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Jorge Melendez - One of the best experts on this subject based on the ideXlab platform.
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an absolutely calibrated effective Temperature Scale from the infrared flux method
2010Co-Authors: L Casagrande, Jorge Melendez, I Ramirez, M S Bessell, Martin AsplundAbstract:Various effective Temperature Scales have been proposed over the years. Despite much work and the high internal precision usually achieved, systematic differences of order 100 K (or more) among various Scales are still present. We present an investigation based on the Infrared Flux Method aimed at assessing the source of such discrepancies and pin down their origin. We break the impasse among different Scales by using a large set of solar twins, stars which are spectroscopically and photometrically identical to the Sun, to set the absolute zero point of the effective Temperature Scale to within few degrees. Our newly calibrated, accurate and precise Temperature Scale applies to dwarfs and subgiants, from super-solar metallicities to the most metal-poor stars currently known. At solar metallicities our results validate spectroscopic effective Temperature Scales, whereas for [Fe/H]<-2.5 our Temperatures are roughly 100 K hotter than those determined from model fits to the Balmer lines and 200 K hotter than those obtained from the excitation equilibrium of Fe lines. Empirical bolometric corrections and useful relations linking photometric indices to effective Temperatures and angular diameters have been derived. Our results take full advantage of the high accuracy reached in absolute calibration in recent years and are further validated by interferometric angular diameters and space based spectrophotometry over a wide range of effective Temperatures and metallicities.
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The Effective Temperature Scale of FGK Stars. II. Teff:Color:[Fe/H] Calibrations
2005Co-Authors: Ivan Ramirez, Jorge MelendezAbstract:We present up-to-date metallicity-dependent Temperature versus color calibrations for main-sequence and giant stars based on Temperatures derived with the infrared flux method (IRFM). Seventeen colors in the photometric systems UBV, uvby, Vilnius, Geneva, RI(Cousins), DDO, Hipparcos-Tycho, and Two Micron All Sky Survey (2MASS) have been calibrated. The spectral types covered by the calibrations range from F0 to K5 (7000 K Teff 4000 K) with some relations extending below 4000 K or up to 8000 K. Most of the calibrations are valid in the metallicity range -3.5 [Fe/H] 0.4, although some of them extend to as low as [Fe/H] ~ -4.0. All fits to the data have been performed with more than 100 stars; standard deviations range from 30 to 120 K. Fits were carefully performed and corrected to eliminate the small systematic errors introduced by the calibration formulae. Tables of colors as a function of Teff and [Fe/H] are provided. This work is largely based on the study by A. Alonso and collaborators; thus, our relations do not significantly differ from theirs except for the very metal-poor hot stars. From the calibrations, the Temperatures of 44 dwarf and giant stars with direct Temperatures available are obtained. The comparison with direct Temperatures confirms our finding in Paper I that the zero point of the IRFM Temperature Scale is in agreement, to the 10 K level, with the absolute Temperature Scale (that based on stellar angular diameters) within the ranges of atmospheric parameters covered by those 44 stars. The colors of the Sun are derived from the present IRFM Teff Scale and they compare well with those of five solar analogs. It is shown that if the IRFM Teff Scale accurately reproduces the Temperatures of very metal-poor stars, systematic errors of the order of 200 K, introduced by the assumption of (V - K) being completely metallicity independent when studying very metal-poor dwarf stars, are no longer acceptable. Comparisons with other Teff Scales, both empirical and theoretical, are also shown to be in reasonable agreement with our results, although it seems that both Kurucz and MARCS synthetic colors fail to predict the detailed metallicity dependence, given that for [Fe/H] = -2.0, differences as high as approximately ±200 K are found.
