<p>Yes. If you have the Hipparcos data from ftp (<a href="http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=I/239&amp;-to=3" rel="nofollow">http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=I/239&amp;-to=3</a>), you will have several data files.</p>

<p>In <code>hip_main.dat</code> you have a field <code>MultFlag</code> at position 347 that indicates whether the star is a double or multiple star:    </p>

<pre><code>Note on MultFlag: indicates that further details are given in the Double
     and Multiple Systems Annex:
     C : solutions for the components
     G : acceleration or higher order terms
     O : orbital solutions
     V : variability-induced movers (apparent motion arises from variability)
     X : stochastic solution (probably astrometric binaries with short period)
</code></pre>

<p>To determine whether the star is a double or multiple star system, look in one of the files for double star solutions. For instance in <code>h_dm_com.dat</code> there is a field at bytes 24-25 that gives the number of components (2 for double and >2 for multiple stars).</p>

<pre><code>24- 25  I2     ---     Ncomp    Number of components in this solution   (DCM2)
</code></pre>

<p>The Hipparcos number identifying the star can be found in bytes 43-48.</p>

<p>Of course this only works for multiple stars with orbital solutions.</p>

<p>For <strong>variability</strong>, three fields are provided in the main Hipparcos file:</p>

<pre><code>314-320  F7.2  d       Period    ? Variability period (days)              (H51)
     322  A1    ---     HvarType *[CDMPRU]? variability type               (H52)
     324  A1    ---     moreVar  *[12] Additional data about variability   (H53)
</code></pre>

<p>with two notes (NB. if <code>HvarType</code> is <code>C</code> then the star is constant, i.e. not variable!):</p>

<pre><code>Note on HvarType: Hipparcos-defined type of variability (a blank entry
     signifies that the entry could not be classified as variable or constant):
     C : no variability detected ("constant")
     D : duplicity-induced variability
     M : possibly micro-variable (amplitude &lt; 0.03mag)
     P : periodic variable
     R : V-I colour index was revised due to variability analysis
     U : unsolved variable which does not fall in the other categories
Note on moreVar: more data about periodic variability are provided
</code></pre>

<p>There are two additional files on variability: <code>hip_va_1.dat</code> and <code>hip_va_2.dat</code>, which provide information such as variable type (GCVS) and max and min magnitude and also the variable star name.
You can find a description of the variable type in the General Catalogue of Variable Stars (GCVS) in the file <code>vartype.txt</code> if you download the GCVS at <a href="http://cdsarc.u-strasbg.fr/viz-bin/Cat?B/gcvs" rel="nofollow">http://cdsarc.u-strasbg.fr/viz-bin/Cat?B/gcvs</a></p>

CC BY-SA 3.0
2015-04-17T12:51:11.083Z
Meant to add Variable stars as well, is that available from hipparcos?
MiscellaneousUser
CC BY-SA 3.0
2015-04-17T13:03:03.390Z
What is meant by Orbital Solutions?
MiscellaneousUser
CC BY-SA 3.0
2015-04-17T13:06:17.313Z
Yes on variable stars, see my edit of the answer.
Dieudonné
CC BY-SA 3.0
2015-04-17T13:09:36.313Z
Orbital solutions are used to calculate the orbit of one star in the binary with respect to the other star. They can be found in the file 'hip_dm_o.dat'.
Dieudonné
CC BY-SA 3.0
2015-04-17T07:54:28.190Z
2015-04-17T13:05:52.290Z
2015-04-17T13:05:52.290Z
Dieudonné
<p>The logic for double/multiple systems in Hipparcos is fairly complex.</p>
<p>Some good documentation is <a href="https://www.cosmos.esa.int/documents/532822/552851/vol1_all.pdf/99adf6e3-6893-4824-8fc2-8d3c9cbba2b5" rel="nofollow noreferrer">here</a> (large PDF) and <a href="https://www.cosmos.esa.int/documents/532822/553204/sect2_01.pdf/88f60038-085c-4cf0-9de0-42af104e8ae1" rel="nofollow noreferrer">here</a>.</p>
<p>Just looking at the <em>MultFlag</em> may not be enough. If I understand it correctly, some double/multiple stars, sharing the same CCDM identifier (field H55), appear as separate entries in Hipparcos. Many would want to consider all such entries sharing the same CCDM as belonging to the same system.</p>
<p>The CCDM id comes from a separate catalog of double/multiple stars. (It also comes from Hipparcos itself, which created new CCDM ids as part of its processing.)</p>

