Counting Nearby Stars

In my previous post, I casually stated that there are 61 stars in the region within 5 parsecs of the Sun -- at least according to the Gliese Catalog of Nearby Stars. I did not state where you could get that information for yourself. This short post describes how to figure this out for yourself. Here is my approach:

  • Get a copy of the Gliese Catalog here.
  • Look in the readme file here to understand the document format.
  • Many of these stars have common names that you can find .
  • Analyze the text file for the nearby stars in Excel like I did here.

My quick and dirty analysis shows that there are 61 stars within 5 parsecs of the Sun. I put together an Excel table but it is my second favorite software tool -- Mathcad is my favorite. I did add a couple of columns to the original Gliese columns: (1) a column of common names, and (2) the distances to the stars in light-years. The Gliese catalog just gives the milliarcseconds of parallax and I needed to convert the milliarcseconds to light-years using the following formula.

\displaystyle d[\text{light-years }\!\!]\!\!\text{ =}\frac{{{d}_{AU}}[\text{km }\!\!]\!\!\text{ }}{\frac{\pi \left[ \text{radians} \right]}{180{}^\circ }\cdot \frac{\theta [\text{milliarcseconds }\!\!]\!\!\text{ }\cdot \text{0}\text{.001}\left[ \frac{\text{arcseconds}}{\text{milliarcseconds}} \right]}{3600\left[ \frac{\text{arcseconds}}{\text{degree}} \right]}\cdot {{d}_{LightYear}}[\text{km }\!\!]\!\!\text{ }}

Here is the table I put together. I should note that new stars have been discovered since the Gliese table was put together (example). This is just a rough order of magnitude calculation (Fermi problem) and the results are good enough for what I am doing here.

Gliese Reference

Common Name

Distance (Light-Years)

Sun

Sun

0.00

GL551C

Proxima

4.24

GL559A

αCentauriA

4.37

GL559B

αCentauriB

4.37

GL699

Barnard's

6.00

GL406

Wolf359

7.82

GL411

Lalande21185

8.23

GL65A

BLCeti

8.59

GL65B

UVCeti

8.59

GL244A

SiriusA

8.60

GL244B

SiriusB

8.60

GL729

Ross154

9.59

GL905

Ross248

10.36

GL144

εEridani

10.70

GL447

Ross128

10.86

GL866A

Luyten789-6A

11.11

GL15A

Groombridge34A

11.30

GL15B

Groombridge34B

11.30

GL845A

εIndiA

11.32

GL820A

61CygniA

11.33

GL820B

61CygniB

11.33

GL725A

Struve2398A

11.43

GL725B

Struve2398B

11.43

GL71

tauCeti

11.44

GL280A

ProcyonA

11.44

GL280B

ProcyonB

11.44

GL887

Lacaille9352

11.50

GJ1111

DXCancri

11.86

GL54.1

YZCeti

12.23

GL273

Luyten's

12.37

GL825

Lacaille8760

12.65

GL191

Kapteyn's

12.66

GL860A

Kruger60A

12.98

GL860B

Kruger60B

12.98

GL628

Wolf1061

13.37

GL234A

Ross614A

13.51

GL234B

Ross614B

13.51

GJ1061

L372-58

14.04

GL473A

Wolf424A

14.09

GL473B

Wolf424B

14.09

GL35

VanMaanen's

14.16

NN3522

Gliese3522

14.60

GL83.1

TZAri

14.61

NN3618

Luyten143-23

14.68

GL1

Gliese1

14.75

NN3622

Gliese3622

14.80

GL674

Gliese674

14.89

GL440

Gliese440

14.97

GL832

Gliese832

15.21

GL380

Groombridge1618

15.34

GJ1002

Gleise1002

15.37

GL687

Gliese687

15.38

GJ1245A

Gliese1245A

15.43

GJ1245B

Gliese1245B

15.43

GL682

Gliese682

15.46

GL876

Gliese876

15.48

GL166A

40EridaniA

15.79

GL166B

40EridaniB

15.79

GL166C

40EridaniC

15.79

GL388

ADLeo

16.04

GL768

Altair

16.27

 
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