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the effective Temperature Scale of fgk stars i determination of Temperatures and angular diameters with the infrared flux method
2005Co-Authors: Ivan Ramirez, Jorge MelendezAbstract:The infrared flux method (IRFM) has been applied to a sample of 135 dwarf and 36 giant stars covering the following regions of the atmospheric parameter space: (1) the metal-rich ([Fe/H] 0) end (consisting mostly of planet-hosting stars), (2) the cool (Teff 5000 K) metal-poor (-1 [Fe/H] -3) dwarf region, and (3) the very metal-poor ([Fe/H] -2.5) end. These stars were especially selected to cover gaps in previous works on Teff versus color relations, particularly the IRFM Teff Scale of A. Alonso and collaborators. Our IRFM implementation was largely based on the Alonso et al. study (absolute infrared flux calibration, bolometric flux calibration, etc.) with the aim of extending the ranges of applicability of their Teff versus color calibrations. In addition, in order to improve the internal accuracy of the IRFM Teff Scale, we recomputed the Temperatures of almost all stars from the Alonso et al. work using updated input data. The updated Temperatures do not significantly differ from the original ones, with few exceptions, leaving the Teff Scale of Alonso et al. mostly unchanged. Including the stars with updated Temperatures, a large sample of 580 dwarf and 470 giant stars (in the field and in clusters), which cover the ranges 3600 K Teff 8000 K and -4.0 [Fe/H] +0.5, have Teff homogeneously determined with the IRFM. The mean uncertainty of the Temperatures derived is 75 K for dwarfs and 60 K for giants, which is about 1.3% at solar Temperature and 4500 K, respectively. It is shown that the IRFM Temperatures are reliable in an absolute Scale given the consistency of the angular diameters resulting from the IRFM with those measured by long baseline interferometry, lunar occultation, and transit observations. Using the measured angular diameters and bolometric fluxes, a comparison is made between IRFM and direct Temperatures, which shows excellent agreement, with the mean difference being less than 10 K for giants and about 20 K for dwarf stars (the IRFM Temperatures being larger in both cases). This result was obtained for giants in the ranges 3800 K < Teff < 5000 K and -0.7 < [Fe/H] < 0.2 and dwarfs in the ranges 4000 K < Teff < 6500 K and -0.55 < [Fe/H] < 0.25; thus, the zero point of the IRFM Teff Scale is essentially the absolute one (that derived from angular diameters and bolometric fluxes) within these limits. The influence of the bolometric flux calibration adopted is explored and it is shown that its effect on the Teff Scale, although systematic, is conservatively no larger than 50 K. Finally, a comparison with Temperatures derived with other techniques is made. Agreement is found with the Temperatures from Balmer line profile fitting and the surface brightness technique. The Temperatures derived from the spectroscopic equilibrium of Fe I lines are differentially consistent with the IRFM, but a systematic difference of about 100 and 65 K (the IRFM Temperatures being lower) is observed in the metal-rich dwarf and metal-poor giant Teff Scales, respectively.
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the effective Temperature Scale of fgk stars ii teff color fe h calibrations
2005Co-Authors: Ivan Ramirez, Jorge MelendezAbstract:We present up-to-date metallicity-dependent Temperature vs. color calibrations for main sequence and giant stars based on Temperatures derived with the infrared flux method (IRFM). Seventeen colors in the following photometric systems: UBV, uvby, Vilnius, Geneva, RI(Cousins), DDO, Hipparcos-Tycho, and 2MASS, have been calibrated. The spectral types covered range from F0 to K5 (7000 K
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the effective Temperature Scale of fgk stars i determination of Temperatures and angular diameters with the infrared flux method
2005Co-Authors: Ivan Ramirez, Jorge MelendezAbstract:The infrared flux method (IRFM) has been applied to a sample of 135 dwarf and 36 giant stars covering the following regions of the atmospheric parameters space: 1) the metal-rich ([Fe/H]>0) end (consisting mostly of planet-hosting stars), 2) the cool (Teff<5000 K) metal-poor (-1<[Fe/H]<-3) dwarf region, and 3) the very metal-poor ([Fe/H]<-2.5) end. These stars were especially selected to cover gaps in previous works on Teff vs. color relations, particularly the IRFM Teff Scale of A. Alonso and collaborators. Our IRFM implementation was largely based on the Alonso et al. study (absolute infrared flux calibration, bolometric flux calibration, etc.) with the aim of extending the ranges of applicability of their Teff vs. color calibrations. In addition, in order to improve the internal accuracy of the IRFM Teff Scale, we recomputed the Temperatures of almost all stars from the Alonso et al. work using updated input data. The updated Temperatures do not significantly differ from the original ones, with few exceptions, leaving the Teff Scale of Alonso et al. mostly unchanged. Including the stars with updated Temperatures, a large sample of 580 dwarf and 470 giant stars (in the field and in clusters), which cover the ranges: 3600 K
Philip Massey - One of the best experts on this subject based on the ideXlab platform.
