Gaia's view of the λ Boo star puzzle

Murphy, Simon J.; Paunzen, E.

doi:10.1093/mnras/stw3141

Cited by 40 publications

(37 citation statements)

References 82 publications

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“…Adopting values that reproduce the observations for T Tauri stars may not be appropriate for these higher mass analogs. Second, early-type stars with metal-poor photospheres, in particular the λBoo stars, show an ultraviolet excess (Murphy & Paunzen 2017). Folsom et al (2012) and Kama et al (2015) found a relatively high fraction of HAeBes in their samples (up to ∼50%) showing the λBoo pattern to varying degrees.…”

Section: Appendix a Scattered-light Disk Samplementioning

confidence: 95%

“…This is a face-on star rotating near its break-up velocity (Grady et al 2007), resulting in a significant deformation of the star and a temperature gradient from the stellar pole to the equatorial region of the star. As part of their study of λBoo stars, Murphy & Paunzen (2017) find T=6700±322K and log L å /L ☉ =0.78±0.03. We adopt these values to estimate the stellar mass and radius from the Siess et al (2000) evolutionary tracks.…”

Section: Appendix D Comment On Individual Systemsmentioning

confidence: 97%

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Spiral Arms in Disks: Planets or Gravitational Instability?

Dong

Najita

Brittain

2018

ApJ

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Spiral arm structures seen in scattered-light observations of protoplanetary disks can potentially serve as signposts of planetary companions. They can also lend unique insights into disk masses, which are critical in setting the mass budget for planet formation but are difficult to determine directly. A surprisingly high fraction of disks that have been well studied in scattered light have spiral arms of some kind (8/29), as do a high fraction (6/11) of wellstudied Herbig intermediate-mass stars (i.e., Herbig stars >1.5 M e ). Here we explore the origin of spiral arms in Herbig systems by studying their occurrence rates, disk properties, and stellar accretion rates. We find that two-arm spirals are more common in disks surrounding Herbig intermediate-mass stars than are directly imaged giant planet companions to mature A and B stars. If two-arm spirals are produced by such giant planets, this discrepancy suggests that giant planets are much fainter than predicted by hot-start models. In addition, the high stellar accretion rates of Herbig stars, if sustained over a reasonable fraction of their lifetimes, suggest that disk masses are much larger than inferred from their submillimeter continuum emission. As a result, gravitational instability is a possible explanation for multiarm spirals. Future observations can lend insights into the issues raised here.

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Section: Appendix a Scattered-light Disk Samplementioning

confidence: 95%

Section: Appendix D Comment On Individual Systemsmentioning

confidence: 97%

Spiral Arms in Disks: Planets or Gravitational Instability?

Dong

Najita

Brittain

2018

ApJ

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“…Significant photospheric depletion of refractory elements, called the λ Boö phenomenon, is seen in ∼ 2 % of B to mid-F type stars (Paunzen & Gray 1997;Paunzen et al 2001;Paunzen 2001;Murphy et al 2015). The λ Boö abundance pattern is seen in young, disk-hosting stars with ages ∼ 0.1 to 10 Myr (Section 4.1) and in stars as old as 1 Gyr, on the order of their main-sequence lifetimes (Murphy & Paunzen 2017). Some λ Boö stars possess debris disks (Draper et al 2016), but the fraction of confirmed debris disks was found to be statistically indistinguishable from that in nonλ Boö sources (Gray et al 2017).…”

Section: λ Boötis Starsmentioning

confidence: 99%

Stellar photospheric abundances as a probe of discs and planets

Jermyn

Kama

2018

Monthly Notices of the Royal Astronomical Society

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Protoplanetary disks, debris disks, and disrupted or evaporating planets can all feed accretion onto stars. The photospheric abundances of such stars may then reveal the composition of the accreted material. This is especially likely in B to mid-F type stars, which have radiative envelopes and hence less bulk-photosphere mixing. We present a theoretical framework (CAM) considering diffusion, rotation, and other stellar mixing mechanisms, to describe how the accreted material interacts with the bulk of the star. This allows the abundance pattern of the circumstellar material to be calculated from measured stellar abundances and parameters (v rot , T eff ). We discuss the λ Boö phenomenon and the application of CAM on stars hosting protoplanetary disks

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“…Therefore, Yushchenko et al (2015) include HD 48497 in their list of possible λ Bootis star candidates. These stars constitute a small group of A-to Ftype stars characterized by the depletion of Fe-peak elements of up to 2 dex (Murphy & Paunzen 2017). However, HD 48497 is too hot and does not show the typical elemental abundance pattern of λ Bootis stars.…”

Section: Objectmentioning

confidence: 99%

Pulsational properties of ten new slowly pulsating B stars

Fedurco

Paunzen

Hümmerich

et al. 2020

A&A

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Context. Slowly pulsating B (SPB) stars are upper main-sequence multi-periodic pulsators that show non-radial g-mode oscillations driven by the κ mechanism acting on the iron bump. These multi-periodic pulsators have great asteroseismic potential and can be employed for the calibration of stellar structure and evolution models of massive stars. Aims. We collected a sample of ten hitherto unidentified SPB stars with the aim of describing their pulsational properties and identifying pulsational modes. Methods. Photometric time series data from various surveys were collected and analyzed using diverse frequency search algorithms. We calculated astrophysical parameters and investigated the location of our sample stars in the log T eff versus log L/L diagram. Current pulsational models were calculated and used for the identification of pulsational modes in our sample stars. An extensive grid of stellar models along with their g-mode eigenfrequencies was calculated and subsequently cross-matched with the observed pulsational frequencies. The best-fit models were then used in an attempt to constrain stellar parameters such as mass, age, metallicity, and convective overshoot. Results. We present detected frequencies, corresponding g-mode identifications, and the masses and ages of the stellar models producing the best frequency cross-matches. We partially succeeded in constraining stellar parameters, in particular concerning mass and age. Where applicable, rotation periods have been derived from the spacing of triplet component frequencies. No evolved SPB stars are present in our sample. We identify two candidate high-metallicity objects (HD 86424 and HD 163285), one young SPB star (HD 36999), and two candidate young SPB stars (HD 61712 and HD 61076). Conclusions. We demonstrate the feasibility of using ground-based observations to perform basic asteroseismological analyses of SPB stars. Our results significantly enlarge the sample of known SPB stars with reliable pulsational mode identifications, which provides important input parameters for modeling attempts aiming to investigate the internal processes at work in upper main-sequence stars.

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Gaia's view of the λ Boo star puzzle

Cited by 40 publications

References 82 publications

Spiral Arms in Disks: Planets or Gravitational Instability?

Spiral Arms in Disks: Planets or Gravitational Instability?

Stellar photospheric abundances as a probe of discs and planets

Pulsational properties of ten new slowly pulsating B stars

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