STAR Atlas:PRO frequently asked questions - FAQs

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I understand Alpha Scorpius has a HotCompanion Star,
can STAR Atlas: PRO tell me if this is Correct and what Other
Information can it tell me about Alpha Scorpius ?

We�ll answer this question in two parts, first:

Yes � STAR Atlas: PRO can help,
And yes it is correct that a hot companion star is present.  Here is how readers can find out for themselves.

This is followed by part two of the answer, which describes what other information we can learn about Alpha Scorpius.

Alpha Scorpius is the brightest star in the constellation Scorpius and this star is also known as Antares.

To check if this star has a hot companion; -

1. Open Star Atlas: PRO.
2. Click on [Locate] on the main menu.
Under [Stellar Objects] (bottom centre),
 Click on [57 � Star Names].
5. Now click on [Find Star] (bottom left).
6. Now find Antares on the scrollable menu and click on it.
7. Click [Select] and this gives basic information about the name of the Star you selected (Antares in this example), but - ,
8. Click on [Display Information] (bottom centre) which then displays up to a page of data about the Star. You will see listed in the data is the Category D, hot companion, confirming that a hot companion star has previously been catalogued. Each Category in the list of Star Data defines the type of stellar data being displayed.

Key to Categories (as described in the STAR Atlas: PRO Manual).
C - Colours
D - Double and multiple stars
DYN - Dynamical parallaxes
G - Group membership
M - Miscellaneous
N - Star names
P - Polarisation
R - Stellar radii or diameters
RV - Radial and/or rotational velocities
S - Spectra
SB - Spectroscopic binaries
VAR � Variability

Part 2: what other information can STAR Atlas: PRO tell me about Alpha Scorpius ?

Continuing from above...

Now click the [Find Star in Hipparcos Catalogue] button (lower left), this will display the most accurate stellar data ever made available for all of the 100,000 brightest stars in the Night Sky. You will see on this display of data the precise stellar measurements of Alpha Scorpius taken by the Hipparcos Satellite. Including:

a. Precise Measurements include Magnitude,
b. Parallax,
c. Distance,
d. Mean BT and VT Magnitudes,
e. B-V Color,
f. Spectral Type,
g. Proper Motion,
h. And so much more.

But were not done yet! STAR Atlas: PRO still has a lot more to tell you about Alpha Scorpius.

10. Now click the [Double Star Data] button

STAR Atlas: PRO now displays another page of data that lists each star individually that makes up the Antares multiple star system. Upon further study of the stars listed you can see the first one is indeed Antares itself (listed as Component A) and says it is an M1 Spectral star, but the second star in the list (listed as Component B) is a fainter Magnitude 5.4 Star with a B3 Spectral Type at a Position Angle of 275 degrees with an Angular Separation of 2.9 arc seconds (the hot companion star).

You guessed ! STAR Atlas: PRO still has more to tell you yet, about Alpha Scorpius.

11. Click the [Close] button (lower right) and you�ll return to the Hipparcos Catalogue screen for Antares.
 Now, click the [Variable Star Data]

STAR Atlas: PRO now displays yet another page about the variability in the brightness of Antares, the Variability Type is displayed as �U� and upon reference to the STAR Atlas: PRO Manual this means it�s an Unsolved Variable Star ( the period/and or rate of change in Antares Magnitude is unsolved ) but for clarity here is the list or Variability Types:-

C - no variability detected, star is constant.
D - duplicity-induced variability
M - possible a micro-variable with a change in magnitude < 0.03.
P - periodic variable.
U - unsolved variable, which does not fit in other categories. 

You�ll need to now close each page of data which means choosing the [Close] button (or Alt-C on the keyboard) on each window until you return to the STAR Atlas: PRO desktop.

Now you have learned how to mine stellar data, enjoy exploring and learning about the other countless stars available in STAR Atlas: PRO. This should keep you busy a while!by Dr Ian Buttfield.

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