<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE article  PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "http://dtd.nlm.nih.gov/publishing/3.0/journalpublishing3.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" dtd-version="3.0" xml:lang="en" article-type="research article"><front><journal-meta><journal-id journal-id-type="publisher-id">IJAA</journal-id><journal-title-group><journal-title>International Journal of Astronomy and Astrophysics</journal-title></journal-title-group><issn pub-type="epub">2161-4717</issn><publisher><publisher-name>Scientific Research Publishing</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.4236/ijaa.2022.124020</article-id><article-id pub-id-type="publisher-id">IJAA-121928</article-id><article-categories><subj-group subj-group-type="heading"><subject>Articles</subject></subj-group><subj-group subj-group-type="Discipline-v2"><subject>Physics&amp;Mathematics</subject></subj-group></article-categories><title-group><article-title>
 
 
  New Probability Distributions in Astrophysics: X. Truncation and Mass-Luminosity Relationship for the Fr&#232;chet Distribution
 
</article-title></title-group><contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Lorenzo</surname><given-names>Zaninetti</given-names></name><xref ref-type="aff" rid="aff1"><sub>1</sub></xref><xref ref-type="corresp" rid="cor1"><sup>*</sup></xref></contrib></contrib-group><aff id="aff1"><label>1</label><addr-line>Physics Department, Turin, Italy</addr-line></aff><pub-date pub-type="epub"><day>25</day><month>10</month><year>2022</year></pub-date><volume>12</volume><issue>04</issue><fpage>347</fpage><lpage>362</lpage><history><date date-type="received"><day>30,</day>	<month>October</month>	<year>2022</year></date><date date-type="rev-recd"><day>20,</day>	<month>December</month>	<year>2022</year>	</date><date date-type="accepted"><day>23,</day>	<month>December</month>	<year>2022</year></date></history><permissions><copyright-statement>&#169; Copyright  2014 by authors and Scientific Research Publishing Inc. </copyright-statement><copyright-year>2014</copyright-year><license><license-p>This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/</license-p></license></permissions><abstract><p>
 
 
  The Fr&#232;chet distribution has aided the modelling of scientific data in many contexts. We demonstrate how it can be adapted to model astrophysical data. We analyze the truncated version of the Fr&#232;chet distribution deriving the probability density function (PDF), the distribution function, the average value, the 
  <em>r</em>th moment about the origin, the median, the random generation of values and the maximum likelihood estimator, which allows us to derive the two unknown parameters. This first PDF in the regular and truncated version is then applied to model the mass of the stars. A canonical transformation from the mass to the luminosity allows us to derive a new PDF, which is derived in its regular and truncated version. Finally, we apply this new PDF model on the distribution in luminosity of NGC 2362.
 
</p></abstract><kwd-group><kwd>Stars: Normal</kwd><kwd> Stars: Luminosity Function</kwd><kwd> Mass Function Stars: Statistics</kwd></kwd-group></article-meta></front><body><sec id="s1"><title>1. Introduction</title><p>The Fr&#232;cet distribution, after [<xref ref-type="bibr" rid="scirp.121928-ref1">1</xref>] , was first applied for the particle size distribution in powdered coal [<xref ref-type="bibr" rid="scirp.121928-ref2">2</xref>] . We report some efforts, among others, to derive the parameters of the Fr&#232;cet distribution: [<xref ref-type="bibr" rid="scirp.121928-ref3">3</xref>] analyzed a quick estimator that differs from the matching moments method and the maximum likelihood estimator (MLE); [<xref ref-type="bibr" rid="scirp.121928-ref4">4</xref>] analyzed the MLE and the probability weighted moment estimation; and [<xref ref-type="bibr" rid="scirp.121928-ref5">5</xref>] explored the MLE, the method of matching moments, the percentile estimators, the L-moments, the ordinary and weighted least squares, the maximum product of spacing and the maximum goodness-of-fit estimators. The applications cover inter-facial damage in microelectronic packages and the material properties of constituent particles in an aluminum alloy [<xref ref-type="bibr" rid="scirp.121928-ref6">6</xref>] ; the series of annual 1-day maximum rainfall [<xref ref-type="bibr" rid="scirp.121928-ref7">7</xref>] ; and the total monthly rainfall [<xref ref-type="bibr" rid="scirp.121928-ref5">5</xref>] . The case of the Fr&#232;cet distribution truncated at the right was introduced by [<xref ref-type="bibr" rid="scirp.121928-ref8">8</xref>] and that of the double truncation was carefully analyzed in [<xref ref-type="bibr" rid="scirp.121928-ref9">9</xref>] .