scholarly journals Absolute-Magnitude Calibration for Red Giants Based on Colour–Magnitude Diagrams of Galactic Clusters: I. Calibration in V and B–V

2012 ◽  
Vol 29 (4) ◽  
pp. 509-522 ◽  
Author(s):  
S. Karaali ◽  
S. Bilir ◽  
E. Yaz Gökçe
Keyword(s):  
Standard Deviation ◽  
Magnitude Estimation ◽  
Absolute Magnitude ◽  
Red Giants ◽  
Degree Polynomial ◽  
Derived Relations ◽  
Galactic Clusters ◽  
The Mean ◽  
The Absolute ◽  
Effect Of Age

AbstractWe present an absolute-magnitude calibration for red giants using the colour–magnitude diagrams of six Galactic clusters with different metallicities: M92, M13, M5, 47 Tuc, M67 and NGC 6791. The combination of the absolute magnitude offset from the fiducial of giant sequence of the cluster M5 with the corresponding metallicity offset provides a calibration estimation for the absolute magnitude of red giants for a given (B – V)0 colour. The calibration is defined in the colour interval 0.75 ≤ (B – V)0 ≤ 1.50 mag and it covers the metal licity interval −2.15 > [Fe/H]≤+0.37 dex. 91% of the absolute magnitude residuals obtained by the application of the procedure to another set of Galactic clusters lie in the interval −0.40 < ΔM≤+0.40 mag. The mean and the standard deviation of the residuals are 0.05 and 0.19 mag, respectively. We fitted the absolute magnitude also to metallicity and age for a limited sub-sample of (B – V)0 colour, just to test the effect of age in absolute-magnitude calibration. Comparison of the mean and the standard deviation of the residuals evaluated by this procedure with the corresponding ones provided by the procedure where the absolute magnitude fitted to a third degree polynomial of metallicity show that the age parameter may be omitted in absolute magnitude estimation of red giants. The derived relations are applicable to stars older than 4 Gyr, the age of the youngest calibrating cluster.

scholarly journals Absolute Magnitude Calibration for Giants Based on the Colour–Magnitude Diagrams of Galactic Clusters. II. Calibration with SDSS

2013 ◽  
Vol 30 ◽  
Author(s):  
S. Karaali ◽  
S. Bilir ◽  
E. Yaz Gökçe
Keyword(s):  
Standard Deviation ◽  
Magnitude Estimation ◽  
Absolute Magnitude ◽  
Red Giants ◽  
Derived Relations ◽  
Galactic Clusters ◽  
The Mean ◽  
The Absolute ◽  
Red Giant ◽  
Absolute Magnitudes

AbstractWe present an absolute magnitude calibration for red giants with the colour–magnitude diagrams of six Galactic clusters with different metallicities, i.e. M92, M13, M3, M71, NGC 6791, and NGC 2158. The combination of the absolute magnitudes of the red giant sequences with the corresponding metallicities provides calibration for absolute magnitude estimation for red giants for a given (g − r)0 colour. The calibration is defined in the colour interval 0.45 ≤ (g − r)0 ≤ 1.30 mag and it covers the metallicity interval −2.15≤[Fe/H]≤ +0.37 dex. The absolute magnitude residuals obtained by the application of the procedure to another set of Galactic clusters lie in the interval −0.28 < ΔM ≤ +0.43 mag. However, the range of 94% of the residuals is shorter, −0.1 < ΔM ≤ +0.4 mag. The mean and the standard deviation of (all) residuals are 0.169 and 0.140 mag, respectively. The derived relations are applicable to stars older than 2 Gyr, the age of the youngest calibrating cluster.

scholarly journals Absolute Magnitude Calibration for Dwarfs Based on the Colour–Magnitude Diagrams of Galactic Clusters

2014 ◽  
Vol 31 ◽  
Author(s):  
S. Karaali ◽  
E. Yaz Gökçe ◽  
S. Bilir ◽  
S. Tunçel Güçtekin
Keyword(s):  
Standard Deviation ◽  
Absolute Magnitude ◽  
Derived Relations ◽  
Two Systems ◽  
Galactic Clusters ◽  
Solar Metallicity ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes

