The Solar Neighbourhood

Within 25 parsecs of the Sun, the number of known stars has risen to almost 3000 but it is still not clear how many more there are to find. Recent estimates indicate that we have only found about half of the stars within this volume of space. The reason for this is that the remaining stars are very faint, but continually improving methods and instrumentation will continue to uncover new neighbours to the Sun in the next few years.

The data in Tables 6.1 and 6.2 is slightly adapted from the Catalogue of Nearby Stars courtesy of Dr H. Jahreiss and the Astronomische-Rechen Institut, Heidelberg (June 2002).

The proportion of binary stars in this population can be seen in Table 6.3 where the totals given are accumulating values. Within 5 parsecs half of the stars are in binary systems and another 5% are in triples. However this volume of space represents less than 1% of the volume within 25 parsecs. The average number of stars decreases from 0.118 per cubic parsec within 5 pc to 0.039 per cubic parsec from 20 to 25 pc.

Planetary companions are listed in the penultimate column and at the time of writing the nearest extrasolar planet to the Sun orbits the M dwarf star Gl 876 some 4.6 parsec distant.

Table 6.1. Double and multiple stars within 5 parsecs of the Sun.

CNS

Comp.

RA 2000 Dec

Spectrum

(l. y.)

Luminosity Sun = 1)

Sun

G2 V

-26.75

0.65

1.0

Gl 551

14 29 43 -62 40.8

M5.5

11.04

1.81

4.24

0.00006

Gl 559

A

14 39 36 -60 50.1

G2V

0.01

0.71

4.37

1.50

Gl 559

B

14 39 36 -60 50.1

K0V

1.35

0.90

4.37

0.44

Gl 411

11 03 21 +35 58.2

M2V

7.49

1.51

8.31

0.0056

Gl 244

A

06 45 09 -16 43.0

A1V

-1.44

0.00

8.60

22.2

Gl 244

B

06 45 09 -16 43.0

DA2

8.44

-0.03

8.60

0.0025

Gl 65

A

01 39 01 -17 57.0

M5.5V

12.55

1.87

8.73

0.00006

Gl 65

B

01 39 01 -17 57.0

M6V

13.00

8.73

0.00004

Gl 144

03 32 55 -09 27.5

K2V

3.72

0.88

10.50

0.28

Gl 866

A

22 38 33 -15 18.1

M5V

12.87

1.99

11.27

0.00007

Gl 866

B

22 38 33 -15 18.1

13.27

11.27

0.00005

Gl 280

A

07 39 18 +05 13.5

F5IV-V

0.35

0.42

11.41

7.5

Gl 280

B

07 39 18 +05 13.5

DA

10.75

11.41

0.0005

Gl 820

A

21 06 55 +38 44.8

K5V

5.22

1.17

11.41

0.085

Gl 820

B

21 06 55 +38 44.8

K7V

6.04

1.36

11.41

0.040

Gl 725

A

18 42 45 +59 37.9

M3V

8.90

1.53

11.60

0.003

Gl 725

B

18 42 46 +59 37.6

M3.5V

9.69

1.59

11.60

0.0014

Gl 15

A

00 18 23 +44 01.4

M1.5V

8.08

1.56

11.64

0.006

Gl 15

B

00 18 26 +44 01.7

M3.5V

11.05

1.81

11.64

0.0004

Gl 860

A

22 28 00 +57 41.8

M3V

9.79

1.65

13.18

0.002

Gl 860

B

22 28 00 +57 41.8

M4V

11.46

1.8

13.18

0.0004

Gl 234

A

06 29 24 -02 48.8

M4.0V

11.15

1.72

13.43

0.00050

Gl 234

B

06 29 24 -02 48.8

M5.5V

14.24

13.43

0.00003

Gl 473

A

12 33 17 +09 01.3

M5.5V

13.20

1.85

14.31

0.00009

Gl 473

B

12 33 17 +09 01.3

M7

13.19

14.31

0.00009

Gl 687

AB

17 36 25 +68 20.3

M3V

9.16

1.49

14.77

0.004

GJ 1245

A

19 53 54 +44 24.9

M5.5V

13.47

1.92

14.81

0.00007

GJ 1245

B

19 53 55 +44 24.9

M6V

14.01

1.97

14.81

0.00004

GJ 1245

C

19 53 54 +44 24.9

16.78

14.81

0.000003

Gl 876

22 53 17 -14 15.8

M3.5V

10.16

1.58

15.33

0.0016

Gl 412

A

11 05 29 +43 31.6

M1V

8.76

1.55

15.76

0.006

Gl 412

B

11 05 31 +43 31.3

M5.5V

14.41

2.00

15.76

0.00003

Gl 388

10 19 36 +19 52.2

M3V

9.40

1.54

15.94

0.004

Gl 166

A

04 15 16 -07 39.2

K1Ve

4.42

0.82

16.45

0.37

Gl 166

B

04 15 22 -07 39.5

A4

9.51

0.04

16.45

0.0034

Gl 166

C

04 15 22 -07 39.5

M4.5V

11.20

1.65

16.45

0.0007

Gl 702

A

18 05 28 +02 30.0

K0Ve

4.21

0.78

16.59

0.45

Gl 702

B

18 05 28 +02 30.0

K5Ve

6.01

16.59

0.086

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