A Spectroscopic Orbit for the Late-type Be Star β CMi

Richardson, Noel D.; Gerhartz, Cody; Bjorkman, J. E.; Bjorkman, K. S.; Carciofi, A. C.; Klement, Róbert; Wang, Luqian; Morrison, N. D.; Bratcher, A. D.; Greco, Jennifer J.; Hardegree-Ullman, Kevin K.; Lembryk, Ludwik; Trucks, Jesica

doi:10.3847/1538-4357/836/1/112

Cited by 16 publications

(30 citation statements)

References 32 publications

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“…They preferred the shorther period, which they identified with the star binary orbital period. Subsequently, Dulaney et al (2017) analysed RVs from 124 Ritter Observatory echelle spectra, measured on the steep wings of the Hα emission by an automatic procedure and concluded that the star is a single-line binary with a low semiamplitude of (2.25 ± 0.4) km s −1 and an orbital period of 170. d 4±4. d 3.…”

Section: Current Knowledge About β CMImentioning

confidence: 99%

“…Since the orbital RV curve obtained by Dulaney et al (2017) shows a large scatter, and since we have access to several independent sets of electronic spectra of β CMi, we decided to reinvestigate the duplicity of this star, its time variability on several time scales and its physical properties. The results are reported in this study.…”

Section: Current Knowledge About β CMImentioning

confidence: 99%

“…Being aware of this problem, Dulaney et al (2017) applied the IRAF task telluric to get rid of them. Regrettably, they do not provide any details other than that they used spectra of rapidly rotating hot stars obtained with the same spectrograph as their spectra of β CMi.…”

Section: Radial Velocities Of β CMImentioning

confidence: 99%

“…In Fig. 3c we also plot the Hα emission RVs obtained by Dulaney et al (2017), and Fig. 3d we display the strength of the Hα emission.…”

Section: Rvs Of the Hα Emission Wingsmentioning

confidence: 99%

“…To investigate these variations in a more quantitative way, we formally used the program FOTEL for binary orbital solutions and allowed different systemic velocities for the two data sets. RVs de- The periodogram of Dulaney et al (2017) RVs indicate the highest peaks at frequencies of 0.00016869 c d −1 , and 0.0029678 c d −1 . The latter corresponds to a period of 336. d 95, i.e.…”

Section: Photographic Rvsmentioning

confidence: 99%

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A New Look into Putative Duplicity and Pulsations of the Be Star β CMi*

Harmanec

Švanda

Korčáková

et al. 2019

ApJ

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Bright Be star β CMi has been identified as a non-radial pulsator on the basis of space photometry with the MOST satellite and also as a single-line spectroscopic binary with a period of 170. d 4. The purpose of this study is to re-examine both these findings, using numerous electronic spectra from the Dominion Astrophysical Observatory, Ondřejov Observatory, Universitätssterwarte Bochum, archival electronic spectra from several observatories, and also the original MOST satellite photometry. We measured the radial velocity of the outer wings of the double Hα emission in all spectra at our disposal and were not able to confirm significant radial-velocity changes. We also discuss the problems related to the detection of very small radial-velocity changes and conclude that while it is still possible that the star is a spectroscopic binary, there is currently no convincing proof of it from the radial-velocity measurements. Wavelet analysis of the MOST photometry shows that there is only one persistent (and perhaps slightly variable) periodicity of 0. d 617 of the light variations, with a doublewave light curve, all other short periods having only transient character. Our suggestion that this dominant period is the star's rotational period agrees with the estimated stellar radius, projected rotational velocity and with the orbital inclination derived by two teams of investigators. New spectral observations obtained in the whole-night series would be needed to find out whether some possibly real, very small radial-velocity changes cannot in fact be due to rapid line-profile changes.

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Section: Current Knowledge About β CMImentioning

confidence: 99%

Section: Current Knowledge About β CMImentioning

confidence: 99%

Section: Radial Velocities Of β CMImentioning

confidence: 99%

“…In Fig. 3c we also plot the Hα emission RVs obtained by Dulaney et al (2017), and Fig. 3d we display the strength of the Hα emission.…”

Section: Rvs Of the Hα Emission Wingsmentioning

confidence: 99%

Section: Photographic Rvsmentioning

confidence: 99%

See 3 more Smart Citations

A New Look into Putative Duplicity and Pulsations of the Be Star β CMi*

Harmanec

Švanda

Korčáková

et al. 2019

ApJ

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Revealing the structure of the outer disks of Be stars

