P Cygni stars
Bp and Ap stars
Herbig Ae/Be stars
VV Cephei
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The characteristic star of this group is P Cygni, a nova which flared up in 1600. P Cygni is now a variable B1 supergiant of 5.0 mean magnitude. P Cygni stars lines shows a profile type called "P Cyg": an emission component to the red side of an aborption line. There are blue super-giant stars. They have larges masses masses and high intrinsic luminosities.
Numerous stars can present some lines with a "P Cyg" profile, but the only true candidate P-Cyg stars are P Cyg itself and AG Car (= Eta Carina) and R 81 (S Dor) in the Large Magellanic Cloud. Other possible members in outer galaxies: SN1961V in NGC 1058 and SN1954J (V12) in NGC 2403.
The spectral profiles can evolve according to the time (these stars are often named LBV for Luminous Blue Variable). P Cygni features is indicative of energetic mass outflows. Some time, LBV shows giant eruptions. For example, Eta Carina became the brightest star in the sky between the years 1837 and 1860! For these events the star ejected at least one solar mass of material. It is estimated that LBV are possible progenitors for Wolf-Rayet stars.
P Cyg localisation:
P Cyg = 34 Cyg R.A.(2000) = 20 h 17 m 47
s Dec.(2000) = +38° 01' 59''
The observations have been made with the middle resolution (R=3000) spectrograph mounted at the focus of 190 mm flat-field telescope and an Audine camera.
The reduction of the numerical spectra from images was achieved with
IRIS softwares. The final treatment of the spectra was performed using
VisualSpec software (spectral responce function
of the detecting system, spectral calibration, radiometric calibration,
normalisation, etc).
Goto P Cyg observations
Bp and Ap stars is a group of B-type or A-type stars where some lines of one or several elements are abnormally enhanced. One can distinguish 3 subgroups:
1. Silicon stars. The enhanced lines are from the Si II at wavelenght
3856 A, 3862 A, 3954 A, 4128 A, 4130 A, 4200 A, 5041 A and 5056 A.
2. HgMn stars. The enhanced lines are from the Mn II at 4206 A and
4136 A and Hg II at 6149 A.
3. Late Ap-type stars. This subgroup contain stars in wich elements
like Sr, Cr and Eu are enhanced (Sr II lines: 4077 and 4215 A, Cr II lines:
4111 A, 4171 A and 4233 A, Eu lines: 3919 A, 3930 A, 4129 A and 4205 A).
Many of this stars exhibit spectral variability (except Mn stars). All the Ap stars have a strong magnetic field, except the manganese stars, where the field is very weak or non-existent. Because the magnetic field, Ap stars are good candidate for Doppler imagery of star surface (spots across the visible disk can produce changes in intensity and shapes of the spectral profiles). For this it is necessary to observe magnetically sensitive lines, like Fe II lines at 4924, 5018 and 6147/49 A for example.
Bright Ap/Bp stars
HD Star R.A. Dec. Spec. Mv
HD 358 alpha And
00 h 08.4 29° 05 B9 HgMn
2.07
HD 1280 theta And
00 h 17.1 38° 41 A2 SiSr
4.62
HD 10221 43 Cas
01 h 42.3 68° 03 A0 SiCr
5.57
HD 11502 gamma Ari
01 h 53.5 19° 18 A1 SiCrSr
4.64
HD 12447
02 h 02.0 02° 46 A2 SiSrCr
4.22
HD 14392 63 And
02 h 21.0 50° 09 B9 Si
5.57
HD 15089 iota Cas
02 h 29.1 67° 24 A4 Sr
4.63
HD 19832 56 Ari
03 h 12.6 27° 15 B8 Si
5.78
HD 32549
05 h 04.6 15° 24 B9 SiCr
4.68
HD 40312A theta Aur
05 h 59.7 37° 13 A0 Si
2.67
HD 51418 nu Aur
05 h 51.5 39° 09 A0 HoDy
3.97
HD 62140 49 Cam
07 h 46.4 62° 50 A8 SrEu
6.47
HD 65339 53 Cam
08 h 01.7 60° 20 A3 SrEuCr
6.02
HD 74521 49 Cnc
08 h 44.7 10° 05 A1 SiEuCr
5.63
HD 89822
10 h 24.1 65° 34 A0 SiHgSr
4.94
HD 112185 epsi Uma
12 h 54.0 55° 57 A1 CrEuMn
1.76
HD 112413 alpha Cvn
12 h 56.0 38° 19 A0 EuSiCr
2.89
HD 118022
13 h 34.1 03° 40 A2 CrEuSr
4.93
HD 129174
14 h 40.7 16° 25 B9 MnHg
4.94
HD 137909A beta CrB
15 h 27.8 29° 06 A9 SrEuCr
3.90
HD 143807
16 h 01.4 29° 51 A0 MnHg
4.98
HD 145389 phi Her
16 h 08.7 44° 56 B9 MnHg
4.22
HD 148112
16 h 25.4 14° 02 A0 CrEu
4.57
HD 152107A
16 h 49.3 45° 59 A3 SrCrEu
4.83
HD 17000A phi Dra
18 h 20.7 71° 20 A0 Si
4.42
HD 176232 10 Aql
18 h 58.8 13° 54 A6 Sr
5.91
HD 183056 4 Cyg
19 h 26.1 36° 19 B9 Si
5.18
HD 201601 gamma Equ
21 h 10.4 10° 07 A9 SrEu
4.70
HD 220825
23 h 26.9 01° 15 A1 CrSrEu
4.94
Herbig Ae/Be stars (so called Herbig-Bell) are young object of spectral type A or earlier, with emission lines, located in an obscured region of the sky and illuminates fairly bright nebulosity in its immediate vicinity (star forming regions). Many of this pre-main sequence stars are located on the Orion nebula. Note that T Tauri type stars are low-mass counterparts of higher-mass Herbig Ae/Be stars. Fu Orionis stars can be also likened to the Herbig Ae/Be class.