AbstractWe present two absolute magnitude calibrations for dwarfs based on colour–magnitude diagrams of Galactic clusters. The combination of the Mg absolute magnitudes of the dwarf fiducial sequences of the clusters M92, M13, M5, NGC 2420, M67, and NGC 6791 with the corresponding metallicities provides absolute magnitude calibration for a given (g − r)0 colour. The calibration is defined in the colour interval 0.25 ≤ (g − r)0 ≤ 1.25 mag and it covers the metallicity interval − 2.15 ≤ [Fe/H] ≤ +0.37 dex. The absolute magnitude residuals obtained by the application of the procedure to another set of Galactic clusters lie in the interval − 0.15 ≤ ΔMg ≤ +0.12 mag. The mean and standard deviation of the residuals are < ΔMg > = − 0.002 and σ = 0.065 mag, respectively. The calibration of the MJ absolute magnitude in terms of metallicity is carried out by using the fiducial sequences of the clusters M92, M13, 47 Tuc, NGC 2158, and NGC 6791. It is defined in the colour interval 0.90 ≤ (V − J)0 ≤ 1.75 mag and it covers the same metallicity interval of the Mg calibration. The absolute magnitude residuals obtained by the application of the procedure to the cluster M5 ([Fe/H] = −1.40 dex) and 46 solar metallicity, − 0.45 ≤ [Fe/H] ≤ +0.35 dex, field stars lie in the interval − 0.29 and + 0.35 mag. However, the range of 87% of them is rather shorter, − 0.20 ≤ ΔMJ ≤ +0.20 mag. The mean and standard deviation of all residuals are < ΔMJ > =0.05 and σ = 0.13 mag, respectively. The derived relations are applicable to stars older than 4 Gyr for the Mg calibration, and older than 2 Gyr for the MJ calibration. The cited limits are the ages of the youngest calibration clusters in the two systems.

scholarly journals Absolute Magnitude Calibration for Red Giants Based on the Colour–Magnitude Diagrams of Galactic Clusters. III. Calibration with 2MASS

2013 ◽  
Vol 30 ◽  
Author(s):  
S. Karaali ◽  
S. Bilir ◽  
E. Yaz Gökçe
Keyword(s):  
Magnitude Estimation ◽  
Absolute Magnitude ◽  
Red Giants ◽  
Derived Relations ◽  
Galactic Clusters ◽  
The Absolute ◽  
Standard Deviations ◽  
Red Giant ◽  
Absolute Magnitudes

AbstractWe present two absolute magnitude calibrations, MJ and MKs, for red giants with the colour–magnitude diagrams of five Galactic clusters with different metallicities, i.e. M92, M13, M71, M67, and NGC 6791. The combination of the absolute magnitudes of the red giant sequences with the corresponding metallicities provides calibration for absolute magnitude estimation for red giants for a given colour. The calibrations for MJ and MKs are defined in the colour intervals 1.3≤(V−J)0≤2.8 and 1.75≤(V−Ks)0≤3.80 mag, respectively, and they cover the metallicity interval −2.15≤[Fe/H]≤+0.37 dex. The absolute magnitude residuals obtained by the application of the procedure to another set of Galactic clusters lie in the intervals −0.08<ΔMJ≤+0.34 and -0.10< Δ MKs≤ +0.27 mag for MJ and MKs, respectively. The means and standard deviations of the residuals are 〈ΔMJ〉=0.137 and σMJ=0.080, and $〈 Δ MKs〉 =0.109 and σMKs=0.123 mag. The derived relations are applicable to stars older than 4 Gyr, the age of the youngest calibrating cluster.

scholarly journals The Luminosity Determination

1995 ◽  
Vol 10 ◽  
pp. 399-402
Author(s):  
A.E. Gómez ◽  
C. Turon
Keyword(s):  
Main Sequence ◽  
Small Volume ◽  
Absolute Magnitude ◽  
Fitting Procedure ◽  
Trigonometric Parallaxes ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes ◽  
Kinematical Data ◽  
Magnitude Determination