</p><p>The rest of this paper is structured as follows. It first reviews the two parameters of the Fr&#232;cet distribution in the interval [ 0, ∞ ] , see Section 2, and then explores the bi-truncated case in Section 3. Section 4 transforms the standard and the truncated Fr&#232;chet distribution in mass into distributions in luminosity according to the well-known mass-luminosity relationship. Finally, the astrophysical applications to mass and luminosity for stars are reported in Section 5.</p></sec><sec id="s2"><title>2. Regular Case</title><p>Let X be a random variable defined in [ 0, ∞ ] ; the two parameter Fr&#232;cet distribution function (DF), F ( x ) , is</p><p>F ( x ; b , α ) = e − ( x b ) − α , (1)</p><p>where b and α , both positive, are the scale and the shape parameters, respectively, see [<xref ref-type="bibr" rid="scirp.121928-ref1">1</xref>] . The probability density function (PDF), f ( x ) , is</p><p>f ( x ; b , α ) = ( x b ) − α α   e − ( x b ) − α x . (2)</p><p>We now introduce</p><p>G A M M A r = Γ ( α − r α ) , (3)</p><p>where r is an integer and Γ ( z ) is the gamma function, which is defined as</p><p>Γ ( z ) = ∫ 0 ∞     e − t t z − 1 d t . (4)</p><p>The average value or mean, μ , is defined for α &gt; 1</p><p>μ ( b , α ) = b Γ 1 , (5)</p><p>the variance, σ 2 , is defined for α &gt; 2</p><p>σ 2 ( b , α ) = b 2 ( − Γ 1 2 + Γ 2 ) , (6)</p><p>the skewness is defined for α &gt; 3</p><p>skewness ( b , α ) = 2 Γ 1 3 − 3 Γ 2 Γ 1 + Γ 3 ( − Γ 1 2 + Γ 2 ) 3 2 , (7)</p><p>the kurtosis is defined for α &gt; 4</p><p>kurtosis ( b , α ) = − 3 Γ 1 4 + 6 Γ 1 2 Γ 2 − 4 Γ 1 Γ 3 + Γ 4 ( − Γ 1 2 + Γ 2 ) 2 , (8)</p><p>and the rth moment about the origin, μ ′ r , is defined for α &gt; r</p><p>μ ′ r ( b , α ) = b r Γ r . (9)</p><p>The median, q 1 / 2 , is at</p><p>q 1 / 2 ( b , α ) = ln ( 2 ) − 1 α b , (10)</p><p>and the mode is at</p><p>mode ( b , α ) = ( 1 + α ) − 1 α α 1 α b . (11)</p><p>Random generation of the Fr&#232;cet variate X is given by</p><p>X : b , α ≈ ( − ln ( R ) ) − 1 α b , (12)</p><p>where R is the unit rectangular variate.</p><p>The two parameters b and α can be derived by the numerical solution of the two following equations, which arise from the maximum likelihood estimator (MLE),</p><p>α ( − ( ∑ i = 1 n ( x i b ) − α ) + n ) b = 0 , (13a)</p><p>n ln ( b ) + n α + ∑ i = 1 n ( ( x i b ) − α ln ( x i b ) − ln ( x i ) ) = 0, (13b)</p><p>where x i are the elements of the experimental sample with i varying between 1 and n.</p></sec><sec id="s3"><title>3. The Truncated Fr&#232;cet Distribution</title><p>Let X be a random variable defined in [ x l , x u ] ; the truncated two-parameter Fr&#232;cet DF, F T ( x ) , is</p><p>F T ( x ; b , α , x l , x u ) = − e − x − α b α + e − x l − α b α − e − x u − α b α + e − x l − α b α , (14)</p><p>and the PDF, f T ( x ) , is</p><p>f T ( x ; b , α , x l , x u ) = ( x b ) − α α   e − ( x b ) − α x ( e − ( x u b ) − α − e − ( x l b ) − α ) . (15)</p><p>We now present two different formulae for the rth moment about the origin, μ ′ r : the first is</p><p>μ ′ r ( b , α , x l , x u ) = b r ( Γ ( α − r α , ( x l b ) − α ) − Γ ( α − r α , ( x u b ) − α ) ) − e − x u − α b α + e − x l − α b α , (16)</p><p>where</p><p>Γ ( a , z ) = ∫ z ∞     t a − 1 e − t d t , (17)</p><p>is the upper incomplete gamma function, see formula (8) in [<xref ref-type="bibr" rid="scirp.121928-ref9">9</xref>] and the second formula is</p><p>μ ′ r ( b , α , x l , x u ) = 1 ( α − r ) ( 2 α − r ) ( 3 α − r ) ( e − x u − α b α − e − x l − α b α )   &#215; ( − α ( − b − α + r 2 x l r 2 + α e − x l − α b α 2 ( − 2 α + r ) 2 M 2 α − r 2 α , 3 α − r 2 α ( x l − α b α )   + b − α + r 2 x u r 2 + α e − x u − α b α 2 ( − 2 α + r ) 2 M 2 α − r 2 α , 3 α − r 2 α ( x u − α b α )   + α ( e − x l − α b α 2 ( x l r 2 + α ( − 2 α + r ) b − α + r 2 − α   b r 2 x l r 2 ) M − r 2 α , 3 α − r 2 α ( x l − α b α )   + e − x u − α b α 2 M − r 2 α , 3 α − r 2 α ( x u − α b α ) ( − x u r 2 + α ( − 2 α + r ) b − α + r 2 + x u r 2 α b r 2 ) ) ) ) , (18)</p><p>where M μ ,   ν ( z ) is the Whittaker M function, see [<xref ref-type="bibr" rid="scirp.121928-ref10">10</xref>] . The variance can be evaluated with the usual formula</p><p>σ 2 ( b , α , x l , x u ) = μ ′ 2 ( b , α , x l , x u ) − ( μ ′ 1 ( b , α , x l , x u ) ) 2 , (19)</p><p>the median is at</p><p>q 1 / 2 ( b , α , x l , x u ) = b ( − ln ( e − x l − α b α 2 + e − x u − α b α 2 ) ) − 1 α , (20)</p><p>and the mode is at the same position as the regular case, see Equation (11). In the truncated case the mean and the variance are defined for α &gt; 0 , see <xref ref-type="fig" rid="fig1">Figure 1</xref> and <xref ref-type="fig" rid="fig2">Figure 2</xref>.