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The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought
2005Co-Authors: Emily M Levesque, Philip Massey, B Plez, E Josselin, Andre Maeder, K. A. G. Olsen, Georges MeynetAbstract:We use moderate-resolution optical spectrophotometry and the new MARCS stellar atmosphere models to determine the effective Temperatures of 74 Galactic red supergiants (RSGs). The stars are mostly members of OB associations or clusters with known distances, allowing a critical comparison with modern stellar evolutionary tracks. We find we can achieve excellent matches between the observations and the reddened model fluxes and molecular transitions, although the atomic lines Ca I ?4226 and Ca II H and K are found to be unrealistically strong in the models. Our new effective Temperature Scale is significantly warmer than those in the literature, with the differences amounting to 400 K for the latest type M supergiants (i.e., M5 I). We show that the newly derived Temperatures and bolometric corrections give much better agreement with stellar evolutionary tracks. This agreement provides a completely independent verification of our new Temperature Scale. The combination of effective Temperature and bolometric luminosities allows us to calculate stellar radii; the coolest and most luminous stars (KW Sgr, Case 75, KY Cyg, HD 206936=? Cep) have radii of roughly 1500 Rsolar (7 AU), in excellent accordance with the largest stellar radii predicted from current evolutionary theory, although smaller than that found by others for the binary VV Cep and for the peculiar star VY CMa. We find that similar results are obtained for the effective Temperatures and bolometric luminosities using only the dereddened V-K colors, providing a powerful demonstration of the self-consistency of the MARCS models.
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the physical properties and effective Temperature Scale of o type stars as a function of metallicity ii analysis of 20 more magellanic cloud stars and results from the complete sample
2005Co-Authors: Philip Massey, J Puls, A W A Pauldrach, Fabio Bresolin, Rolf P Kudritzki, T SimonAbstract:In order to determine the physical properties of the hottest and most luminous stars and understand how these properties change as a function of metallicity, we have analyzed HST/UV and high-S/N optical spectra of an additional 20 Magellanic Cloud stars, doubling the sample presented in the first paper in this series. Our analysis uses non-LTE line-blanketed models that include spherical extension and the hydrodynamics of the stellar wind. In addition, our data set includes FUSE observations of O VI and HST near-UV He I and He II lines to test for consistency of our derived stellar properties for a few stars. The results from the complete sample are as follows: (1) We present an effective Temperature Scale for O stars as a function of metallicity. We find that the SMC O3-7 dwarfs are 4000 K hotter than Galactic stars of the same spectral type. The difference is in the sense expected due to the decreased significance of line blanketing and wind blanketing at the lower metallicities that characterize the SMC. The Temperature difference between the SMC and Milky Way O dwarfs decreases with decreasing Temperature, becoming negligible by spectral type B0, in accord with the decreased effects of stellar winds at lower Temperatures and luminosities. The Temperatures of the LMC stars appear to be intermediate between that of the Milky Way and SMC, as expected based on their metallicities. Supergiants show a similar effect but are roughly 3000-4000 K cooler than dwarfs for early O stars, also with a negligible difference by B0. The giants appear to have the same effective Temperature Scale as dwarfs, consistent with there being little difference in the surface gravities. When we compare our Scale to other recent modeling efforts, we find good agreement with some CMFGEN results, while other CMFGEN studies are discordant, although there are few individual stars in common. WM-BASIC modeling by others has resulted in significantly cooler effective Temperatures than what we find, as does the recent TLUSTY/CMFGEN study of stars in the NGC 346 cluster, but our results lead to a far more coeval placement of stars in the H-R diagram for this cluster. (2) We find that the wind momentum of these stars Scales with luminosity and metallicity in the ways predicted by radiatively driven wind theory, supporting the use of photospheric analyses of hot luminous stars as a distance indicator for galaxies with resolved massive star populations. (3) A comparison of the spectroscopic masses with those derived from stellar evolutionary theory shows relatively good agreement for stars with effective Temperatures below 45,000 K; however, stars with higher Temperatures all show a significant mass discrepancy, with the spectroscopic masses a factor of 2 or more smaller than the evolutionary masses. This problem may in part be due to unrecognized binaries in our sample, but the result suggests a possible systematic problem with the surface gravities or stellar radii derived from our models. (4) Our sample contains a large number of stars of the earliest O types, including those of the newly proposed O2 subtype. We provide the first quantitative descriptions of their defining