The First Known Variable Stars

Although there were occasional reports of new or guest stars in all cultures through the ages, medeval western astronomers looked at the "fixed" stars as eternal and invariable entities. This view was blown up in a dramatic show by Tycho's supernova ("Stella Nova", "New Star") in 1572. Soon after, some more variable stars were discovered, including the first periodic one, Mira (the periodicity of which was only discovered considerably later in 1638, by Holwarda; up to this time the four known variables had all been classified as "Stellae Novae", although none of them was actually a nova). However, the discovery rate of variables continued to stay on low level. In 1715, Edmond Halley published a list containing all 6 variables known at that time, and in 1781-2, when William Herschel discovered Uranus and published a catalog of 269 double stars, and Charles Messier published his catalog of 103 nebulae and star clusters, still only 8 variables were known, 4 of them periodic, all of Mira type (we have to discount the Cas A supernova in this counting because it had not been realized as variable or nova by that time).

The research of variables became a more serious science not before 1844, when F.W. Argelander called for their observation, and published a list of those variables then known (basically what we have in our table below).

According to G.D. Roth, the number of known variable stars has developed as follows: 12 by 1786, 18 by 1844, 175 by 1890, 393 by 1896, 4,000 by 1912, 22,650 by 1970, and 28,450 by 1983. As Hoffmeister states, of the 18 variables "known" in 1844, a list which had been published by F.W. Argelander, two (Alpha Cassiopeiae and Alpha Hydrae) are actually not variable, while Argelander had missed R Cancri (also). The most reliable reference, however, is probably Isles, who has researched at least one variable (Epsilon Aurigae) which had been neglected by the other references (he also lists i Bootis B, but this was probably erroneus, confusing the discovery of the double with that of its variability).

Here is an attempt to list the earliest known variables (based on Isles, Hoffmeister and Strohmeier; note that Roth's numbers can apparently not be verified from this list); we hope to be rather complete for the time before 1844. We want to give basic data, images (where available) and links for each of these variable stars.

Early Variable Star Discoverers

List of all images

Name                        Con  Type       Year Discoverer
                       
SN 1054, CM Tau (M1, Crab)  Tau  SN         1054 [Chinese, Native American, Japanese]
SN 1572                     Cas  SN         1572 W. Schuler, Tycho Brahe
Mira, Omicron Ceti          Cet  Mira       1596 David Fabricius
P Cygni, Nova 1600 Cygni    Cyg  S Dor      1600 Willem Janszoom Blaeu
SN 1604                     Oph  SN         1604 Brunowsky, Joh. Kepler
Algol, Beta Persei          Per  Algol      1669 Geminiano Montanari
Nova Vulpeculae 1670, CK    Vul  Nova       1670 Dom Anthelme
SN 1680 ? 1667 ? (Cas A)    Cas  SN         1680 John Flamsteed ? 1667 ?
Chi Cygni                   Cyg  Mira       1687 Gottfried Kirch
R Hydrae                    Hya  Mira       1704 Giacomo Filippo Maraldi
R Leonis                    Leo  Mira       1782 J.A. Koch
Nova 1783 Sagittae, WY Sge  Sge  Nova       1783 D'Agelet
Eta Aquilae                 Aql  Delta Cep  1784 Edward Pigott
Sheliak, Beta Lyrae         Lyr  Beta Lyr   1784 John Goodricke
Delta Cephei                Cep  Delta Cep  1784 John Goodricke
Ras Algheti, Alpha Herculis Her  SR c       1795 William Herschel
R Coronae Borealis          CrB  R CrB      1795 Edward Pigott
R Scuti                     Sct  RV Tau a   1795 Edward Pigott
R Virginis                  Vir  Mira       1809 Harding
R Aquarii                   Aqr  Mira       1810 Harding
Epsilon Aurigae             Aur  Algol      1821 Fritsch
R Serpentis                 Ser  Mira       1826 Harding
Eta Carinae                 Car  S Dor      1827 Burchell, discovered 1677 Edmond Halley
S Serpentis                 Ser  Mira       1828 Harding
R Cancri                    Cnc  Mira       1829 Schwerd
Betelgeuse, Alpha Orionis   Ori  SR c       1836 John Herschel

Note: The supernovae of 1572 and 1604 were almost simultaneously noted by various observers. While Strohmeier lists Eta Carinae as being discovered, as variable, by Halley in 1677, Isles credits this discovery to Burchell, 1827. Isles reports that Goodricke and Pigott were amateur astronomers and neighbors, working together in the field of variable star research; Goodricke died from pneumonia he caught probably when observing Delta Cephei in 1786.

Of the 26 variables listed here, 17 are showing periodic (or quasi-periodic) variability (3 eclipsing and 14 pulsating variables), while 9 are of eruptive type. The stars are representatives of the following types:

3 eclipsing variables: 2 EA (Algol), 1 EB (Beta Lyr)
14 pulsating variables: 2 Delta Cephei stars, 9 miras, 1 RV Tauri star, 2 semiregular variables
9 eruptive variables: 4 supernovae, 2 novae, 2 S Dor stars, 1 R Coronae Borealis star (R CrB)

Astronomical data of these variables

Most of the data are from the Brightest Stars in the Sky collection at the MAA, supplemented by data from the Sky Catalogue 2000.0.