</p><p>The random generation of the truncated Fr&#232;cet variate X is given by</p><p>X : b , α , x l , x u ≈ b ( − ln ( − R   e − x l − α b α + R   e − x u − α b α + e − x l − α b α ) ) − 1 α . (21)</p><p>The four parameters x l , x u , b and α can be obtained in the following way. Consider a sample X = x 1 , x 2 , ⋯ , x n and let x ( 1 ) ≥ x ( 2 ) ≥ ⋯ ≥ x ( n ) denote their order statistics, so that x ( 1 ) = max ( x 1 , x 2 , ⋯ , x n ) , x ( n ) = min ( x 1 , x 2 , ⋯ , x n ) . The first two parameters x l and x u are</p><p>x l = x ( n ) ,   x u = x ( 1 ) . (22)</p><p>The MLE allows us to derive the two remaining parameters b and α from the experimental sample</p><p>n α b + n ( ( x u b ) − α α   e − ( x u b ) − α b − ( x l b ) − α α   e − ( x l b ) − α b ) ( e − ( x u b ) − α − e − ( x l b ) − α ) ( − e − ( x u b ) − α + e − ( x l b ) − α ) 2   + ∑ i = 1 n ( − ( x i b ) − α α b ) = 0, (23a)</p><p>n ln ( b ) + n α + n ( − ( x u b ) − α ln ( x u b ) e − ( x u b ) − α + ( x l b ) − α ln ( x l b ) e − ( x l b ) − α ) ( e − ( x u b ) − α − e − ( x l b ) − α ) ( − e − ( x u b ) − α + e − ( x l b ) − α ) 2   + ∑ i = 1 n ( − ln ( x i ) + ( x i b ) − α ln ( x i b ) ) = 0. (23b)</p></sec><sec id="s4"><title>4. The Mass-Luminosity Relationship</title><p>The mass-luminosity relationship for the stars is well established from both a theoretical point of view, L ∝ M 3 or L ∝ M 4 , see [<xref ref-type="bibr" rid="scirp.121928-ref11">11</xref>] , and from an observational point of view, L ∝ M 3.43 in the case of MAIN,V; see [<xref ref-type="bibr" rid="scirp.121928-ref12">12</xref>] for further details. We therefore introduce the following transformation for our PDFs</p><p>L = c   M β , (24)</p><p>where L is the luminosity of a star, M is the mass of the star, and c and β are two theoretical parameters. This transformation implies</p><p>M = ( L c ) 1 β , (25a)</p><p>d M = d L   L 1 − β β c − 1 β β . (25b)</p><sec id="s4_1"><title>4.1. Fr&#232;chet M − L Distribution</title><p>To stress the astrophysical environment, we consider the change of variable x = M , the mass, in Equation (2) for the Fr&#232;chet PDF</p><p>f ( M ; b , α ) = ( M b ) − α α   e − ( M b ) − α M . (26)</p><p>To obtain a PDF in luminosity, L, we apply the transformation (24)</p><p>f M L ( L ; b , α , c , β ) = L − α − β β c α β b α α   e − L − α β c α β b α β , (27)</p><p>where the suffix ML means mass-luminosity relationship. The DF is</p><p>F M L ( L ; b , α , c , β ) = e − L − α β c α β b α , (28)</p><p>the average value is defined for α &gt; β</p><p>μ M L ( b , α , c , β ) = b β c Γ ( α − β α ) , (29)</p><p>the variance is defined for α &gt; 2   β</p><p>σ M L 2 ( b , α , c , β ) = b 2 β c 2 Γ ( − 2 β + α α ) − b 2 β c 2 Γ ( α − β α ) 2 , (30)</p><p>the rth moment about the origin is defined for α &gt; r   β</p><p>μ ′ M L ( b , α , c , β , r ) = b β r c r Γ ( − β r + α α ) , (31)</p><p>the mode is at</p><p>mode ( b , α , c , β ) M L = b β c ( α + β ) − β α α β α , (32)</p><p>the median is at</p><p>q M L ( b , α , c , β ) = b β c ln ( 2 ) − β α , (33)</p><p>and the random generation of the M − L Fr&#232;cet variate X is given by</p><p>X : b , α , c , β ≈ b β c ( − ln ( R ) ) − β α . (34)</p><p>The astrophysical parameter β is constant and the three parameters b, α and c can be derived by the numerical solution of the following equations which arise from MLE</p><p>− α ( c α β ( ∑ i = 1 n x i − α β ) b α − n ) b = 0, (35a)</p><p>( ∑ i = 1 n ( b α c α β ( − β ln ( b ) + ln ( x i ) − ln ( c ) ) x i − α β − ln ( x i ) ) ) α + n ( ln ( b ) α β + α ln ( c ) + β ) α β = 0, (35b)</p><p>− α ( c α β ( ∑ i = 1 n x i − α β ) b α − n ) β c = 0. (35c)</p></sec><sec id="s4_2"><title>4.2. The Truncated Fr&#232;chet M − L Distribution</title><p>The starting point is Equation (15) for the truncated Fr&#232;chet PDF with the variable x replaced by the mass. We apply the transformation (24) and the truncated Fr&#232;chet M − L PDF is</p><p>f M L T ( L ; b , α , c , β , L l , L u ) = L − α − β β c α β b α α   e − L − α β c α β b α β ( e − L u − α β c α β b α − e − L l − α β c α β b α ) , (36)</p><p>where L , L l and L u are the luminosity, the lower luminosity and the upper luminosity; the suffix MLT denotes