Often, the only difference between the Ae/Be stars and the Herbig Ae/Be stars comes from the presence of the association with nebulosity for the last situation. Generaly, the emission concern H-alpha and Ca II H&K lines.
The most bright Herbig-Bell stars:
HD Name R.A. Dec. Mv Spec.
HD 275877 XY Per
3 h 46.6 38° 59 9.36
A5:e
T Tau 4 h 21.9
19° 32 9.90 K0IV, V(Li)
HD 283572
4 h 21.9 28° 18 9.04
G5 IV(Li)
HD 283571 RY Tau
4 h 21.9 28° 27 10.0
KAIV, V(Li)
HD 31293 AB Aur
4 h 55.7 30° 33 7.07
B9, A+e+shl
HD 282624 SU Aur
4 h 56.0 30° 34 8.93
G2 III(Li)
UX Ori 5 h 04.5 -03°
48 9.72 A3e III
RW Aur A 5 h 07.8 30° 24
10.1 K1:
CO Ori 5 h 27.6 11°
26 9.83 F8:e V(Li)
HD 244138 GW Ori
5 h 29.1 11° 52 9.80
G5 (Li)
HD 245059
5 h 34.6 10° 07 9.82
K3 V:(Li)
HD 245185
5 h 35.1 10° 02 9.93
A5e
NV Ori 5 h 35.5 -05°
33 9.91 F4, 8 III,V
MX Ori 5 h 35.6 -05°
09 9.90 G2(Li)
T Ori 5 h 35.8 -05°
29 9.96 A3e
HD36910 CQ Tau
5 h 35.9 24° 44 10.0
A8ve
HD 245465 BN Ori
5 h 36.5 06° 50 9.64
F2,3e
V380 Ori 5 h 36.8 -06° 40
10.0 A1:e
V586 Ori 5 h 37.0 -06° 09
9.54 A2e
FU Ori 5 h 45.6 09°
04 9.24 G; I, II
HD 288313
5 h 54.1 01° 40 9.93
K2:n(Li)
HD 250550 MCW 789 6 h
02.0 16° 31 9.48 B9eq
HD 259431 MCW 147 6 h
33.1 10° 19 8.69 B5:e
HD 53179 Z CMa
7 h 03.7 -11° 33 9.35 B?eq
pec
HD 144668 V856 Sco 16 h 08.6
-39° 06 6.79 A7e III,IV
HD 200775 MCW 361 21 h 01.6
68° 10 7.39 A0pe+shell
HD 152404 AK Sco 16 h
54.7 -36° 53 8.82 F5e
+41°3731 20 h 24.3 42° 18
9.88 B2, 3e
+46° 3471 21 h 52.6 47° 14
10.1 A4:e+shell
VV Cephei (HD208816) is the principal star of a class of massive eclipsing binary consisting of an M supergiant and a hot B type companion. Its optical spectrum is characterized by strong Balmer and [Fe II] emission line. The spectrum is of very complex type: M2Ia-Iabep + B8:Ve (composite spectra, with a very cool star and a hot star together). A mass transfer exist between the two components. For VV Cephei, the orbital period is 7430 days (20.3 years). The date of the mid-point of the last eclipse is January 4, 1998. At the time of eclipse the H-alpha emission disappear progressively. The total duration of the eclipse is about 1100 - 1400 days. VV Cep is also a semi-regular long-period variable (magnitude = 4.8 - 5.4). For more info, click here. Other members of VV Cep class: KN Cas, AZ Cas, KP Pup, W Cep, U Lac, Alpha Sco.
VV Cep localisation:
VV Cep = HD 208816 R.A.(2000) = 21 h 56
m 39s Dec.(2000) = 63° 37' 32"
Go to VV Cep observations
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