spectral characteristics and investigate whether the new types are a legitimate extension of the effective Temperature sequence. We find that the N III/N IV emission line ratio used to define the new classes does not, by itself, serve as an effective Temperature indicator within a given luminosity class: there are O3.5 V stars that are as hot or hotter than O2 V stars. However, the He I/He II ratio does not fair much better for stars this hot, as we find that He I λ4471/He II λ4542, usually taken primarily as a Temperature indicator, becomes sensitive to both the mass-loss rate and surface gravities for the hottest stars. This emphasizes the need to rely on all of the spectroscopic diagnostic lines, and not simply N III/N IV or even He I/He II, for these extreme objects. (5) The two stars with the most discordant radial velocities in our sample happen to be O3 field stars, i.e., found far from the nearest OB associations. This provides the first compelling observational evidence as to the origin of the field O stars in the Magellanic Clouds, i.e., that these are classic runaway OB stars, ejected from their birthplaces.
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the effective Temperature Scale of galactic red supergiants cool but not as cool as we thought
2005Co-Authors: Emily M Levesque, Philip Massey, K Olsen, B Plez, E Josselin, Andre Maeder, Georges MeynetAbstract:We use moderate-resolution optical spectrophotometry and the new MARCS stellar atmosphere models to determine the effective Temperatures of 74 Galactic red supergiants. From these we find a new effective Temperature Scale that is significantly warmer than those in the literature. We show that this Temperature Scale, along with the newly derived bolometric corrections, gives much better agreement between our red supergiants and stellar evolutionary tracks. This agreement provides an independent verification of our new Temperature Scale. The combination of effective Temperature and bolometric luminosities allows us to calculate stellar radii; the coolest and most luminous stars have radii of roughly 1500 solar radii (7 AU), in excellent accordance with the largest stellar radii predicted from current evolutionary theory. We find that similar results are obtained for the effective Temperatures and bolometric luminosities using only the de-reddened V-K colors, providing a powerful demonstration of the self-consistency of the MARCS models.
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the physical properties and effective Temperature Scale of o type stars as a function of metallicity i a sample of 20 stars in the magellanic clouds
2004Co-Authors: Philip Massey, J Puls, Fabio Bresolin, Rolf P Kudritzki, A W A PauldrachAbstract:We have obtained Hubble Space Telescope (HST) and ground-based observations of a sample of 20 O-type stars in the LMC and SMC, including six of the hottest massive stars known (subtypes O2-O3) in the R136 cluster. In general, these data include (1) the HST UV spectra in order to measure the terminal velocities of the stellar winds, (2) high signal-to-noise, blue-optical data where the primary Temperature- and gravity-sensitive photospheric lines are found, and (3) nebular-free H? profiles, which provide the mass-loss rates. We find that the older (Faint Object Spectrograph) HST data of the R136 stars (which were obtained without the benefits of sky measurements) suffered from significant nebular emission, which would increase the derived mass-loss rates by factors of ~3, all other factors being equal. We also find several stars in the SMC for which the N III ??4634, 4642 and He II ?4686 emission f characteristics do not appear to follow the same pattern as in Galactic stars. Since He II emission is due to the stellar wind (which will be weaker in SMC for stars of the same luminosity), while N III emission is a complex non-LTE (NLTE) effect affected mostly by Temperature, it would not be surprising to find that these features do not correlate with each other or with luminosity in SMC stars in the same was as they do in Galactic stars, but theory does not provide a clean answer, and analysis of more stars (both SMC and Galactic) is needed to resolve this issue. The line-blanketed NLTE atmosphere code FASTWIND was then used to determine the physical parameters of this sample of stars. We find good agreement between the synthetic line profiles for the hydrogen, He I, and He II lines in the majority of the stars we analyzed; the three exceptions show evidence of being incipiently resolved spectroscopic binaries or otherwise spectral composites. One such system is apparently an O3 V+O3 V eclipsing binary, and a follow-up radial velocity study is planned to obtain Keplerian masses. Although we did not use them to constrain the fits, good agreement is also found for the He I ?3187 and He II ?3203 lines in the near-UV, which we plan to exploit in future studies. Our effective Temperatures are compared with those recently obtained by Repolust, Puls & Herrero for a sample of Galactic stars using the same techniques. We find that the Magellanic Cloud sample is 3000-4000 K hotter than their Galactic counterparts for the early through mid-O typess. These higher Temperatures are the consequence of a decreased importance of wind emission, wind blanketing, and metal-line blanketing at lower metallicities.
