White dwarf-open cluster associations based on <i>Gaia</i> DR2

Prišegen, Michal; Piecka, Martin; Faltová, N.; Kajan, Michal; Paunzen, E.

doi:10.1051/0004-6361/202039276

Cited by 14 publications

(6 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the age of the cluster has been determined to be 400 Myrs (Bossini et al 2019), which is higher than our cut-off age. In addition, it has been found to host white dwarfs (Prišegen et al 2021), cooling times seem to be consistent with the isochrone age. According to its low space velocity the star is a walkaway.…”

Section: Hip 49934supporting

confidence: 64%

The origin of early-type runaway stars from open clusters

Bhat

Irrgang

Heber

2022

A&A

View full text Add to dashboard Cite

Runaway stars are ejected from their place of birth in the Galactic disk, with some young B-type runaways found several tens of kiloparsecs from the plane traveling at speeds beyond the escape velocity, which calls for violent ejection processes. Young open clusters are a likely place of origin, and ejection may be either through N-body interactions or in binary supernova explosions. The most energetic events may require dynamical interaction with massive black holes. The excellent quality of Gaia astrometry opens up the path to study the kinematics of young runaway stars to such a high precision that the place of origin in open stellar clusters can be identified uniquely even when the star is a few kiloparsecs away. We developed an efficient minimization method to calculate whether two or more objects may come from the same place, which we tested against samples of Orion runaways. Our fitting procedure was then used to calculate trajectories for known runaway stars, which have previously been studied from Hipparcos astrometry as well as known open clusters. For runaways in our sample we used Gaia data and updated radial velocities, and found that only half of the sample could be classified as runaways. The other half of the sample moves so slowly (<30 km s −1 ) that they have to be considered as walkaway stars. Most of the latter stars turned out to be binaries. We identified parent clusters for runaways based on their trajectories. We then used cluster age and flight time of the stars to investigate whether the ejection was likely due to a binary supernova or due to a dynamical ejection. In particular we show that the classical runaways AE Aurigae and µ Columbae might not have originated together, with µ Columbae having an earlier ejection from Collinder 69, a cluster near the ONC. The second sample investigated comprises a set of distant runaway B stars in the halo which have been studied carefully by quantitative spectral analyses. We are able to identify candidate parent clusters for at least four stars including the hyper-runaway candidate HIP 60350. The ejection events had to be very violent, ejecting stars at velocities as large as 150 to 400 km s −1 .

show abstract

Section: Hip 49934supporting

confidence: 64%

The origin of early-type runaway stars from open clusters

Bhat

Irrgang

Heber

2022

A&A

View full text Add to dashboard Cite

show abstract

“…We note that in the late stages of preparation of this manuscript, a related survey appeared on the archives (Prišegen et al 2020) that carried out a similarly motivated search for cluster WDs. Aside from some differences in methodology and scope, one important difference between our search and that one is that we have verified many of our best candidates with spectra, a critical component in establishing the properties of candidate cluster WDs.…”

Section: Determining Cluster Parametersmentioning

confidence: 99%

Massive White Dwarfs in Young Star Clusters

Richer

Caiazzo²,

Du³

et al. 2021

ApJ

View full text Add to dashboard Cite

We have carried out a search for massive white dwarfs (WDs) in the direction of young open star clusters using the Gaia DR2 database. The aim of this survey was (1) to provide robust data for new and previously known high-mass WDs regarding cluster membership, (2) to highlight WDs previously included in the initial final mass relation (IFMR) that are unlikely members of their respective clusters according to Gaia astrometry, and (3) to select an unequivocal WD sample that could then be compared with the host clusters' turnoff masses. All promising WD candidates in each cluster color-magnitude diagram were followed up with spectroscopy from Gemini in order to determine whether they were indeed WDs and derive their masses, temperatures, and ages. In order to be considered cluster members, white dwarfs were required to (1) have proper motions and parallaxes within 2σ, 3σ, or 4σ of those of their potential parent cluster based on how contaminated the field was in their region of the sky, (2) have a cooling age that was less than the cluster age, and (3) have a mass that was broadly consistent with the IFMR. A number of WDs included in current versions of the IFMR turned out to be nonmembers, and a number of apparent members, based on Gaia's astrometric data alone, were rejected, as their mass and/or cooling times were incompatible with cluster membership. In this way, we developed a highly selected IFMR sample for high-mass WDs that, surprisingly, contained no precursor masses significantly in excess of ∼ 6 M e .

show abstract

“…Because the ZTF survey also targets the Galactic disk, we have searched for possible open cluster members among our sample stars following the approach presented in Prišegen et al (2021).…”

Section: Stars In Open Cluster Fieldsmentioning

confidence: 99%

A case study of ACV variables discovered in the Zwicky Transient Facility survey

Faltová

Kallova

Prišegen

et al. 2021

A&A

Self Cite

View full text Add to dashboard Cite

Context. Magnetic chemically peculiar (mCP) stars exhibit complex atmospheres that allow the investigation of the interplay of atomic diffusion, magnetic fields, and stellar rotation. A non-uniform surface distribution of chemical elements and the non-alignment of the rotational and magnetic axes result in the variability of several observables. Photometrically variable mCP stars are referred to as α 2 Canum Venaticorum (ACV) variables. Aims. The present work presents a case study of known variables from the Zwicky Transient Facility (ZTF) survey, with the aim of investigating the survey's suitability for the detection and study of new ACV variables. Methods. Using suitable selection criteria based on the known characteristics of ACV variables, candidate ACV stars were selected from the ZTF Catalog of Periodic Variable Stars. All light curves were inspected in detail to select the most promising candidates. Where available, low-resolution spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) were employed to classify the stars on the MK system and confirm their status as mCP stars. Results. We have identified 86 new promising ACV star candidates. Fifteen of these stars have LAMOST spectra available that, in all cases, confirm them as classical mCP stars, which highlights the viability of our approach. We present astrophysical parameters for all sample stars that can be sorted into four subgroups characterized by distinct light curve shapes. Anti-phase variations in different photometric passbands, in particular, is a unique characteristic of a subset of ACV stars readily usable for their identification. The availability of data in three different passbands (g, r, and i) is a major advantage of the ZTF survey. Conclusions. On the basis of our experience with other photometric surveys and the analysis of light curves, we conclude that the ZTF is well suited to the search for, and the analysis of, ACV variables that are not considered in the available ZTF variable star catalogs. Further work will focus on the development and refinement of a search algorithm to correctly identify these stars in ZTF data and, subsequently, in massive photometric time series databases in general.

show abstract

White dwarf-open cluster associations based on Gaia DR2

Cited by 14 publications

References 72 publications

The origin of early-type runaway stars from open clusters

The origin of early-type runaway stars from open clusters

Massive White Dwarfs in Young Star Clusters

A case study of ACV variables discovered in the Zwicky Transient Facility survey

Contact Info

Product

Resources

About