mass-luminosity relationship. The DF is</p><p>F M L T ( L ; b , α , c , β , L l , L u ) = e − L − α β c α β b α e − L u − α β c α β b α − e − L l − α β c α β b α . (37)</p><p>The rth moment about the origin is</p><p>μ ′ r ( b , α , c , β , L l , L u ) = b β r c r ( Γ ( − β r + α α , L l − α β c α β b α ) − Γ ( − β r + α α , L u − α β c α β b α ) ) − e − L u − α β c α β b α + e − L l − α β c α β b α , (38)</p><p>the median is at</p><p>q 1 / 2 ( b , α , c , β , L l , L u ) = b β c ( − ln ( e − L u − α β c α β b α 2 − e − L l − α β c α β b α 2 ) ) − β α , (39)</p><p>the mode is at</p><p>mode ( b , α , c , β , L l , L u ) = b β ( α + β ) − β α α β α c , (40)</p><p>and the random generation of the variate is given by</p><p>X : b , α , c , β , L l , L u ≈ b β c ( − ln ( − R ( − e − L u − α β c α β b α + e − L l − α β c α β b α ) ) ) − β α . (41)</p><p>The parameter β is fixed by the astrophysics and the three parameters b , α , c are obtained by solving the following equations that arise from MLE</p><p>n α b + n ( L u − α β c α β b α α   e − L u − α β c α β b α b − L l − α β c α β b α α   e − L l − α β c α β b α b ) ( e − L u − α β c α β b α − e − L l − α β c α β b α ) ( − e − L u − α β c α β b α + e − L l − α β c α β b α ) 2   + ∑ i = 1 n ( − x i − α β c α β b α α b ) = 0, (42a)</p><p>n ln ( c ) β + n ln ( b ) + n α + C 2   + ∑ i = 1 n ( − ln ( x i ) β + x i − α β ln ( x i ) c α β b α β − x i − α β c α β ln ( c ) b α β − x i − α β c α β b α ln ( b ) ) = 0, (42b)</p><p>n α β c + n ( L u − α β c α β α   b α e − L u − α β c α β b α β c − L l − α β c α β α   b α e − L l − α β c α β b α β c ) ( e − L u − α β c α β b α − e − L l − α β c α β b α ) ( − e − L u − α β c α β b α + e − L l − α β c α β b α ) 2   + ∑ i = 1 n ( − x i − α β c α β α   b α β c ) = 0, (42c)</p><p>where</p><p>C 2 = 1 ( e − L u − α β c α β b α − e − L l − α β c α β b α ) 2 β &#215; n   c α β b α ( ln ( b ) e − L u − α β c α β b α L u − α β β   − ln ( b ) e − L l − α β c α β b α L l − α β β + ln ( c ) e − L u − α β c α β b α L u − α β − ln ( c ) e − L l − α β c α β b α L l − α β   − e − L u − α β c α β b α L u − α β ln ( L u ) + e − L l − α β c α β b α L l − α β ln ( L l ) ) ( e − L u − α β c α β b α − e − L l − α β c α β b α ) . (43)</p></sec></sec><sec id="s5"><title>5. Astrophysical Applications</title><p>This section reviews some formulae that are useful in the conversion from the magnitude to the luminosity of a star, the adopted statistical tests, the application of the obtained results to the IMF for stars and the reliability of M − L relationship for NGC 2362.</p><sec id="s5_1"><title>5.1. Useful Formulae</title><p>The conversion from apparent magnitude, m, to absolute magnitude, M, is given by</p><p>M = m + 5 − 5 ln ( D ) ln ( 10 ) , (44)</p><p>where D is the distance in pc and ln is the natural logarithm. The conversion from absolute magnitude to luminosity L is</p><p>L L ⊙ = 10 0.4 M ⊙ − 0.4 M , (45)</p><p>where L ⊙ and M ⊙ are the solar luminosity and absolute magnitude in the considered astronomical band, see Appendix A.4 in [<xref ref-type="bibr" rid="scirp.121928-ref13">13</xref>] .</p></sec><sec id="s5_2"><title>5.2. Statistics</title><p>The merit function χ 2 is computed according to the formula</p><p>χ 2 = ∑ i = 1 n ( T i − O i ) 2 T i , (46)</p><p>where n is the number of bins, T i is the theoretical value, and O i is the experimental value represented by the frequencies. The theoretical frequency distribution is given by</p><p>T i = N Δ x i p ( x ) , (47)</p><p>where N is the number of elements of the sample, Δ x i is the magnitude of the size interval, and p ( x ) is the PDF under examination. A reduced merit function χ r e d 2 is given by</p><p>χ r e d 2 = χ 2 / N F , (48)</p><p>where N F = n − k is the number of degrees of freedom, n is the number of bins, and k is the number of parameters. The goodness of the fit can be expressed by the probability Q, see equation 15.2.12 in [<xref ref-type="bibr" rid="scirp.121928-ref14">14</xref>] , which involves the number of degrees of freedom and χ 2 . According to [<xref ref-type="bibr" rid="scirp.121928-ref14">14</xref>] p. 658, the fit “may be acceptable” if Q &gt; 0.001 . The Akaike information criterion (AIC), see [<xref ref-type="bibr" rid="scirp.121928-ref15">15</xref>] , is defined by</p><p>AIC = 2 k − 2 ln ( L ) , (49)</p><p>where L is the likelihood function and k the number of free parameters in the model. We assume a Gaussian distribution for the errors. The likelihood function can then be derived from the χ 2 statistic L ∝ exp ( − χ 2 2 ) where χ 2 has been computed by