Klement

Carciofi

Rivinius

et al. 2017

A&A

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Context. The structure of the inner parts of Be star disks ( 20 stellar radii) is well explained by the viscous decretion disk (VDD) model, which is able to reproduce the observable properties of most of the objects studied so far. The outer parts, on the other hand, are not observationally well-explored, as they are observable only at radio wavelengths. A steepening of the spectral slope somewhere between infrared and radio wavelengths was reported for several Be stars that were previously detected in the radio, but a convincing physical explanation for this trend has not yet been provided. Aims. We test the VDD model predictions for the extended parts of a sample of six Be disks that have been observed in the radio to address the question of whether the observed turndown in the spectral energy distribution (SED) can be explained in the framework of the VDD model, including recent theoretical development for truncated Be disks in binary systems. Methods. We combine new multi-wavelength radio observations from the Karl. G. Jansky Very Large Array (JVLA) and Atacama Pathfinder Experiment (APEX) with previously published radio data and archival SED measurements at ultraviolet, visual, and infrared wavelengths. The density structure of the disks, including their outer parts, is constrained by radiative transfer modeling of the observed spectrum using VDD model predictions. In the VDD model we include the presumed effects of possible tidal influence from faint binary companions.Results. For 5 out of 6 studied stars, the observed SED shows strong signs of SED turndown between far-IR and radio wavelengths. A VDD model that extends to large distances closely reproduces the observed SEDs up to far IR wavelengths, but fails to reproduce the radio SED. Using a truncated VDD model improves the fit, leading to a successful explanation of the SED turndown observed for the stars in our sample. The slope of the observed SEDs in the radio is however not well reproduced by disks that are simply cut off at a certain distance. Rather, some matter seems to extend beyond the truncation radius, where it still contributes to the observed SEDs, making the spectral slope in the radio shallower. This finding is in agreement with our current understanding of binary truncation from hydrodynamical simulations, in which the disk does extend past the truncation radius. Therefore, the most probable cause for the SED turndown is the presence of binary companions that remain undetected for most of our sources.

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The historical active episodes of the disks around γ Cassiopeiae (B0.5 IVe) and 59 Cygni (B1 IVe) revisited

Baade,

Labadie-Bartz,

Rivinius

et al. 2023

A&A

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The observations of all known major activity phases of the disks around the classical Be stars γ Cas and 59 Cyg with low-mass companions are comprehensively reviewed and purely qualitatively evaluated again, though taking advantage of new insights gained over the past 25 yr into the physics of Be disks. Both stars have exhibited activity cycles in the violet-to-red (V/R) flux ratio of emission lines with two peaks. This activity is indistinguishable from those of the vast majority of Be stars and so probably were caused by one-armed (m = 1) disk oscillations. The anomalous high-activity phases from 1932 to 1942 in γ Cas and between 1972 and 1976 in 59 Cyg were distinguished from m = 1 density waves by large variations in the separations of pairs of emission peaks. In two consecutive cycles, shell phases during which the emission peaks were maximally separated alternated with single (blended) emission peaks. The amplitude in peak separation of more than a factor of two implies a high-amplitude variation in the disk aspect angle. When the peaks were blended and the disk was viewed closest to face-on, local maxima in visual brightness probably occurred in γ Cas, and the visibility of the stellar absorption lines was reduced, as is expected from increased free-bound emission into the line of sight (there is no time-resolved photometry for 59 Cyg from the event in the 1970s). In y Cas, the pre-event V/R variability (pre-event observations of 59 Cyg do not exist) was practically identical to m = 1 variability. In spite of the subsequent rapid rise in amplitude (up to ~4), the V/R variations connected smoothly in phase but may require an explanation involving the 3D structure of the disk. The phasing of single-peak and shell stages relative to the V/R activity was the same in both cycles of γ Cas, whereas this is not clear for 59 Cyg. During both high-activity cycles of γ Cas, but at different phases, transient additional pairs of emission lines appeared in γ Cas that were much sharper than the main ones and they also had different peak separations and V/R ratios. In the second instance, their velocities were up to ~+500 km s−1. The extremely rapid excitation of the activity phases and their short duration of only two cycles in both stars may indicate a resonant behavior of an unidentified nature. In both stars, the line emission was strongly developed at the onset of the high-activity phases but it basically disappeared at the end of them, and the disks may have been dynamically destroyed. The atypical disk variations were presumably triggered by enhanced interactions between a disk and companion star. In both systems, there seems to be less evidence for a mass-loss outburst than for a reduced mass-injection rate into the disk. The resulting lower viscous coupling between a disk and star would have facilitated the tilting of the disk.

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A Spectroscopic Orbit for the Late-type Be Star β CMi

Cited by 16 publications

References 32 publications

A New Look into Putative Duplicity and Pulsations of the Be Star β CMi*

A New Look into Putative Duplicity and Pulsations of the Be Star β CMi*

Revealing the structure of the outer disks of Be stars

The historical active episodes of the disks around γ Cassiopeiae (B0.5 IVe) and 59 Cygni (B1 IVe) revisited

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