The Hertzprung-Russel (HR) diagram luminosity calibration relies basically on three kinds of data: trigonometric parallaxes, kinematical data (proper motions and radial velocities) and cluster distances obtained by the zero-age main sequence fitting procedure. The most fundamental method to calculate the absolute magnitude is the use of trigonometric parallaxes, but up to now, accurate data only exist for stars contained in a small volume around the sun. Individual absolute magnitudes are obtained using trigonometric parallaxes or photometric and spectroscopic calibrations. In these calibrations the accuracy on the absolute magnitude determination ranges from ±0.m2 in the main sequence to ±0m5 in the giant branch. On the other hand, trigonometric parallaxes, kinematical data or cluster distances have been used to make statistical calibrations of the absolute magnitude. The standard error on the mean absolute magnitude calibrations ranges from ±0m3 to ±0m6 on the mean sequence, from ±0m5 to ±0m7 on thegiant branch and is of about 1mfor supergiants.Future improvements in the absolute magnitude determination will depend on the improvement of the basic data from the ground and space. A brief overview of the new available data is presented. In particular, the analysis of the first 30 months data of the Hipparcos mission (H30) (from the 37 months data of the whole mission) allows to perform a statistical evaluation of the improvements expected in the luminosity determination.

scholarly journals The Parallaxes of U Gem Variables

1979 ◽  
Vol 53 ◽  
pp. 494-494
Author(s):  
Karl W. Kamper
Keyword(s):  
Confidence Level ◽  
Absolute Magnitude ◽  
Weighted Mean ◽  
Quiescent Phase ◽  
A Value ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes

An Allegheny parallax series of SS Cyg, consisting of 52 exposures obtained on 15 nights, was recently measured on the PDS microphotometer at the David Dunlap Observatory, and a value of (m.e.) derived for the absolute parallax. This is close to the mean of the two previous discordant measures for this star given in the table below. The weighted mean of the three determinations implies that the absolute magnitude, at quiescent phase, of the star is between 7.0 and 9.0 formally at a 90% confidence level. Recent parallax determinations made at Lick by Vasilevskls et al. (1975) for three other stars, listed below along with the Mt. Wilson value for U Gem, imply even fainter absolute magnitudes.

Observational selection and statistics of asteroids

1974 ◽  
Vol 22 ◽  
pp. 35-38
Author(s):  
T. Kiang
Keyword(s):  
Elementary Theory ◽  
Absolute Magnitude ◽  
Probabilistic Interpretation ◽  
Keplerian Motion ◽  
Observational Selection ◽  
Statistical Studies ◽  
The Mean ◽  
The Absolute ◽  
Osculating Elements ◽  
Elliptical Motion

In statistical studies of asteroids we usually deal with the osculating elementsa, e, π, i, Ω, and either the mean opposition magnitudem0or the absolute magnitudeg. We deliberately overlook the remaining osculating element, the mean anomaly at epoch, because we are not normally interested in the relatively fast changes in the complexion of the system brought about by the Keplerian motion; rather, we are concerned with the average complexion where each asteroid is replaced by a ring with aline densityρinversely proportional to the orbital speed. As is well known, Gauss used such rings to calculate secular inequalities, but here we give them a probabilistic interpretation:ρ. dλ is to be taken as the probability that an asteroid with given values of the elements is found in some particular range dλ of heliocentric longitude. We therefore putwhere dMis the interval in the mean anomaly corresponding to dλ. The function ρ is known from elementary theory of elliptical motion, but is rather complicated to write out explicitly.

Scaling Apparent Distance in a Large Open Field: Some New Data

1983 ◽  
Vol 56 (1) ◽  
pp. 135-138 ◽  
Author(s):  
José Aparecido Da Silva ◽  
Cleuza Beatriz Da Silva
Keyword(s):  
Standard Deviation ◽  
Open Field ◽  
Power Function ◽  
Magnitude Estimation ◽  
Apparent Distance ◽  
Physical Distance ◽  
Power Functions ◽  
The Mean

Judged distance in a large open field, scaled by the method of magnitude estimation, is related to physical distance by a power function with an exponent smaller than unity. The exponents obtained with two ranges of distance were not affected by the availability of a standard. The mean exponent for all 80 individual power functions was 0.86, with a standard deviation of 0.11.

scholarly journals A New Procedure for the Photometric Parallax Estimation

2003 ◽  
Vol 20 (3) ◽  
pp. 270-278 ◽  
Author(s):  
S. Karaali ◽  
Y. Karataş ◽  
S. Bilir ◽  
S. G. Ak ◽  
E. Hamzaoğlu
Keyword(s):  
Main Sequence ◽  
Large Range ◽  
Absolute Magnitude ◽  
Colour Index ◽  
Ultraviolet Excess ◽  
Magnitude Diagram ◽  
Single Colour ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes

AbstractWe present a new procedure for photometric parallax estimation. The data for 1236 stars provide calibrations between the absolute magnitude offset from the Hyades main-sequence and the ultraviolet-excess for eight different (B–V)0 colour-index intervals, (0.3 0.4), (0.4 0.5), (0.5 0.6), (0.6 0.7), (0.7 0.8), (0.8 0.9), (0.9 1.0) and (1.0 1.1). The mean difference between the original and estimated absolute magnitudes and the corresponding standard deviation are rather small, +0.0002 and ±0.0613 mag. The procedure has been adapted to the Sloan photometry by means of colour equations and applied to a set of artificial stars with different metallicities. The comparison of the absolute magnitudes estimated by the new procedure and the canonical one indicates that a single colour–magnitude diagram does not supply reliable absolute magnitudes for stars with large range of metallicity.

Satellite Estimates and Shipboard Observations of Downward Radiative Fluxes at the Ocean Surface

2008 ◽  
Vol 25 (3) ◽  
pp. 429-441 ◽  
Author(s):  
G. Guo ◽  
J. A. Coakley
Keyword(s):  
Radiant Energy ◽  
Absolute Magnitude ◽  
Weather Data ◽  
Radiative Fluxes ◽  
Oregon Coast ◽  
The Mean ◽  
The Absolute ◽  
Mean Differences ◽  
The Times ◽  
Longwave Flux

Abstract Clouds and the Earth’s Radiant Energy System (CERES) uses a suite of instruments on the Terra and Aqua satellites combined with analyzed weather data and information on surface conditions to estimate surface radiative fluxes. CERES estimates for the Terra satellite were compared with measurements of the surface radiative fluxes collected with the research vessels (RVs) Wecoma and Thomas G. Thompson radiometers for cruises off the Oregon coast undertaken during 2000–03. To assess the shipboard measurements, the radiometer observations were analyzed to identify cloud-free conditions characterized by ∼1–2 h of relatively stable radiative fluxes. Fluxes for the cloud-free conditions were compared with those calculated using profiles of temperature and humidity from analyzed meteorological fields for the times and locations of the measurements and broadband radiative transfer models. For summertime conditions along the Oregon coast, and assuming a marine aerosol having 0.55-μm optical depth of 0.05, modeled and observed values of the shortwave flux agreed to within 1%–2%. Similar comparisons for the downward cloud-free longwave flux were within 1%–3%. This agreement also held for the CERES surface radiative flux estimates with CERES cloud-free fields of view for ocean scenes within 50 km of the ship being compared with 30-min averages of the shipboard measurements centered on the times of the Terra overpass. Using the CERES observations to identify cloud-free conditions for the Wecoma revealed that in some cases the shipboard measurements of the shortwave flux varied erratically. Criteria were adopted to avoid such behavior, yielding periods in which the surface radiative fluxes were reasonably stable for a range of cloud-free and cloudy conditions. With the criteria applied, the absolute magnitude of the mean differences between the shipboard measurements and the CERES estimates for the downward shortwave flux were within 2%, with RMS differences less than 6% within each month of CERES–shipboard matchups. The absolute magnitude of the mean differences for the downward longwave flux was less than 2%, with RMS differences less than 5%.

Notizen: The Thermoelectric Power of Liquid Zinc

1965 ◽  
Vol 20 (8) ◽  
pp. 1081-1082 ◽  
Author(s):  
Alar Randsalu ◽  
Arnold Lunden
Keyword(s):  
Standard Deviation ◽  
Thermoelectric Power ◽  
Absolute Temperature ◽  
Liquid Zinc ◽  
Temperature Range ◽  
The Mean ◽  
The Absolute

The thermoelectric power of the cell W(s)/Zn(1)/W(s) was measured over the temperature range 465 — 711°C, and the absolute thermoelectric power of zinc was found to be S = — 0.164 + 1.298 · 10—3 Tm μV/degr. where Tm is the mean absolute temperature. The standard deviation of the measurements was 0.12 /μV/degr.

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