equation (46), see [<xref ref-type="bibr" rid="scirp.121928-ref16">16</xref>] [<xref ref-type="bibr" rid="scirp.121928-ref17">17</xref>] . Now the AIC becomes</p><p>AIC = 2 k + χ 2 . (50)</p><p>The Kolmogorov-Smirnov test (K-S), see [<xref ref-type="bibr" rid="scirp.121928-ref18">18</xref>] [<xref ref-type="bibr" rid="scirp.121928-ref19">19</xref>] [<xref ref-type="bibr" rid="scirp.121928-ref20">20</xref>] , does not require the data to be binned. The K-S test, as implemented by the FORTRAN subroutine KSONE in [<xref ref-type="bibr" rid="scirp.121928-ref14">14</xref>] , finds the maximum distance, D, between the theoretical and the astronomical DF, as well as the significance level P<sub>KS</sub>; see formulas 14.3.5 and 14.3.9 in [<xref ref-type="bibr" rid="scirp.121928-ref14">14</xref>] . If P K S ≥ 0.1 , then the goodness of the fit is believable.</p></sec><sec id="s5_3"><title>5.3. The IMF for Stars</title><p>The first test is performed on NGC 2362 where the 271 stars have a range 1.47 M ⊙   ≥   M ≥ 0.11 M ⊙ , see [<xref ref-type="bibr" rid="scirp.121928-ref21">21</xref>] and CDS catalog J/MNRAS/384/675/table1. According to [<xref ref-type="bibr" rid="scirp.121928-ref22">22</xref>] , the distance of NGC 2362 is 1480 pc.</p><p>The second test is performed on the low-mass IMF in the young cluster NGC 6611, see [<xref ref-type="bibr" rid="scirp.121928-ref23">23</xref>] and CDS catalog J/MNRAS/392/1034. This massive cluster has an age of 2 - 3 Myr and contains masses from 1.5 M ⊙   ≥   M ≥ 0.02 M ⊙ . Therefore, the brown dwarfs (BD) region, ≈ 0.2 M ⊙ is covered. The third test is performed on the γ Velorum cluster where the 237 stars have a range 1.31 M ⊙   ≥   M ≥ 0.15 M ⊙ , see [<xref ref-type="bibr" rid="scirp.121928-ref24">24</xref>] and CDS catalog J/A + A/589/A70/table5. The fourth test is performed on the young cluster Berkeley 59 where the 420 stars have a range 2.24 M ⊙   ≥   M ≥ 0.15 M ⊙ , see [<xref ref-type="bibr" rid="scirp.121928-ref25">25</xref>] and CDS catalog J/AJ/155/44/table3. The results are presented in <xref ref-type="table" rid="table1">Table 1</xref> for the Fr&#232;chet distribution with two parameters and in <xref ref-type="table" rid="table2">Table 2</xref> for the truncated Fr&#232;chet distribution with four parameters, where the last column reports whether the results of the K-S test are better when</p><table-wrap id="table1" ><label><xref ref-type="table" rid="table1">Table 1</xref></label><caption><title> Numerical values of χ r e d 2 , AIC, probability Q, D, the maximum distance between theoretical and observed DF, and P<sub>KS</sub>, significance level, in the K-S test of the Fr&#232;chet distribution with two parameters for different astrophysical environments. The last column (F) indicates a P<sub>KS</sub> higher (Y) or lower (N) than that for the lognormal distribution. The number of linear bins, n, is 10</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >Cluster</th><th align="center" valign="middle" >parameters</th><th align="center" valign="middle" >AIC</th><th align="center" valign="middle" >χ r e d 2</th><th align="center" valign="middle" >Q</th><th align="center" valign="middle" >D</th><th align="center" valign="middle" >P<sub>KS</sub></th><th align="center" valign="middle" >F</th></tr></thead><tr><td align="center" valign="middle" >NGC 2362</td><td align="center" valign="middle" >b = 0.44, α = 1.825</td><td align="center" valign="middle" >81.58</td><td align="center" valign="middle" >9.69</td><td align="center" valign="middle" >1.49 &#215; 10<sup>−</sup><sup>13</sup></td><td align="center" valign="middle" >0.125</td><td align="center" valign="middle" >3.13 &#215; 10<sup>−</sup><sup>4</sup></td><td align="center" valign="middle" >N</td></tr><tr><td align="center" valign="middle" >NGC 6611</td><td align="center" valign="middle" >b = 0.165, α = 0.912</td><td align="center" valign="middle" >83.57</td><td align="center" valign="middle" >9.94</td><td align="center" valign="middle" >5.95 &#215; 10<sup>−</sup><sup>14</sup></td><td align="center" valign="middle" >0.15</td><td align="center" valign="middle" >1.43 &#215; 10<sup>−</sup><sup>4</sup></td><td align="center" valign="middle" >N</td></tr><tr><td align="center" valign="middle" >γ Velorum</td><td align="center" valign="middle" >b = 0.267, α = 2.572</td><td align="center" valign="middle" >23.7</td><td align="center" valign="middle" >2.46</td><td align="center" valign="middle" >0.015</td><td align="center" valign="middle" >0.046</td><td align="center" valign="middle" >0.68</td><td