Rotational Velocities and Chromospheric/Coronal Activity of Low‐Mass Stars in the Young Open Clusters IC 2391 and IC 2602

Stauffer, J. R.; Hartmann, L.; Prosser, Charles F.; Randich, S.; Balachandran, Suchitra C.; Patten, B. M.; Simon, Theodore; Giampapa, M. S.

doi:10.1086/303930

Cited by 179 publications

(230 citation statements)

References 47 publications

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“…Another clear signpost of activity in young stellar and substellar objects is variability. This variability has been observed not only in the continuum but also in a variety of lines, and its dependence with the spectral type has also been addressed in the literature (examples can be found in Soderblom et al 1993;Stauffer et al 1997;Barrado y Navascués et al 2001). In Paper I, we reported a high percentage ( 35%) of the members of C69 showing such variability in alkali lines (lithium and sodium).…”

Section: Variability Connected To Activitymentioning

confidence: 61%

Spectroscopy of very low-mass stars and brown dwarfs in the Lambda Orionis star-forming region

Bayo

Barrado

Huélamo

et al. 2012

A&A

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Context. Most observational studies conducted so far point toward brown dwarfs sharing a similar formation mechanism as the one that is accepted for low-mass stars. However, larger databases and more systematic studies are needed before strong conclusions can be reached. Aims. In this second paper of a series devoted to studying the spectroscopic properties of the Lambda Orionis star-forming region members, we study accretion, activity and rotation for a wide set of spectroscopically confirmed members of the central star cluster Collinder 69 to assess analogies and/or differences between the brown-dwarf and stellar populations of this cluster. Moreover, we present comparisons with other star-forming regions of similar and different ages to address environmental effects on our conclusions. Methods. We studied prominent photospheric lines to derive rotational velocities and emission lines to distinguish between accretion processes and chromospheric activity. In addition, we include information about disk presence and X-ray emission. Results. We report very strong differences in the disk fractions of low-mass stars and brown dwarfs (∼58%) when compared to higher mass stars (26 +4 −3 %), with 0.6 M being the critical mass we find for this dichotomy. As a byproduct, we address the implications of the spatial distribution of disk and diskless members in the formation scenario of the cluster itself. We used the Hα emission to distinguish among accreting and non-accreting sources, finding that 38 +8 −7 % of sources harboring disks undergo active accretion and that his percentage stays similar in the substellar regime. For these sources we have estimated accretion rates. Finally, regarding rotational velocities, we find a high dispersion in v sin(i) that is even higher among the diskless population.

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Section: Variability Connected To Activitymentioning

confidence: 61%

Spectroscopy of very low-mass stars and brown dwarfs in the Lambda Orionis star-forming region

Bayo

Barrado

Huélamo

et al. 2012

A&A

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“…This assumption was confirmed later by Basri (1987). There has been a dramatic increase in the amount and quality of rotation data available for low-mass stars in open clusters and the field, from the important early work of Stauffer & Hartmann (1987) to the present (see Stauffer et al 1997;Krishnamurthi et al 1997;Reid & Mahoney 2000 for reviews). However, many theoretical studies of CVs use angular momentum loss rates (e.g., Rappaport, Verbunt, & Joss 1983) that precede these data.…”

Section: Introductionmentioning

confidence: 87%

Cataclysmic Variables: An Empirical Angular Momentum Loss Prescription from Open Cluster Data

Andronov

Pinsonneault

Sills

2003

ApJ

122

165

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We apply the angular momentum loss rates inferred from open cluster stars to the evolution of cataclysmic variables (CVs). We show that the angular momentum prescriptions used in earlier CV studies are inconsistent with the measured rotation data in open clusters. The timescale for angular momentum loss ( _ J J) above the fully convective boundary is $2 orders of magnitude longer than inferred from the older model, and the observed angular momentum loss properties show no evidence for a change in behavior at the fully convective boundary. This provides evidence against the hypothesis that the period gap is caused by an abrupt change in the angular momentum loss law when the secondary becomes fully convective. Furthermore, the empirical angular momentum loss law implies a timescale for CV evolution that is comparable to a Hubble time; for the same reason, it will be more difficult to produce CVs from the products of common envelope evolution, and it implies a lower space density of CVs. The predicted loss rate for short-period CVs is consistent with the observed period minimum (1.3 hr). We infer the time-averaged mass accretion rate and derive the mass-period relation for different evolutionary states of the secondary. The steady-state accretion rates are significantly lower than the claimed observational rates; we discuss some possible explanations. The mass-period relationship is more consistent with evolved secondaries than with unevolved secondaries above the period gap. Implications for the CV period gap are discussed, including the possibility that two populations of secondaries could produce the gap.

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“…Furthermore, the EW of H α is a function of the spectral type of the star at a given age, e.g. Stauffer et al (1997). In Fig.…”

Section: H α Emissionmentioning

confidence: 99%

Search for associations containing young stars (SACY)

Elliott

Bayo

Melo

et al. 2016

A&A

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Context. The young associations offer us one of the best opportunities to study the properties of young stellar and substellar objects and to directly image planets thanks to their proximity (<200 pc) and age (≈5−150 Myr). However, many previous works have been limited to identifying the brighter, more active members (≈1 M ) owing to photometric survey sensitivities limiting the detections of lower mass objects. Aims. We search the field of view of 542 previously identified members of the young associations to identify wide or extremely wide (1000−100 000 au in physical separation) companions. Methods. We combined 2MASS near-infrared photometry (J, H, K) with proper motion values (from UCAC4, PPMXL, NOMAD) to identify companions in the field of view of known members. We collated further photometry and spectroscopy from the literature and conducted our own high-resolution spectroscopic observations for a subsample of candidate members. This complementary information allowed us to assess the efficiency of our method. Results. We identified 84 targets (45: 0.2−1.3 M , 17: 0.08−0.2 M , 22: <0.08 M ) in our analysis, ten of which have been identified from spectroscopic analysis in previous young association works. For 33 of these 84, we were able to further assess their membership using a variety of properties (X-ray emission, UV excess, H α , lithium and K I equivalent widths, radial velocities, and CaH indices). We derive a success rate of 76-88% for this technique based on the consistency of these properties. Conclusions. Once confirmed, the targets identified in this work would significantly improve our knowledge of the lower mass end of the young associations. Additionally, these targets would make an ideal new sample for the identification and study of planets around nearby young stars. Given the predicted substellar mass of the majority of these new candidate members and their proximity, high-contrast imaging techniques would facilitate the search for new low-mass planets.

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Rotational Velocities and Chromospheric/Coronal Activity of Low‐Mass Stars in the Young Open Clusters IC 2391 and IC 2602

Cited by 179 publications

References 47 publications

Spectroscopy of very low-mass stars and brown dwarfs in the Lambda Orionis star-forming region

Spectroscopy of very low-mass stars and brown dwarfs in the Lambda Orionis star-forming region

Cataclysmic Variables: An Empirical Angular Momentum Loss Prescription from Open Cluster Data

Search for associations containing young stars (SACY)

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