution of unstable triple systems is mainly built upon results from extensive binary-single scattering experiments. However, destabilised hierarchical triples cover a different region of phase space. Therefore, we aim to construct a comprehensive overview of the evolutionary pathways of destabilised triple-star systems. Methods. Starting from generic initial conditions, we evolved an extensive set of hierarchical triples using the code TRES, combining secular dynamics and stellar evolution. We detected those triples that destabilise due to stellar winds and/or gravitational perturbations. Their evolution was continued with a direct N-body integrator coupled to stellar evolution. Results. The majority of triples (54–69%) preserve their hierarchy throughout their evolution, which is in contradiction with the commonly adopted picture that unstable triples always experience a chaotic, democratic resonant interaction. The duration of the unstable phase was found to be longer than expected (103 − 4 crossing times, reaching up to millions), so that long-term stellar evolution effects cannot be neglected. The most probable outcome is dissolution of the triple into a single star and binary (42–45%). This occurs through the commonly known democratic channel, during which the initial hierarchy is lost and the lightest body usually escapes, but also through a hierarchical channel, during which the tertiary is ejected in a slingshot, independent of its mass. Collisions are common (13–24% of destabilised triples), and they mostly involve the two original inner binary components still on the main sequence (77–94%). This contradicts the idea that collisions with a giant during democratic encounters dominate (only 5–12%). Together with collisions in stable triples, we find that triple evolution is the dominant mechanism for stellar collisions in the Milky Way. Lastly, our simulations produce runaway and walk-away stars with speeds up to several tens of km/s, with a maximum of a few 100 km s−1. We suggest that destabilised triples can explain – or at least alleviate the tension behind – the origin of the observed (massive) runaway stars. Conclusions. A promising indicator for distinguishing triples that will follow the democratic or hierarchical route, is the relative inclination between the inner and outer orbits. Its influence can be summed up in two rules of thumb: (1) prograde triples tend to evolve towards hierarchical collisions and ejections, and (2) retrograde triples tend to evolve towards democratic encounters and a loss of initial hierarchy, unless the system is compact, which experience collision preferentially. The trends found in this work complement those found previously from binary-single scattering experiments, and together they will help to generalise and improve our understanding on the evolution of unstable triple systems of various origins.

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Constraining the initial conditions of NGC 2264 using ejected stars found in Gaia DR2

Schoettler

Parker

Bruijne

2021

Monthly Notices of the Royal Astronomical Society

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Fast, ejected stars have been found around several young star-forming regions, such as the Orion Nebula Cluster (ONC). These ejected stars can be used to constrain the initial density, spatial and kinematic substructure when compared to predictions from N-body simulations. We search for runaway and slower walkaway stars using Gaia DR2 within 100 pc of NGC 2264, which contains subclustered regions around higher-mass OB-stars (S Mon, IRS 1 and IRS 2). We find five runaways and nine walkaways that trace back to S Mon and six runaways and five walkaways that trace back to IRS 1/2 based on their 3D-kinematics. We compare these numbers to a range of N-body simulations with different initial conditions. The number of runaways/walkaways is consistent with initial conditions with a high initial stellar density (∼10 000 M⊙ pc−3), a high initial amount of spatial substructure and either a subvirial or virialised ratio for all subclusters. We also confirm the trajectories of our ejected stars using the data from Gaia EDR3, which reduces the number of runaways from IRS 1/2 from six to four but leaves the number of runaways from S Mon unchanged. The reduction in runaways is due to smaller uncertainties in the proper motion and changes in the parallax/distance estimate for these stars in Gaia EDR3. We find further runaway/walkaway candidates based on proper motion alone in Gaia DR2, which could increase these numbers once radial velocities are available. We also expect further changes in the candidate list with upcoming Gaia data releases.

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Identification of young nearby runaway stars based on Gaia data and the lithium test^†

Cited by 6 publications

References 46 publications

Identification of additional young nearby runaway stars based on Gaia data release 2 observations and the lithium test

Identification of additional young nearby runaway stars based on Gaia data release 2 observations and the lithium test

Stellar triples on the edge

Constraining the initial conditions of NGC 2264 using ejected stars found in Gaia DR2

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Identification of young nearby runaway stars based on Gaia data and the lithium test†

Cited by 6 publications

References 46 publications

Identification of additional young nearby runaway stars based on Gaia data release 2 observations and the lithium test

Identification of additional young nearby runaway stars based on Gaia data release 2 observations and the lithium test

Stellar triples on the edge

Constraining the initial conditions of NGC 2264 using ejected stars found in Gaia DR2

Contact Info

Product

Resources

About

Identification of young nearby runaway stars based on Gaia data and the lithium test^†