CC BY-SA 4.0
2022-03-21T17:51:02.773Z
2022-03-21T17:51:02.773Z
John
<p>Is there any way I can tell from Hipparcos catalog which stars are Binary/Multiple Stars and which are Variable stars?</p>

<star>
Variable and Multiple Stars in Hipparcos
MiscellaneousUser
# Variable and Multiple Stars in Hipparcos

(Asked by: username_0 on 2015-04-17)

Is there any way I can tell from Hipparcos catalog which stars are Binary/Multiple Stars and which are Variable stars?

**Tags:** star

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## 2 answers

### Answer by username_1 on 2015-04-17. Score: 3 | Accepted answer

Yes. If you have the Hipparcos data from ftp (http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=I/239&-to=3), you will have several data files.
In hip_main.dat you have a field MultFlag at position 347 that indicates whether the star is a double or multiple star:    
Note on MultFlag: indicates that further details are given in the Double
     and Multiple Systems Annex:
     C : solutions for the components
     G : acceleration or higher order terms
     O : orbital solutions
     V : variability-induced movers (apparent motion arises from variability)
     X : stochastic solution (probably astrometric binaries with short period)

To determine whether the star is a double or multiple star system, look in one of the files for double star solutions. For instance in h_dm_com.dat there is a field at bytes 24-25 that gives the number of components (2 for double and >2 for multiple stars).
24- 25  I2     ---     Ncomp    Number of components in this solution   (DCM2)

The Hipparcos number identifying the star can be found in bytes 43-48.
Of course this only works for multiple stars with orbital solutions.
For variability, three fields are provided in the main Hipparcos file:
314-320  F7.2  d       Period    ? Variability period (days)              (H51)
     322  A1    ---     HvarType *[CDMPRU]? variability type               (H52)
     324  A1    ---     moreVar  *[12] Additional data about variability   (H53)

with two notes (NB. if HvarType is C then the star is constant, i.e. not variable!):
Note on HvarType: Hipparcos-defined type of variability (a blank entry
     signifies that the entry could not be classified as variable or constant):
     C : no variability detected ("constant")
     D : duplicity-induced variability
     M : possibly micro-variable (amplitude < 0.03mag)
     P : periodic variable
     R : V-I colour index was revised due to variability analysis
     U : unsolved variable which does not fall in the other categories
Note on moreVar: more data about periodic variability are provided

There are two additional files on variability: hip_va_1.dat and hip_va_2.dat, which provide information such as variable type (GCVS) and max and min magnitude and also the variable star name.
You can find a description of the variable type in the General Catalogue of Variable Stars (GCVS) in the file vartype.txt if you download the GCVS at http://cdsarc.u-strasbg.fr/viz-bin/Cat?B/gcvs

> **Comments:**
> **username_0**: Meant to add Variable stars as well, is that available from hipparcos?  
> **username_0**: What is meant by Orbital Solutions?  
> **username_1**: Yes on variable stars, see my edit of the answer.  
> **username_1**: Orbital solutions are used to calculate the orbit of one star in the binary with respect to the other star. They can be found in the file 'hip_dm_o.dat'.  

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### Answer by username_2 on 2022-03-21. Score: 0

The logic for double/multiple systems in Hipparcos is fairly complex.

Some good documentation is [here](https://www.cosmos.esa.int/documents/532822/552851/vol1_all.pdf/99adf6e3-6893-4824-8fc2-8d3c9cbba2b5) (large PDF) and [here](https://www.cosmos.esa.int/documents/532822/553204/sect2_01.pdf/88f60038-085c-4cf0-9de0-42af104e8ae1).

Just looking at the *MultFlag* may not be enough. If I understand it correctly, some double/multiple stars, sharing the same CCDM identifier (field H55), appear as separate entries in Hipparcos. Many would want to consider all such entries sharing the same CCDM as belonging to the same system.

The CCDM id comes from a separate catalog of double/multiple stars. (It also comes from Hipparcos itself, which created new CCDM ids as part of its processing.)


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