align="center" valign="middle" >Y</td></tr><tr><td align="center" valign="middle" >Berkeley 59</td><td align="center" valign="middle" >b = 0.319, α = 2.68</td><td align="center" valign="middle" >37.63</td><td align="center" valign="middle" >4.2</td><td align="center" valign="middle" >4.72 &#215; 10<sup>−</sup><sup>5</sup></td><td align="center" valign="middle" >5.1&#215;10<sup>−</sup><sup>2</sup></td><td align="center" valign="middle" >0.209</td><td align="center" valign="middle" >Y</td></tr></tbody></table></table-wrap><table-wrap id="table2" ><label><xref ref-type="table" rid="table2">Table 2</xref></label><caption><title> Numerical values of χ r e d 2 , AIC, probability Q, D, the maximum distance between theoretical and observed DF, and P<sub>KS</sub>, significance level, in the K-S test of the truncated Fr&#232;chet distribution with four parameters for different astrophysical environments. The last column (F) indicates a P<sub>KS</sub> higher (Y) or lower (N) than that for the lognormal distribution. The number of linear bins, n, is 10</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >Cluster</th><th align="center" valign="middle" >parameters</th><th align="center" valign="middle" >AIC</th><th align="center" valign="middle" >χ r e d 2</th><th align="center" valign="middle" >Q</th><th align="center" valign="middle" >D</th><th align="center" valign="middle" >P<sub>KS</sub></th><th align="center" valign="middle" >F</th></tr></thead><tr><td align="center" valign="middle" >NGC 2362</td><td align="center" valign="middle" >b = 0.604, α = 1.24, x<sub>l</sub> = 0.2, x<sub>u</sub> = 1.47</td><td align="center" valign="middle" >37.294</td><td align="center" valign="middle" >4.88</td><td align="center" valign="middle" >5.34 &#215; 10<sup>−</sup><sup>5</sup></td><td align="center" valign="middle" >0.077</td><td align="center" valign="middle" >0.07</td><td align="center" valign="middle" >N</td></tr><tr><td align="center" valign="middle" >NGC 6611</td><td align="center" valign="middle" >b = 0.66, α = 0.44, x<sub>l</sub> = 0.0189, x<sub>u</sub> = 1.46</td><td align="center" valign="middle" >25.7</td><td align="center" valign="middle" >2.95</td><td align="center" valign="middle" >7 &#215; 10<sup>−</sup><sup>3</sup></td><td align="center" valign="middle" >0.075</td><td align="center" valign="middle" >0.17</td><td align="center" valign="middle" >Y</td></tr><tr><td align="center" valign="middle" >γ Velorum</td><td align="center" valign="middle" >b = 0.2, α = 1.5, x<sub>l</sub> = 0.15, x<sub>u</sub> = 1.31</td><td align="center" valign="middle" >14.85</td><td align="center" valign="middle" >1.14</td><td align="center" valign="middle" >0.33</td><td align="center" valign="middle" >0.06</td><td align="center" valign="middle" >0.33</td><td align="center" valign="middle" >Y</td></tr><tr><td align="center" valign="middle" >Berkeley 59</td><td align="center" valign="middle" >b = 0.32, α = 2.58, x<sub>l</sub> = 0.16, x<sub>u</sub> = 2.24</td><td align="center" valign="middle" >35.13</td><td align="center" valign="middle" >4.52</td><td align="center" valign="middle" >1.36 &#215; 10<sup>−</sup><sup>4</sup></td><td align="center" valign="middle" >5.28 &#215; 10<sup>−</sup><sup>2</sup></td><td align="center" valign="middle" >0.185</td><td align="center" valign="middle" >Y</td></tr></tbody></table></table-wrap><p>compared to the Weibull distribution (Y) or worse (N).</p><p>As an example, the empirical DF visualized through histograms and the theoretical Fr&#232;chet DF for γ Velorum are reported in <xref ref-type="fig" rid="fig3">Figure 3</xref>.</p><p><xref ref-type="fig" rid="fig4">Figure 4</xref> displays the theoretical truncated Fr&#232;chet DF and the empirical DF for NGC 6611.</p></sec><sec id="s5_4"><title>5.4. M − L Relationship</title><p>We start with the sample in apparent magnitude for NGC 2362, see <xref ref-type="fig" rid="fig5">Figure 5</xref>. To have a sample in luminosity for NGC 2362, we convert the apparent magnitude in luminosity via formula (45); see <xref ref-type="fig" rid="fig6">Figure 6</xref>.</p><p>The data of <xref ref-type="fig" rid="fig6">Figure 6</xref> are now processed to obtain the parameters of the</p><p>M − L Fr&#232;cet distribution, see <xref ref-type="table" rid="table3">Table 3</xref>, and of the truncated M − L Fr&#232;cet distribution, see <xref ref-type="table" rid="table4">Table 4</xref>.</p><p><xref ref-type="fig" rid="fig7">Figure 7</xref> displays the theoretical luminosity M − L Fr&#232;chet DF and the empirical DF, and <xref ref-type="fig" rid="fig8">Figure 8</xref> displays the truncated M − L Fr&#232;chet DF.