Ivan Ramirez - One of the best experts on this subject based on the ideXlab platform.
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The Effective Temperature Scale of FGK Stars. II. Teff:Color:[Fe/H] Calibrations
2005Co-Authors: Ivan Ramirez, Jorge MelendezAbstract:We present up-to-date metallicity-dependent Temperature versus color calibrations for main-sequence and giant stars based on Temperatures derived with the infrared flux method (IRFM). Seventeen colors in the photometric systems UBV, uvby, Vilnius, Geneva, RI(Cousins), DDO, Hipparcos-Tycho, and Two Micron All Sky Survey (2MASS) have been calibrated. The spectral types covered by the calibrations range from F0 to K5 (7000 K Teff 4000 K) with some relations extending below 4000 K or up to 8000 K. Most of the calibrations are valid in the metallicity range -3.5 [Fe/H] 0.4, although some of them extend to as low as [Fe/H] ~ -4.0. All fits to the data have been performed with more than 100 stars; standard deviations range from 30 to 120 K. Fits were carefully performed and corrected to eliminate the small systematic errors introduced by the calibration formulae. Tables of colors as a function of Teff and [Fe/H] are provided. This work is largely based on the study by A. Alonso and collaborators; thus, our relations do not significantly differ from theirs except for the very metal-poor hot stars. From the calibrations, the Temperatures of 44 dwarf and giant stars with direct Temperatures available are obtained. The comparison with direct Temperatures confirms our finding in Paper I that the zero point of the IRFM Temperature Scale is in agreement, to the 10 K level, with the absolute Temperature Scale (that based on stellar angular diameters) within the ranges of atmospheric parameters covered by those 44 stars. The colors of the Sun are derived from the present IRFM Teff Scale and they compare well with those of five solar analogs. It is shown that if the IRFM Teff Scale accurately reproduces the Temperatures of very metal-poor stars, systematic errors of the order of 200 K, introduced by the assumption of (V - K) being completely metallicity independent when studying very metal-poor dwarf stars, are no longer acceptable. Comparisons with other Teff Scales, both empirical and theoretical, are also shown to be in reasonable agreement with our results, although it seems that both Kurucz and MARCS synthetic colors fail to predict the detailed metallicity dependence, given that for [Fe/H] = -2.0, differences as high as approximately ±200 K are found.
