Magnetic Ap Stars in the Hertzsprung‐Russell Diagram

Hubrig, S.; North, P.; Mathys, G.

doi:10.1086/309189

Cited by 189 publications

(255 citation statements)

References 8 publications

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“…Note that the BC values of Schmidt-Kaler, which are sometimes used for Ap stars (e.g., Hubrig et al 2000) are systematically too negative compared to the more accurate data of Code et al (1976) and Malagnini et al (1986), and differ from the calibration adopted here by about 0.25 mag.…”

Section: Bolometric Correctionsmentioning

confidence: 53%

“…This problem has been previously discussed, among others, by Hubrig et al (2000), Table 1. Slopes of regression lines in Fig.…”

Section: Does Magnetic Fields Strength Change With With Time?mentioning

confidence: 69%

“…We have investigated the reasons for the discrepancies between our conclusions and those of Hubrig et al (2000) and we have identified several points that may have led them to obtain incorrect results. i) Hubrig et al (2000) have used the bolometric corrections of Schmidt-Kaler, which are too large even compared to the most accurate values for normal stars, and lead to an overestimate of bolometric magnitude relative to the BC's adopted here (see Fig.…”

Section: Does Magnetic Fields Strength Change With With Time?mentioning

confidence: 88%

“…i) Hubrig et al (2000) have used the bolometric corrections of Schmidt-Kaler, which are too large even compared to the most accurate values for normal stars, and lead to an overestimate of bolometric magnitude relative to the BC's adopted here (see Fig. 1) by about 0.25 mag (0.1 dex in log(L/L )).…”

Section: Does Magnetic Fields Strength Change With With Time?mentioning

confidence: 96%

“…Based on the analysis of field stars, Hubrig et al (2000) have proposed that, in stars with M < ∼ 3 M , a magnetic field appears at the surface of an Ap stars only after about 30% of its main sequence liftime has elapsed. This conclusion was later reaffirmed by Hubrig et al (2005a,b).…”

Section: Does Magnetic Fields Strength Change With With Time?mentioning

confidence: 99%

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Searching for links between magnetic fields and stellar evolution

Landstreet¹,

Bagnulo²,

Andretta³

et al. 2007

A&A

178

249

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Context. The evolution of magnetic fields in Ap stars during the main sequence phase is presently mostly unconstrained by observation because of the difficulty of assigning accurate ages to known field Ap stars. Aims. We are carrying out a large survey of magnetic fields in cluster Ap stars with the goal of obtaining a sample of these stars with well-determined ages. In this paper we analyse the information available from the survey as it currently stands. Methods. We select from the available observational sample the stars that are probably (1) cluster or association members and (2) magnetic Ap stars. For the stars in this subsample we determine the fundamental parameters T eff , L/L , and M/M . With these data and the cluster ages we assign both absolute age and fractional age (the fraction of the main sequence lifetime completed). For this purpose we have derived new bolometric corrections for Ap stars. Results. Magnetic fields are present at the surfaces of Ap stars from the ZAMS to the TAMS. Statistically for the stars with M > 3 M the fields decline with advancing age approximately as expected from flux conservation together with increased stellar radius, or perhaps even faster than this rate, on a time scale of about 3 × 10 7 yr. In contrast, lower mass stars show no compelling evidence for field decrease even on a timescale of several times 10 8 yr. Conclusions. Study of magnetic cluster stars is now a powerful tool for obtaining constraints on evolution of Ap stars through the main sequence. Enlarging the sample of known cluster magnetic stars, and obtaining more precise rms fields, will help to clarify the results obtained so far. Further field observations are in progress.

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Section: Bolometric Correctionsmentioning

confidence: 53%

“…This problem has been previously discussed, among others, by Hubrig et al (2000), Table 1. Slopes of regression lines in Fig.…”

Section: Does Magnetic Fields Strength Change With With Time?mentioning

confidence: 69%

Section: Does Magnetic Fields Strength Change With With Time?mentioning

confidence: 88%

Section: Does Magnetic Fields Strength Change With With Time?mentioning

confidence: 96%

Section: Does Magnetic Fields Strength Change With With Time?mentioning

confidence: 99%

See 3 more Smart Citations

Searching for links between magnetic fields and stellar evolution

Landstreet¹,

Bagnulo²,

Andretta³

et al. 2007

A&A

178

249

View full text Add to dashboard Cite

show abstract

References

2013

Magnetic Processes in Astrophysics

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Evolution of magnetic fields in stars across the upper main sequence: I. Catalogue of magnetic field measurements with FORS 1 at the VLT

Hubrig¹,

et al. 2006

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To properly understand the physics of Ap and Bp stars it is particularly important to identify the origin of their magnetic fields. For that, an accurate knowledge of the evolutionary state of stars that have a measured magnetic field is an important diagnostic. Previous results based on a small and possibly biased sample suggest that the distribution of magnetic stars with mass below 3 M in the H-R diagram differs from that of normal stars in the same mass range (Hubrig et al. 2000). In contrast, higher mass magnetic Bp stars may well occupy the whole main-sequence width (Hubrig, Schöller & North 2005b). In order to rediscuss the evolutionary state of upper main sequence magnetic stars, we define a larger and bias-free sample of Ap and Bp stars with accurate Hipparcos parallaxes and reliably determined longitudinal magnetic fields. We used FORS 1 at the VLT in its spectropolarimetric mode to measure the magnetic field in chemically peculiar stars where it was unknown or poorly known as yet. In this first paper we present our results of the mean longitudinal magnetic field measurements in 136 stars. Our sample consists of 105 Ap and Bp stars, two PGa stars, 17 HgMn stars, three normal stars, and nine SPB stars. A magnetic field was for the first time detected in 57 Ap and Bp stars, in four HgMn stars, one PGa star, one normal B-type star and four SPB stars.

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Magnetic Ap Stars in the Hertzsprung‐Russell Diagram

Cited by 189 publications

References 8 publications

Searching for links between magnetic fields and stellar evolution

Searching for links between magnetic fields and stellar evolution

References

Evolution of magnetic fields in stars across the upper main sequence: I. Catalogue of magnetic field measurements with FORS 1 at the VLT

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