</p><table-wrap id="table3" ><label><xref ref-type="table" rid="table3">Table 3</xref></label><caption><title> Numerical values of χ r e d 2 , AIC, probability Q, D, the maximum distance between theoretical and observed DF, and P<sub>KS</sub>, significance level, in the K-S test of the M − L Fr&#232;cet distribution in luminosity with four parameters. The number of linear bins, n, is 20</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >Cluster</th><th align="center" valign="middle" >Parameters</th><th align="center" valign="middle" >AIC</th><th align="center" valign="middle" >χ r e d 2</th><th align="center" valign="middle" >Q</th><th align="center" valign="middle" >D</th><th align="center" valign="middle" >P<sub>KS</sub></th></tr></thead><tr><td align="center" valign="middle" >NGC 2362</td><td align="center" valign="middle" >b = 0.092,α = 2.48, c = 11.47, β = 2.45</td><td align="center" valign="middle" >23.17</td><td align="center" valign="middle" >0.948</td><td align="center" valign="middle" >0.511</td><td align="center" valign="middle" >0.154</td><td align="center" valign="middle" >3.93 &#215; 10<sup>−</sup><sup>6</sup></td></tr></tbody></table></table-wrap><table-wrap id="table4" ><label><xref ref-type="table" rid="table4">Table 4</xref></label><caption><title> Numerical values of χ r e d 2 , AIC, probability, Q, D, the maximum distance between theoretical and observed DF, and P<sub>KS</sub>, significance level, in the K-S test of the truncated M − L Fr&#232;cet distribution in luminosity with six parameters. The number of linear bins, n, is 20</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >Cluster</th><th align="center" valign="middle" >Parameters</th><th align="center" valign="middle" >AIC</th><th align="center" valign="middle" >χ r e d 2</th><th align="center" valign="middle" >Q</th><th align="center" valign="middle" >D</th><th align="center" valign="middle" >P<sub>KS</sub></th></tr></thead><tr><td align="center" valign="middle"  rowspan="2"  >NGC 2362</td><td align="center" valign="middle" >b = 0.097,α = 1.47, c = 7.56, β = 2.45</td><td align="center" valign="middle" >25.24</td><td align="center" valign="middle" >0.946</td><td align="center" valign="middle" >0.507</td><td align="center" valign="middle" >0.0341</td><td align="center" valign="middle" >0.903</td></tr><tr><td align="center" valign="middle" >L l = 1.15 &#215; 10 − 3 L ⊙ , L u = 0.55 L ⊙</td><td align="center" valign="middle" ></td><td align="center" valign="middle" ></td><td align="center" valign="middle" ></td><td align="center" valign="middle" ></td><td align="center" valign="middle" ></td></tr></tbody></table></table-wrap></sec></sec><sec id="s6"><title>6. Conclusions</title><p>The truncated distributions</p><p>We derived the PDF, the DF, the average value, the rth moment, the median, the expression to generate the random variate and the MLE for the truncated Fr&#232;cet distribution.</p><p>Astrophysical Applications</p><p>The application of this distribution to the IMF for stars gives better results than the lognormal distribution for two out of four samples, see <xref ref-type="table" rid="table1">Table 1</xref>. The truncated Fr&#232;cet distribution gives better results than the Fr&#232;cet distribution for two out of four samples, see <xref ref-type="table" rid="table1">Table 1</xref> and <xref ref-type="table" rid="table2">Table 2</xref>.</p><p>The results for the mass distribution of γ Velorum cluster compared with other distributions are reported in <xref ref-type="table" rid="table5">Table 5</xref>, in which the Fr&#232;cet distribution surprisingly produces the best results.</p><table-wrap id="table5" ><label><xref ref-type="table" rid="table5">Table 5</xref></label><caption><title> Numerical values of D, the maximum distance between theoretical and observed DF, and P<sub>KS</sub>, significance level, in the K-S test for different distributions in the case of γ Velorum cluster</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >Distribution</th><th align="center" valign="middle" >Reference</th><th align="center" valign="middle" >D</th><th align="center" valign="middle" >P<sub>KS</sub></th></tr></thead><tr><td align="center" valign="middle" >Fr&#232;cet</td><td align="center" valign="middle" >here</td><td align="center" valign="middle" >0.046</td><td align="center" valign="middle" >0.68</td></tr><tr><td align="center" valign="middle" >Weibull</td><td align="center" valign="middle" >[<xref ref-type="bibr" rid="scirp.121928-ref26">26</xref>]</td><td align="center" valign="middle" >0.14</td><td