Use math symbol from different font

Question

I'd like to produce a "⋆" operator symbol with rather narrow points, resembling an asterisk, as seen in the Wikipedia page on cross-correlation:

If I use the default math font (Latin Modern Math), the command \star produces exactly what I'm looking for (and seems to be what this Wikipedia page is using). But I'd much prefer to continue using the newtxmath package, which in this case produces something more resembling a regular pentagram, similar to the one seen in Wolfram Mathworld:

Is there a way to have the \star command write a character in the default math font while using the newtxmath package elsewhere?

Answer 1

In the modern toolchain, with unicode-math, you can load a symbol from another math font with the range= option of \setmathfont:

\usepackage{unicode-math}
\defaultfontfeatures{ Scale=MatchLowercase, Ligatures=TeX }
\setmainfont{TeX Gyre Termes}[Scale=1.0]
\setmathfont{TeX Gyre Termes Math}
\setmathfont{Latin Modern Math}[range=\star]

Answer 2

You could borrow the \star from Latin Modern.

\documentclass[11pt]{article}
\usepackage{newtxtext}
\usepackage{newtxmath}
\DeclareSymbolFont{LMletters}{OML}{lmm}{m}{it}
\DeclareMathSymbol{\lmstar}{\mathbin}{LMletters}{63}
\begin{document}
\( f \star g \)

\( f \lmstar g \)
\end{document}

Answer 3

Update 1: after the correct comment of @Vincent

After many attemps and looked the manual of MnSymbol I have taken all the fonts of type MnSymbolC

etc...and with \DeclareMathSymbol{\thinstar}{\mathbin}{MnSyC}{134} I have obtained only the \thinstar operator (code 134).

\documentclass[a4paper,12pt]{article}
\usepackage{newtxtext}
\usepackage{newtxmath}
\DeclareFontFamily{U} {MnSymbolC}{}

\DeclareFontShape{U}{MnSymbolC}{m}{n}{
<-6> MnSymbolC5
<6-7> MnSymbolC6
<7-8> MnSymbolC7
<8-9> MnSymbolC8
<9-10> MnSymbolC9
<10-12> MnSymbolC10
<12-> MnSymbolC12}{}
\DeclareFontShape{U}{MnSymbolC}{b}{n}{
<-6> MnSymbolC-Bold5
<6-7> MnSymbolC-Bold6
<7-8> MnSymbolC-Bold7
<8-9> MnSymbolC-Bold8
<9-10> MnSymbolC-Bold9
<10-12> MnSymbolC-Bold10
<12-> MnSymbolC-Bold12}{}
\DeclareSymbolFont{MnSyC}         {U}  {MnSymbolC}{m}{n}
\SetSymbolFont{MnSyC} {bold}{U} {MnSymbolC}{b}{n}
\DeclareMathSymbol{\thinstar}{\mathbin}{MnSyC}{134}


\begin{document}
$\sum_{i=1}^n g\thinstar f \cup R$
or other
\[\sum \sigma_s\prod a_i\]
\end{document}

It seem that the symbols are all of newtxmath

if we compare with \sum and \prod of MnSymbol (for example),

---

I add some proposals....

    \documentclass[11pt]{article}
    \usepackage{newtxtext}
    \usepackage{newtxmath}
    \usepackage{MnSymbol}
    \usepackage{wasysym}
    
    
    \begin{document}
    \( f \star g \), \verb|classic star|
    
    \( f \mathbin{\filledstar}  g \), \verb|MnSymbol package|
    
    $f \mathrel{\thinstar} g $, \verb|MnSymbol package|
    
    $f \mathbin{\APLstar} g $, \verb|Table 330: wasysym APL Symbols|
    \end{document}