Name                Con  RA (2000)  Dec(2000)  Type  max  min   Period    Spectr
                                                                     
SN 1054     CM      Tau  05:34:31.9 +22:00:52  SN   -6    17.7            cont
SN 1572     B       Cas  00:25.3    +64:08.3   SN   -4   >19.0         A8/9V
Mira        Omicron Cet  02:19:20.7 -02:58:39  Mira  2.0  10.1   331.96   M7IIIe
            P       Cyg  20:17:47.1 +38:01:59  SDor  3.0   6.0            B2pe
SN 1604     V 843   Oph  17:30:37.2 -21:28:51  SN   -3   >19.0
SN 1680?67? 3       Cas  23:23.4    +58:50     SN    6?        
Algol       Beta    Per  03:08:10.1 +40:57:21  EA    2.12  3.40    2.867  B8V+G5IV+Am
Nova 1670   CK      Vul  19:47.6    +27:19     Nova  2.7       
            Chi     Cyg  19:50:33.8 +32:54:51  Mira  3.3  14.2   406.93   S6.2-10.4e
            R       Hya  13:29:42.7 -23:16:52  Mira  3    11     389.61   M7IIIe
            R       Leo  09:47:33.4 +11:25:43  Mira  4.4  11.3   312.43   M8IIIe
Nova 1783   WY      Sge  19:32.7    +17:45     Nova  5.4  19.5           
            Eta     Aql  19:52:28.3 +01:00:20  DCep  3.48  4.39    7.177  F6Ibv
Sheliak     Beta    Lyr  18:50:04.7 +33:21:46  EB    3.34  4.34   12.936  B7Ve+A8p
            Delta   Cep  22:29:10.2 +58:24:55  DCep  3.48  4.37    5.366  F5Ib-G2Ib
Ras Algethi Alpha   Her  17:14:38.8 +14:23:25  SR c  3.1   3.9    mult    M5Ib-II
            R       CrB  15:48:34.3 +28:09:24  RCrB  5.85 14.8            G0Iep
            R       Sct  18:47:28.9 -05:42:18  RV a  4.45  8.20  140.05   K0Ibpv
            R       Vir  12:38:29.9 +06:59:18  Mira  6.0  12.1   145.64   M4.5IIIe
            R       Aqr  23:43:49.4 -15:17:04  Mira  5.8  12.4   386.96   M7IIIpev
            Epsilon Aur  05:02.0    +43:49     EA    2.92  3.83 9892      A8Ie-F2Iaep
            R       Ser  15:50:41.6 +15:08:00  Mira  5.16 14.4   356.41   M7IIIe
            Eta     Car  10:45:03.6 -59:41:03  SDor -0.8   7.9            Pec
            S       Ser  15:21.7    +14:19     Mira  7.0  14.1   368.59   M5-6e
            R       Cnc  08:16:33.9 +11:43:35  Mira  6.07 11.8   361.60   M7IIIe
Betelgeuse  Alpha   Ori  05:55:10.3 +07:24:25  SR c  0.40  1.3 ~2070:     M1-2Ia-Iab

Key:

Name: Common name and/or Bayer or variable star designation
Con: Constellation
RA (2000), Dec (2000): Right Ascension and Declination for epoch 2000.0
Type: Variable star type: Cataclysmic: SN = supernova, Nova, SDor/S Dor = S Doradus (Hubble-Sandage Variables); Pulsating: Mira, DCep/Delta Cep = Delta Cephei variables, SR c = semi-regular supergiants, RV a = RV Tauri stars; Eclipsing binaries: EA/Algol = Algol type (separated), EB/Beta Lyrae = Beta Lyrae type (half separated), Other: RCrB/R CrB = Irregular variable, carbon stars
max, min: Maximum and minimum visual brightness in magnitudes; extreme values given.
Period: Period of variation in days
Spectr: Spectral type

References

A. Hirshfeld and R.W. Sinnott, Sky Catalogue 2000.0, Vol. 2: Double Stars, Variable Stars and Non-Stellar Objects. 1985, Cambridge University Press and Sky Publishing Corporation, ISBN 0-521-27721-3. Section on variable stars is p. 222-260.
C. Hoffmeister, G. Richer and W. Wenzel, Veränderliche Sterne. Second revised edition 1984, J.A. Barth, Leipzig and Springer, ISBN 3-540-13396-8 (English translation: ISBN 0-387-13396-8)
Helen Sawyer Hogg, Variable Stars. Ch. 5 in Astrophysics and twenties-century astronomy to 1950: Part A, by Owen Gingerich (ed.), Vol. 4A of The General History of Astronomy series, p. 73-89, 1984, Cambridge UP, ISBN 0-521-24256-8.
John E. Isles, Webb Society Deep-Sky Observer's Handbook, Volume 8: Variable Stars; series edited by Kenneth Glyn Jones. 1990, Enslow Publishers, Hillside (NJ), ISBN 0-89490-208-3
G.D. Roth, An Historical Exploration of Modern Astronomy. Ch. 11 in Compendium of Practical Astronomy, by G.D. Roth (ed.), revised translation of Handbuch für Sternfreunde, 4th edition, p. 425-435, 1994, Spinger Verlag, ISBN 0-387-53596-9
W. Strohmeier, Variable Stars. 1972, Pergamon Press, Oxford.

The First Known Variable Stars

Astronomical data of these variables

References

Links