align="center" valign="middle" >6.6 &#215; 10<sup>−</sup><sup>5</sup></td></tr><tr><td align="center" valign="middle" >Truncated Weibull</td><td align="center" valign="middle" >[<xref ref-type="bibr" rid="scirp.121928-ref26">26</xref>]</td><td align="center" valign="middle" >0.063</td><td align="center" valign="middle" >0.29</td></tr><tr><td align="center" valign="middle" >Truncated Sujatha</td><td align="center" valign="middle" >[<xref ref-type="bibr" rid="scirp.121928-ref27">27</xref>]</td><td align="center" valign="middle" >0.0614</td><td align="center" valign="middle" >0.322</td></tr><tr><td align="center" valign="middle" >Truncated Lindley</td><td align="center" valign="middle" >[<xref ref-type="bibr" rid="scirp.121928-ref28">28</xref>]</td><td align="center" valign="middle" >0.064</td><td align="center" valign="middle" >0.269</td></tr><tr><td align="center" valign="middle" >Generalized gamma</td><td align="center" valign="middle" >[<xref ref-type="bibr" rid="scirp.121928-ref29">29</xref>]</td><td align="center" valign="middle" >0.11</td><td align="center" valign="middle" >5.7 &#215; 10<sup>−</sup><sup>3</sup></td></tr><tr><td align="center" valign="middle" >Truncated generalized gamma</td><td align="center" valign="middle" >[<xref ref-type="bibr" rid="scirp.121928-ref29">29</xref>]</td><td align="center" valign="middle" >0.105</td><td align="center" valign="middle" >9.38 &#215; 10<sup>−</sup><sup>3</sup></td></tr><tr><td align="center" valign="middle" >Lognormal</td><td align="center" valign="middle" >[<xref ref-type="bibr" rid="scirp.121928-ref30">30</xref>]</td><td align="center" valign="middle" >0.091</td><td align="center" valign="middle" >0.034</td></tr><tr><td align="center" valign="middle" >Truncated lognormal</td><td align="center" valign="middle" >[<xref ref-type="bibr" rid="scirp.121928-ref30">30</xref>]</td><td align="center" valign="middle" >0.0529</td><td align="center" valign="middle" >0.509</td></tr><tr><td align="center" valign="middle" >Gamma</td><td align="center" valign="middle" >[<xref ref-type="bibr" rid="scirp.121928-ref31">31</xref>]</td><td align="center" valign="middle" >0.145</td><td align="center" valign="middle" >7.6 &#215; 10<sup>−</sup><sup>5</sup></td></tr><tr><td align="center" valign="middle" >Truncated gamma</td><td align="center" valign="middle" >[<xref ref-type="bibr" rid="scirp.121928-ref31">31</xref>]</td><td align="center" valign="middle" >0.0812</td><td align="center" valign="middle" >0.0828</td></tr><tr><td align="center" valign="middle" >Beta</td><td align="center" valign="middle" >[<xref ref-type="bibr" rid="scirp.121928-ref32">32</xref>]</td><td align="center" valign="middle" >0.1</td><td align="center" valign="middle" >0.015</td></tr></tbody></table></table-wrap><p>The mass-luminosity relationship</p><p>We made a transformation that connects a pdf in mass into a pdf in luminosity, see Equation (24). The resulting distribution in luminosity has been applied to NGC 2362, see <xref ref-type="table" rid="table4">Table 4</xref>. <xref ref-type="fig" rid="fig7">Figure 7</xref> and <xref ref-type="fig" rid="fig8">Figure 8</xref> display the DF for the M − L Fr&#232;chet DF and the truncated M − L Fr&#232;chet DF. These results are compatible with L ∝ M 2.45 , which can be another way to confirm the M − L relationship.</p></sec><sec id="s7"><title>Conflicts of Interest</title><p>The author declares no conflicts of interest regarding the publication of this paper.</p></sec><sec id="s8"><title>Cite this paper</title><p>Lorenzo Zaninetti (2022) New Probability Distributions in Astrophysics: X. Truncation and Mass-Luminosity Relationship for the Fr&#232;chet Distribution. International Journal of Astronomy and Astrophysics, 12, 347-362. https://doi.org/10.4236/ijaa.2022.124020</p></sec></body><back><ref-list><title>References</title><ref id="scirp.121928-ref1"><label>1</label><mixed-citation publication-type="journal" xlink:type="simple"><name name-style="western"><surname>Fréchet</surname><given-names> M. </given-names></name>,<etal>et al</etal>. (<year>1927</year>)<article-title>Sur la loi de probabilité de l’écart maximum</article-title><source> Annales de la Société Polonaise de Mathématique</source><volume> 6</volume>,<fpage> 93</fpage>-<lpage>116</lpage>.<pub-id pub-id-type="doi"></pub-id></mixed-citation></ref><ref id="scirp.121928-ref2"><label>2</label><mixed-citation publication-type="other" xlink:type="simple">Rosin, P. and Rammler, E. (2012) The Laws Governing the Fineness of Powdered Coal. 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