Variable Vista - January 2008
A monthly look at what is happening in the world of variable star observing.
Cepheid
Predicted date of maximum brightness.
Eta Aql - 5th - 12th - 19th - 26th
FF Aql - 4th - 9th - 13th - 18th - 22nd - 27th
TT Aql - 4th - 18th - 31st
U Aql - 1st - 8th - 15th - 22nd - 29th
RX Aur - 10th - 22nd
48 Aur - 3rd - 7th - 11th - 15th - 18th - 22nd - 26th - 29th
DL Cas - 3rd - 11th - 19th - 27th
RW Cas - 1st - 16th - 31st
Delta Cep - 5th - 11th - 16th - 21st - 27th
W Gem - 8th - 16th - 24th
zeta Gem - 8th - 18th - 29th
AW Per - 6th - 12th - 19th - 25th
SZ Tau - 1st - 4th - 8th - 11th - 14th - 17th - 20th - 23rd - 26th - 30th
SV Vul - 9th
Eclipsing Binary
EA Types
Predicted date and time (in UT) for mid-eclipse.
RZ Cas - 1st 06:00 - 4th 20:00 - 6th 01:00 - 7th 06:00 - 10th 20:00 - 12th 01:00 - 13th 05:00 - 17th 23:00 - 19th 05:00 - 22nd 19:00 - 23rd 23:00 - 25th 04:00 - 28th 18:00 - 29th 23:00 - 31st 03:00
U Cep - 6th 01:00 - 11th 01:00 - 16th 01:00 - 20th 23:00 - 25th 23:00 - 30th 23:00
Beta Per - 10th 06:00 - 13th 03:00 - 15th 23:00 - 18th 21:00
EB Types
Predicted date of minimum.
Beta Lyrae - 11th - 24th
Long Period Variables
Predicted dates of maxima for this months bright LPV stars.
Expected magnitude given in brackets.
| RT CVn 1st (9.9) | R Leo 1st (5.8) | S Cyg 3rd (10.3) | Y Cas 3rd (10.0) |
| R CMi 9th (8.5) | X Oph 10th (6.8) | V CMi 12th (9.0) | RT Cyg 12th (7.5) |
| R Vul 13th (8.5) | T Gem 15th (9.0) | X And 19th (9.2) | R Lac 19th (9.3) |
| V Cyg 22nd (9.1) | Z Oph 24th (8.5) | S Boo 26th (8.7) | S Ori 26th (8.5) |
| R Aur 31st (8.0) |
At the Eyepiece - FU Orionis
Detected on photographic plates by A.A.Wachmann in 1939, this tenth magnitude object was at first thought to be a Nova, and was given the designation Nova Ori 1939. Its previous magnitude had been a faint mag.16.0. Earlier photographic plates, revealed that the star had been bright for two years with maximum brightness being reached in the summer of 1937 at mag.9.6, leading many at the time to suggest that this was the slowest nova ever detected.
FU Orionis
Today, FU Ori still remains bright, and is the prototype of the class FU Orionis stars (FUORS). The FU Orionis stars are not nova, but rather T -Tauri type pre-main sequence stars. These are stars that have yet to obtain a high enough central core temperature to ignite nuclear reactions. Instead, the stars obtain their energy by gravitational energy release from instabilities within an accretion disk.
Many Fu Ori stars remain faint, but sudden flares and outbursts of up to 6 magnitudes can make them visible in amateur telescopes and binoculars. After outburst, the star can remain bright for extremely long periods of time (years to decades), while declining very slowly by 1-2 magnitudes. The FU Ori stars tend to be associated with nebulosity. Indeed, FU Ori is located at the apex of a fan-shaped nebula within the dark cloud Barnard 35.
Recent Events
T Cephei
Easily seen in binoculars at magnitude 5.8.
Omicron Ceti
Now visible with the naked-eye. Maximum is predicted for the first week in February 2008.
R Coronae Borealis
Deep fade continues, at mag.13.8
Gamma Cassiopeiae
Slight brightening at mag.2.1
Chi Cygni
Fade continues. Now below magnitude 9.0
R Gem
Maximum reached during December at 7.2.
Beta Leonis
Constant at 2.1
R Leonis
Reached maximum brightness a couple of weeks before predicted date. Bright at mag.5.8 during first week of December.
Alpha Orionis
Appears to be fading in its cycle.
U Orionis
Continues to increase in brightness. Observed at mag.9.9/10.0.
R Serpentis
Fading (mag.7.7).
R Trianguli
Seen at mag.11.2
Delta Ursae Majoris
Constant at mag.3.5
R Ursae Majoris
Rapid decrease during December, fading to below magnitude 11.3.
S Ursae Majoris
Now an elventh magnitude object.
T Ursae Majoris
Decrease by one and a half magnitudes. Now observed at mag.12.5.