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the effective Temperature Scale of fgk stars i determination of Temperatures and angular diameters with the infrared flux method
2005Co-Authors: Ivan Ramirez, Jorge MelendezAbstract:The infrared flux method (IRFM) has been applied to a sample of 135 dwarf and 36 giant stars covering the following regions of the atmospheric parameter space: (1) the metal-rich ([Fe/H] 0) end (consisting mostly of planet-hosting stars), (2) the cool (Teff 5000 K) metal-poor (-1 [Fe/H] -3) dwarf region, and (3) the very metal-poor ([Fe/H] -2.5) end. These stars were especially selected to cover gaps in previous works on Teff versus color relations, particularly the IRFM Teff Scale of A. Alonso and collaborators. Our IRFM implementation was largely based on the Alonso et al. study (absolute infrared flux calibration, bolometric flux calibration, etc.) with the aim of extending the ranges of applicability of their Teff versus color calibrations. In addition, in order to improve the internal accuracy of the IRFM Teff Scale, we recomputed the Temperatures of almost all stars from the Alonso et al. work using updated input data. The updated Temperatures do not significantly differ from the original ones, with few exceptions, leaving the Teff Scale of Alonso et al. mostly unchanged. Including the stars with updated Temperatures, a large sample of 580 dwarf and 470 giant stars (in the field and in clusters), which cover the ranges 3600 K Teff 8000 K and -4.0 [Fe/H] +0.5, have Teff homogeneously determined with the IRFM. The mean uncertainty of the Temperatures derived is 75 K for dwarfs and 60 K for giants, which is about 1.3% at solar Temperature and 4500 K, respectively. It is shown that the IRFM Temperatures are reliable in an absolute Scale given the consistency of the angular diameters resulting from the IRFM with those measured by long baseline interferometry, lunar occultation, and transit observations. Using the measured angular diameters and bolometric fluxes, a comparison is made between IRFM and direct Temperatures, which shows excellent agreement, with the mean difference being less than 10 K for giants and about 20 K for dwarf stars (the IRFM Temperatures being larger in both cases). This result was obtained for giants in the ranges 3800 K < Teff < 5000 K and -0.7 < [Fe/H] < 0.2 and dwarfs in the ranges 4000 K < Teff < 6500 K and -0.55 < [Fe/H] < 0.25; thus, the zero point of the IRFM Teff Scale is essentially the absolute one (that derived from angular diameters and bolometric fluxes) within these limits. The influence of the bolometric flux calibration adopted is explored and it is shown that its effect on the Teff Scale, although systematic, is conservatively no larger than 50 K. Finally, a comparison with Temperatures derived with other techniques is made. Agreement is found with the Temperatures from Balmer line profile fitting and the surface brightness technique. The Temperatures derived from the spectroscopic equilibrium of Fe I lines are differentially consistent with the IRFM, but a systematic difference of about 100 and 65 K (the IRFM Temperatures being lower) is observed in the metal-rich dwarf and metal-poor giant Teff Scales, respectively.
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the effective Temperature Scale of fgk stars ii teff color fe h calibrations
2005Co-Authors: Ivan Ramirez, Jorge MelendezAbstract:We present up-to-date metallicity-dependent Temperature vs. color calibrations for main sequence and giant stars based on Temperatures derived with the infrared flux method (IRFM). Seventeen colors in the following photometric systems: UBV, uvby, Vilnius, Geneva, RI(Cousins), DDO, Hipparcos-Tycho, and 2MASS, have been calibrated. The spectral types covered range from F0 to K5 (7000 K
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the effective Temperature Scale of fgk stars i determination of Temperatures and angular diameters with the infrared flux method
2005Co-Authors: Ivan Ramirez, Jorge MelendezAbstract:The infrared flux method (IRFM) has been applied to a sample of 135 dwarf and 36 giant stars covering the following regions of the atmospheric parameters space: 1) the metal-rich ([Fe/H]>0) end (consisting mostly of planet-hosting stars), 2) the cool (Teff<5000 K) metal-poor (-1<[Fe/H]<-3) dwarf region, and 3) the very metal-poor ([Fe/H]<-2.5) end. These stars were especially selected to cover gaps in previous works on Teff vs. color relations, particularly the IRFM Teff Scale of A. Alonso and collaborators. Our IRFM implementation was largely based on the Alonso et al. study (absolute infrared flux calibration, bolometric flux calibration, etc.) with the aim of extending the ranges of applicability of their Teff vs. color calibrations. In addition, in order to improve the internal accuracy of the IRFM Teff Scale, we recomputed the Temperatures of almost all stars from the Alonso et al. work using updated input data. The updated Temperatures do not significantly differ from the original ones, with few exceptions, leaving the Teff Scale of Alonso et al. mostly unchanged. Including the stars with updated Temperatures, a large sample of 580 dwarf and 470 giant stars (in the field and in clusters), which cover the ranges: 3600 K
Bonghak Kim - One of the best experts on this subject based on the ideXlab platform.
