The Pleiades M45: Stars and nebulae (original) (raw)
M45 with star names labelled in the photograph, taken by David Malin with the UK Schmidt Telescope. Courtesy Anglo-Australian Observatory / Royal Observatory Edinburgh.
A table of the brightest Pleiades member stars follows. Also noteSteven Gibson's Brightest Pleiads table.
Star Name RA (2000.0) Dec (2000.0) mag Spectrum Nebulosity
16 Celaeno 03:44:48.22 +24:17:22.1 5.44 B7 IV Ced 19c
17 Electra 03:44:52.54 +24:06:48.0 3.70 B6e III vdB 20
18 HD 23324 03:45:09.74 +24:50:21.3 5.65 B8 V
19 Taygeta 03:45:12.49 +24:28:02.2 4.29 B6 V Ced 19e
20 Maia 03:45:49.61 +24:22:03.9 3.86 B7 III NGC 1432 (vdB 21)
21 Asterope 1 03:45:54.48 +24:33:16.2 5.64 B8e V Ced 19h
22 Asterope 2 03:46:02.90 +24:31:40.4 6.41 B9/A0 Vn Ced 19h
23 [Merope](m045%5Fmerope.html) 03:46:19.57 +23:56:54.1 4.17 B6 IV NGC 1435 (VdB 22) + [IC 349](m045%5Fi349.html) (Ced 19i)
24 HD 23629 03:47:21.04 +24:06:58.6 6.28 A0 V Eta 25 Alcyone 03:47:29.08 +24:06:18.5 2.86 B7e III vdB 23
HD 23753 03:48:20.82 +23:25:16.5 5.44 B8 V
26 HD 23822 03:48:56.94 +23:51:25.7 6.48 F0 [Non-member foreground star]
27 Atlas 03:49:09.74 +24:03:12.3 3.62 B8 III Ced 19o
BU 28 Pleione 03:49:11.22 +24:08:12.2 5.09v B8e p Ced 19p
HD 23923 03:49:43.53 +23:42:42.7 6.17 B8 V
HD 23950 03:49:55.07 +22:14:38.9 6.07 B8 III
Key:
Star
Star letter or number; "eta" is "eta Tauri", "27" is "27 Tauri", etc.
Name
Common name of the star
mag
Apparent visual magnitude
Sp
Spectral type of star
Nebulosity
Catalog number of associated nebulosity (if one is present)
A list of the brightest Pleiades, ordered by visual brightness, follows; from this list the number of visible stars for given limiting magnitudes can be estimated:
Star Name m_vis
Eta = 25 Alcyone 2.86 27 Atlas 3.62 17 Electra 3.70 20 Maia 3.86 23 Merope 4.17 19 Taygeta 4.29 BU = 28 Pleione 5.09v 21+22 Asterope 5.31 (combined) 16 Celaeno 5.44 HD 23753 5.44 21 Asterope 1 5.64 18 HD 23324 5.65 HD 23950 6.07 HD 23923 6.17 24 HD 23629 6.28 22 Asterope 2 6.41 26 HD 23822 6.48 [Non-member]
The most conspicuous of the Pleiades reflection nebulae is NGC 1435 around Merope, also called "Tempel's Nebula". This is the only one which was known to John Herschel when he compiled his General Catalog (GC) in 1864, and has been assigned the number GC 768. It has a faint extension, IC 349, which is very small and 36" south following (east) of Merope.
The star Maia (20 Tauri) was subject to speculation when Otto Struve brought up the hypothesis that it might be the representative of a new type of variables of spectral type B7-A3 near-main sequence stars, of some ours period and small amplitudes. However, various photometric investigations have proven that Maia (and other suspected "Maia Variables" such as Gamma UMa) is of constant brightness.
In the region of the sky around the Pleiades, a number of more diffuse nebulae can be found, many of them discovered by Barnard (1894) who referred to them as the "exterior nebulosities of the Pleiades." The following table lists the NGC and IC nebulae (and suspected nebulae) in the wider field around the Pleiades:
Nebula RA (2000.0) Dec Type Cross References, Discoverer
IC 1941 03:32.2 +24:26 3St D.S. 202 IC 336 03:38.2 +23:28 Neb Barnard (AN 3253) IC 341 03:41.2 +21:57 Neb Barnard (AN 3253) NGC 1432 P 03:45.8 +24:22 Neb Maia Neb, in M45; Henry NGC 1435 P 03:46.1 +23:47 Neb in M45; Tempel (1859 Oct 19), Tempel's Neb, Merope Neb, GC 768 IC 349 P 03:46.3 +23:56 Neb in M45; Barnard's Merope N, Barnard (AN 3018) M 45 P 03:47.0 +24:07 OC Pleiades IC 1990 03:47.5 +24:37 Neb Stratonoff (AN 3366) NGC 1456 03:48.2 +22:34 DSt J G Lohse IC 1995 03:50.3 +25:35 Neb Barnard IC 354 03:53.3 +23:25 Neb Barnard (AN 3253) IC 353 03:55.0 +25:29 Neb Barnard (AN 3253) IC 360 04:13.0 +25:38 Neb Barnard (AN 3253)
A "P" is marking objects situated within the boundaries of the Pleiades cluster. "Type": "Neb," Nebula; "OC," Open Cluster; "DSt," Double Star; "3St," Three Stars.
The present author has no information if any of these nebulae is associated with the Pleiades or their nebulosity. The diffuse nebulae IC 353, IC 354 and IC 360 are about 1 degree north following of the Pleiades. Region from the Pleiades to these nebulae. North of the boundary of the Pleiades lies the diffuse nebula IC 1990, found by Stratonoff, an emission nebula. It surrounds the double star ADS 2799 (A: 5.9 m, B: 6.3 m, separation 0.4"), see e.g. Vehrenberg's Atlas of Deep Sky Splendors.