The Determination of Stellar Temperatures From Baron B. Harkányi to the Gaia Mission

Kristóf Petrovay

doi:10.1177/0021828620918961

The Determination of Stellar Temperatures From Baron B. Harkányi to the Gaia Mission

Journal for the History of Astronomy ◽

10.1177/0021828620918961 ◽

2020 ◽

Vol 51 (2) ◽

pp. 152-161

Author(s):

Kristóf Petrovay

Keyword(s):

Surface Temperature ◽

The Sun ◽

150Th Anniversary ◽

Stellar Temperature ◽

History Of ◽

Stellar Temperatures

The first determination of the surface temperature of stars other than the Sun is due to the Hungarian astrophysicist Béla Harkányi. Prompted by the recent unprecedented increase in the availability of stellar temperature estimates from Gaia, coinciding with the 150th anniversary of Harkányi’s birth, this article presents the life and work of this neglected, yet remarkable figure in the context of the history of stellar astrophysics.

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Gaia DR1 completeness within 250 pc & star formation history of the Solar neighbourhood

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317006159 ◽

2017 ◽

Vol 12 (S330) ◽

pp. 148-151 ◽

Cited By ~ 1

Author(s):

Edouard J. Bernard

Keyword(s):

Star Formation ◽

Star Formation History ◽

Solar Neighbourhood ◽

The Sun ◽

Thick Disc ◽

Formation History ◽

Magnitude Diagram ◽

History Of

AbstractWe took advantage of the Gaia DR1 to combine TGAS parallaxes with Tycho-2 and APASS photometry to calculate the star formation history (SFH) of the solar neighbourhood within 250 pc using the colour-magnitude diagram fitting technique. We present the determination of the completeness within this volume, and compare the resulting SFH with that calculated from the Hipparcos catalogue within 80 pc of the Sun. We also show how this technique will be applied out to ~5 kpc thanks to the next Gaia data releases, which will allow us to quantify the SFH of the thin disc, thick disc and halo in situ, rather than extrapolating based on the stars from these components that are today in the solar neighbourhood.

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The Zanstra Temperatures Revisited

Symposium - International Astronomical Union ◽

10.1017/s0074180900208644 ◽

2003 ◽

Vol 209 ◽

pp. 246-246

Author(s):

R. Gruenwald ◽

S. M. Viegas

Keyword(s):

Optical Depth ◽

Careful Analysis ◽

Depth Effect ◽

Single Star ◽

Line Intensity Ratio ◽

Stellar Temperature ◽

Stellar Temperatures ◽

Lower Temperature ◽

Lower Limits

The temperature of the central stars in planetary nebulae is generally obtained by the Zanstra method. This method provides two values for the temperature of a single star: one obtained from the H recombination lines, TZ(H), and another from the He recombination lines, TZ(He II). The ratio (ZR) of these two values can be different from unit, leading to the well-known “Zanstra discrepancy”. The discrepancy is higher for lower temperature stars and the method does not reproduce the high values of stellar temperatures suggested by stellar evolutionary models. In this work a careful analysis of the effect of the optical depth on the determination of the Zanstra temperature is made, using photoionization models. The effects due to deviations from a blackbody spectrum, as well as to the He abundance in the nebulae, are also discussed. We show, quantitatively, that the details of the distribution of the H and He II Zanstra temperatures are mainly explained by an optical depth effect; in particular, the fact that the discrepancy is larger for low stellar temperatures. The results also show that for high stellar temperatures both Zanstra temperatures underestimate the stellar temperature, even for high optical depths. The stellar temperature, as well as the optical depth, can be obtained from a plot of ZR vs. TZ(He II). Since for nebulae of very low optical depth and/or high stellar temperature this plot only provides lower limits for T*, we propose the use of the line intensity ratio He II/He I vs. TZ(He II) diagram for obtaining the stellar temperature, as well as the nebular optical depth. The results of this work has been published in ApJ 543, 889 (2000).

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Galactic orbits of stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900105340 ◽

1966 ◽

Vol 25 ◽

pp. 93-97

Author(s):

Richard Woolley

Keyword(s):

Globular Cluster ◽

Potential Field ◽

High Velocity ◽

Velocity Vector ◽

Variable Stars ◽

The Sun ◽

Proper Motions ◽

Rr Lyrae ◽

The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

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State-by-State Use of AMA Guides

Guides Newsletter ◽

10.1001/amaguidesnewsletters.2019.sepoct01 ◽

2019 ◽

Vol 24 (5) ◽

pp. 3-7, 16

Keyword(s):

Expert Testimony ◽

Narrow Range ◽

The United States ◽

Workers Compensation ◽

Federal Employees ◽

Permanent Disability ◽

Sixth Edition ◽

History Of ◽

Canadian Provinces

Abstract This article presents a history of the origins and development of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), from the publication of an article titled “A Guide to the Evaluation of Permanent Impairment of the Extremities and Back” (1958) until a compendium of thirteen guides was published in book form in 1971. The most recent, sixth edition, appeared in 2008. Over time, the AMA Guides has been widely used by US states for workers’ compensation and also by the Federal Employees Compensation Act, the Longshore and Harbor Workers’ Compensation Act, as well as by Canadian provinces and other jurisdictions around the world. In the United States, almost twenty states have developed some form of their own impairment rating system, but some have a narrow range and scope and advise evaluators to consult the AMA Guides for a final determination of permanent disability. An evaluator's impairment evaluation report should clearly document the rater's review of prior medical and treatment records, clinical evaluation, analysis of the findings, and a discussion of how the final impairment rating was calculated. The resulting report is the rating physician's expert testimony to help adjudicate the claim. A table shows the edition of the AMA Guides used in each state and the enabling statute/code, with comments.

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