New Forest Observatory ®

UU Aurigae

Star name:                                           UU Aurigae

Other names:

Constellation:                                      Auriga

Other ID:                                             SAO 59280, HD 46687, HIP 31579, HR 2405, BD+38 1539

Magnitude:                                          5.446

Absolute magnitude:                            -3.1 +/- 1.1

Luminosity, Sun = 1:                           1400 +/- 1400

R.A. 2000:                                          06hr 36min 32.8364sec

Dec 2000:                                           +38deg 26min 43.8sec

Spectral type:                                      C5II semiregular variable

Temperature:                                       3,450 K

Mass, solar masses:

Radius, solar radii:

Distance in light-years:                       1,630 +/- 820

UU Aurigae is a binary Carbon star in the constellation Auriga.  Period of variation 441 days.

RS Cygni

Star name:                                           RS Cygni

Other names:

Constellation:                                      Cygnus

Other ID:                                             SAO 69636, HIP 99653, PPM 84477, HD 192443, B+38 3957

Magnitude:                                          7.1 to 8.5

Absolute magnitude:                            -0.77
+/- 0.92

Luminosity, Sun = 1:                           170 +/- 140

R.A. 2000:                                          20hr 13min 23.662sec

Dec 2000:                                           38deg 43min 44.47sec

Spectral type:                                      C5II

Temperature:

Mass, solar masses:

Radius, solar radii:

Distance in light-years:                       1550 +/- 650

This Carbon star lies very close to the Crescent nebula (NGC6888, an emission nebula formed from the Wolf-Rayet star HD 192163) in the constellation Cygnus.  The mean period of the variability of RS Cygni is 434.1 days.

La Superba

Star name:                                          La Superba

Other names:                                      Y Canum Venaticorum

Constellation:                                     Canes Venatici

Other ID:                                             SAO 44317, HIP 62223, HD110914, HR4846, GC17342

Magnitude:                                         4.8 to 6.3 (variable over 160 days)

Absolute magnitude:                          -7.63

Luminosity, Sun = 1:                          4,400

R.A. 2000:                                          12hr 45min 07.827sec

Dec 2000:                                           +45deg 26min 24.922sec

Spectral type:                                     C7 (CN5) supergiant

Temperature:                                      2,200 (2,800) K

Mass, solar masses:                            3

Radius, solar radii:                             215

Distance in light-years:                      711 +/- 113

La Superba in the constellation Canes Venaticorum is one of the brightest Carbon stars in the sky but it is not a naked-eye object as most of its output is in the infrared part of the spectrum.  It was named “La Superba” by Father Angelo Secchi who was amazed at the beauty of its spectrum, and as you can see in the accompanying (north up) image, it is a strikingly brilliant red star.  La Superba is a very special type of Carbon star, it is in fact the brightest “J-star” in the sky, where a J-star is a very rare group of Carbon stars that has an abundance of Carbon-13 (heavy Carbon).  At between 2,200 and 2,800 K La Superba is one of the coolest true stars known.  In the accompanying image, which was the Astronomy Picture of the Day (APOD) for December 18th 2008, we once again see the obligatory brilliant blue star (SAO 44292) lying at the 1 O’clock position from La Superba.  There are also a number of faint background galaxies in this image, the most obvious lying at the 7 O’clock position which is magnitude 15.7 PGC 43044.

119 Tauri/CE Tauri

Star name:                                          CE Tauri

Constellation:                                     Taurus

Other ID:                                             119 Tauri, SAO 94628, HIP25945, HD36389, B+18 875, HR1845, GC 6841

Magnitude:                                         4.32

Absolute magnitude:                          -4.38+/-0.31

Luminosity, Sun = 1:                          44,000 (variable)

R.A. 2000:                                          05hr 32min 56.552sec

Dec 2000:                                           +18deg 35min 39.243sec

Spectral type:                                     M2Ib

Temperature:                                      3,500K (variable)

Mass, solar masses:                            14

Radius, solar radii:                             608 (variable)

Distance in light-years:                      1918.57

This is the second reddest star in the entire night sky after Mu Cephei (the Garnet Star in Cepheus right next to the huge emission nebula IC1396).  CE Tauri is an M-type pulsating red supergiant (semiregular variable) first recognised by A. Ahad as the second reddest star in the sky.  In the accompanying image (north up) we note a nice blue star just to the left of CE Tauri, this is SAO 94649 (120 Tauri), and it is surprising just how many bright red stars seem to have a bright blue close-by companion.  This semiregular variable changes magnitude by approximately 0.3 over a period of around 165 days.  CE Tauri is metal-rich and is likely to be fusing its Helium into Carbon, although Carbon fusion itself cannot be ruled out.  As 119 Tauri is only 4.6 degrees off the ecliptic it affords accurate measurements of its size by lunar occultation measurements.  Look at the Luminosity and Radius of this star – it is a giant in every way.