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spectral responsivity calibration of the reference radiation thermometer at kriss by using a super continuum laser based high accuracy monochromatic source
2016Co-Authors: Y. S. Yoo, Seongchong Park, D. H. Lee, Gun Jung Kim, Bonghak KimAbstract:We report on the calibration of the relative spectral responsivity of the reference radiation thermometer, model LP4, which is used for the experimental realisation of the international Temperature Scale of 1990 above 960 °C at the Korea Research Institute of Standards and Science. The relative spectral responsivity of LP4 is measured by using a monochromatic source consisting of a super-continuum laser and a double-grating monochromator. By monitoring the wavelength of the output beam directly with a calibrated wavelength-meter, we achieved a high-accuracy measurement of spectral responsivity with a maximum wavelength error of less than 3 pm, a narrow spectral bandwidth of less than 0.4 nm, and a high dynamic range over 8 decades. We evaluated the contributions of various uncertainty components of the spectral responsivity measurement to the uncertainty of the Temperature Scale based on a practical estimation approach, which numerically calculates the maximal effects of the variations of each component. As a result, we evaluate the uncertainty contribution from the spectral responsivity measurement to the Temperature Scale to be less than 64 mK (k = 1) in a range from 660 °C to 2749 °C for the LP4 with a filter at 650 nm.
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realization of a radiation Temperature Scale from 0 c to 232 c by a thermal infrared thermometer based on a multiple fixed point technique
2013Co-Authors: Yong Shim Yoo, Bonghak Kim, Sun Do Lim, Seungnam Park, Seongchong ParkAbstract:The radiation Temperature Scale for a pyroelectric detector based thermal infrared thermometer with its spectral response from 8??m to 14??m was realized in the Temperature range from 0??C to 232??C by using four fixed-point blackbodies (ice, Ga, In and Sn). The Planck version of the Sakuma?Hattori equation was used to interpolate the Scale between the fixed-point Temperatures that are corrected by considering a size-of-source effect (SSE). The expanded uncertainties (k?=?2) of the Scale were estimated to be 108?mK for ice, 99?mK for Ga, 175?mK for In and 234?mK for Sn.
Seongchong Park - One of the best experts on this subject based on the ideXlab platform.
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spectral responsivity calibration of the reference radiation thermometer at kriss by using a super continuum laser based high accuracy monochromatic source
2016Co-Authors: Y. S. Yoo, Seongchong Park, D. H. Lee, Gun Jung Kim, Bonghak KimAbstract:We report on the calibration of the relative spectral responsivity of the reference radiation thermometer, model LP4, which is used for the experimental realisation of the international Temperature Scale of 1990 above 960 °C at the Korea Research Institute of Standards and Science. The relative spectral responsivity of LP4 is measured by using a monochromatic source consisting of a super-continuum laser and a double-grating monochromator. By monitoring the wavelength of the output beam directly with a calibrated wavelength-meter, we achieved a high-accuracy measurement of spectral responsivity with a maximum wavelength error of less than 3 pm, a narrow spectral bandwidth of less than 0.4 nm, and a high dynamic range over 8 decades. We evaluated the contributions of various uncertainty components of the spectral responsivity measurement to the uncertainty of the Temperature Scale based on a practical estimation approach, which numerically calculates the maximal effects of the variations of each component. As a result, we evaluate the uncertainty contribution from the spectral responsivity measurement to the Temperature Scale to be less than 64 mK (k = 1) in a range from 660 °C to 2749 °C for the LP4 with a filter at 650 nm.
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realization of a radiation Temperature Scale from 0 c to 232 c by a thermal infrared thermometer based on a multiple fixed point technique
2013Co-Authors: Yong Shim Yoo, Bonghak Kim, Sun Do Lim, Seungnam Park, Seongchong ParkAbstract:The radiation Temperature Scale for a pyroelectric detector based thermal infrared thermometer with its spectral response from 8??m to 14??m was realized in the Temperature range from 0??C to 232??C by using four fixed-point blackbodies (ice, Ga, In and Sn). The Planck version of the Sakuma?Hattori equation was used to interpolate the Scale between the fixed-point Temperatures that are corrected by considering a size-of-source effect (SSE). The expanded uncertainties (k?=?2) of the Scale were estimated to be 108?mK for ice, 99?mK for Ga, 175?mK for In and 234?mK for Sn.
