The Relation Between Absolute Magnitude and Reduced Proper Motion, and the Mean Errors in the Spectroscopic Absolute Magnitudes, for Stars of Spectral Classes G and K.

1939 ◽  
Vol 89 ◽  
pp. 10 ◽  
Author(s):  
Gustaf Stromberg
Keyword(s):  
Proper Motion ◽  
Absolute Magnitude ◽  
The Mean ◽  
Absolute Magnitudes

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 Hipparcos Positions of B/Be Stars on the HR Diagram

2000 ◽  
Vol 175 ◽  
pp. 117-128 ◽  
Author(s):  
Danielle Briot ◽  
Noel Robichon
Keyword(s):  
Spectral Type ◽  
Rotational Velocity ◽  
Absolute Magnitude ◽  
Be Stars ◽  
Class V ◽  
B Stars ◽  
Luminosity Class ◽  
The Mean ◽  
Absolute Magnitudes ◽  
Hipparcos Parallax

AbstractAbsolute magnitudes of Be and B stars are computed for each spectral type and luminosity class V and IV, using the Hipparcos parallax measurements. Some simulations have been carried out in order to estimate the effects which could bias the mean absolute magnitude calculations. As a result, only stars with σπ/π < 15% have been used. A first result is that B stars are fainter than previous estimations by about 0.5 magnitude on average. We then observe that on average Be stars are brighter than B stars of the same spectral type and this over-luminosity increases with the spectral type. A possible interpretation is proposed based on the fact that the rotational velocity of the late Be stars is near the critical rotational velocity.

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.

scholarly journals Absolute Magnitudes by Statistical Parallaxes

1978 ◽  
Vol 80 ◽  
pp. 49-52
Author(s):  
André Heck
Keyword(s):  
Maximum Likelihood ◽  
Absolute Magnitude ◽  
List Type ◽  
Solar Motion ◽  
The Mean ◽  
Absolute Magnitudes ◽  
The Individual ◽  
Image Position ◽  
Principle Of Maximum

Our algorithm for stellar luminosity calibrations (based on the principle of maximum likelihood) allows the calibration of relations of the type:Where n is the size of the sample at hand,Mi, are the individual absolute magnitudes,Cijare observational quantities (j = 1, …, N), andqjare the coefficients to be determined.If we put N = 1 and CiN= 1, we havethe mean absolute magnitude of the sample. As additional output, the algorithm provides us also with the dispersion in magnitude of the sample σM, the mean solar motion (U, V, W) and the corresponding velocity ellipsoid (σu, σV, σw).

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 Colour Transformations between BVRc and g′r′i′ Photometric Systems for Giant Stars

2014 ◽  
Vol 31 ◽  
Author(s):  
S. Ak ◽  
T. Ak ◽  
S. Karaali ◽  
S. Bilir ◽  
S. Tunçel Güçtekin ◽  
...  
Keyword(s):  
Absolute Magnitude ◽  
Temperature Data ◽  
Surface Gravity ◽  
National Observatory ◽  
Taurus Mountains ◽  
Giant Stars ◽  
Photometric Observations ◽  
The Mean ◽  
Effective Temperatures ◽  
Absolute Magnitudes

AbstractThe transformation equations from BVRc to g′r′i′ magnitudes and vice versa for the giants were established from a sample of 80 stars collected from Soubiran et al. (2010) with confirmed surface gravity (2 ⩽ logg (cm s− 2) ⩽ 3) at effective temperatures 4000 < Teff(K) < 16000. The photometric observations, all sample stars at g′r′i′ and 65 of them at BVRc, were obtained at TÜBİTAK National Observatory (TUG) 1m (T100) telescope, on the Taurus Mountains in Turkey. The MV absolute magnitudes of the giant stars were estimated from the absolute magnitude-temperature data for the giant stars by Sung et al. (2013) using the Teff from the intrinsic colours considered in this study. The transformation equations could be considered to be valid through the ranges of the following magnitudes and colours involved: 7.10 < V0 < 14.50, 7.30 < g′0 < 14.85, − 0.20 < (B − V)0 < 1.41, − 0.11 < (V − Rc)0 < 0.73, − 0.42 < (g′ − r′)0 < 1.15, and − 0.37 < (r′ − i′)0 < 0.47 mag. The transformations were successfully applied to the synthetic BVRc data of 427 field giants in order to obtain the g′r′i′ magnitudes and colours. Comparisons of these data with the g′r′i′ observations of giants in this study show that the mean residuals and standard deviations lie within [− 0.010, 0.042] and [0.028, 0.068] mag, respectively.

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.

scholarly journals Statistical Magnitude Analysis and Distance Determination of the Nearby F8V Stars

2014 ◽  
Vol 4 (4) ◽  
pp. 681-685
Author(s):  
H. R. Dwidar ◽  
A. Sharaf
Keyword(s):  
Absolute Magnitude ◽  
Mean Value ◽  
Descriptive Statistics ◽  
Percentage Error ◽  
Distance Determination ◽  
Nearby Stars ◽  
The Mean ◽  
Absolute Magnitudes ◽  
Frequency Functions

The present paper is of three folds. First, to provide some basic descriptive statistics parameters for the apparent and absolute magnitudes of the nearby stars of spectral type F8V stars. Second, to establish the frequency functions and of the absolute and apparent magnitudes for these stars. Third, to compute the distance r of these stars as a system assuming that they scatter around a mean absolute magnitude in a Gaussian distribution. The accuracy of the numerical results is satisfactory thus, the percentage error between r and the mean value is less than 0 .7%.

The Presence of the Wielen Dip in the Disk Stellar Luminosity Function

1991 ◽  
Vol 9 (2) ◽  
pp. 209-211
Author(s):  
Sang-Gak Lee
Keyword(s):  
Proper Motion ◽  
Luminosity Function ◽  
Absolute Magnitude ◽  
Motion Data ◽  
Magnitude Range ◽  
The Mean

AbstractThe disk stellar luminosity function has been redetermined by the mean absolute magnitude method, utilising the proper motion data of the LHS Catalog. The derived luminosity function shows a slightly deeper dip than that found by Wielen (1983) in the same magnitude range.

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.

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