russw2007
Sigma Orionis (Struve 762) 1X
Multiple Star Sigma Orionis (Struve 762) is at the center of the image. Components A and B are too close for this imaging system to resolve. At magnitude 8.79, component C is too faint to be seen in this short exposure image. However, C's general position is labeled. Component D is just noticeable protruding from A, but is not fully resolved. Component E, just to the left (east) of A, is clearly split at this scale. E is also a variable star (V1030 Ori). [1,2]
Sigma Orionis (AB), the primary star of the system, is visible to the naked eye even from some light polluted downtown Oklahoma City locations. It lies just below (southwest) of Alnitak, the lowest (southernmost) star of Orion's belt. Visually, components AB, C, D and E should all be split easily at about 100-200X with a small (150mm) telescope.
The Washington Double Star Catalog shows the separation between stars AB and E as 41.2 arc seconds. [3] It lists AB as magnitude 3.73 and E as magnitude 6.34.
Struve 761, another multiple star system, is visible toward the upper right (northwest) of Sigma Orionis. The southernmost member of 761 is a binary system that is not quite resolved into separate components in this image.
Both of these multiple star systems are part of the Sigma Orionis Cluster. The Sigma Orionis Cluster is between 350 and 500 light years away and is composed of very young stars in the age range of two to three million years old. [4]
Washington Double Star Catalog Data
Sigma Orionis (Struve 762)
AB,C Separation: 10.9 arc seconds
AB, C Position Angle: 238 degrees
AB, C Magnitude: 3.73, 8.79
Epoch: 2006
AB, D Separation: 12.5 arc seconds
AB, D Position Angle: 84 degrees
AB, D Magnitude: 3.73, 6.56
Epoch: 2007
AB, E Separation: 41.2 arc seconds
AB, E Position Angle: 61degrees
AB, E Magnitude: 3.73, 6.34
Epoch: 2007
Image Details
Orientation is only approximate (north up, east left).
Date: January 19, 2009 03:16:42 UT
Telescope: Meade LXD75 203mm f/4 Schmidt-Newtonian
Camera: Meade DSI1
Image: Stack of 6 images at 2 seconds each. LRGB combined in AIP4WIN. Processed in AIP4WIN and Photoshop.
ID: SigOri3aLRGBRot011909BLbl
References
1. Groote, D., Hunger, K., 1982, Shell and Photosphere of Sigma Ori E: New Observations and Improved Model, Astronomy & Astrophysics, 116, 64-74, articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?19...
2. American Association of Variable Star Observers (AAVSO), The International Variable Star Index (VSX), www.aavso.org/vsx/index.php?view=detail.top&oid=24093 (last accessed January 21, 2009).
3. Mason, B.D., Wycoff, G.L., Hartkopf, W.I., The Washington Double Star Catalog, U.S. Naval Observatory, Washington, D.C., ad.usno.navy.mil/wds (last accessed January 19, 2009).
4. Sherry, W.H., Walter, F.M., Wolk, S.J., Adams, N.R., 2008, Main sequence fitting to the Sigma Orionis Cluster, Astronomical Journal, 135, 1616-1623,
arxiv.org/abs/0801.2585 (e-print).
Sigma Orionis (Struve 762) 1X
Multiple Star Sigma Orionis (Struve 762) is at the center of the image. Components A and B are too close for this imaging system to resolve. At magnitude 8.79, component C is too faint to be seen in this short exposure image. However, C's general position is labeled. Component D is just noticeable protruding from A, but is not fully resolved. Component E, just to the left (east) of A, is clearly split at this scale. E is also a variable star (V1030 Ori). [1,2]
Sigma Orionis (AB), the primary star of the system, is visible to the naked eye even from some light polluted downtown Oklahoma City locations. It lies just below (southwest) of Alnitak, the lowest (southernmost) star of Orion's belt. Visually, components AB, C, D and E should all be split easily at about 100-200X with a small (150mm) telescope.
The Washington Double Star Catalog shows the separation between stars AB and E as 41.2 arc seconds. [3] It lists AB as magnitude 3.73 and E as magnitude 6.34.
Struve 761, another multiple star system, is visible toward the upper right (northwest) of Sigma Orionis. The southernmost member of 761 is a binary system that is not quite resolved into separate components in this image.
Both of these multiple star systems are part of the Sigma Orionis Cluster. The Sigma Orionis Cluster is between 350 and 500 light years away and is composed of very young stars in the age range of two to three million years old. [4]
Washington Double Star Catalog Data
Sigma Orionis (Struve 762)
AB,C Separation: 10.9 arc seconds
AB, C Position Angle: 238 degrees
AB, C Magnitude: 3.73, 8.79
Epoch: 2006
AB, D Separation: 12.5 arc seconds
AB, D Position Angle: 84 degrees
AB, D Magnitude: 3.73, 6.56
Epoch: 2007
AB, E Separation: 41.2 arc seconds
AB, E Position Angle: 61degrees
AB, E Magnitude: 3.73, 6.34
Epoch: 2007
Image Details
Orientation is only approximate (north up, east left).
Date: January 19, 2009 03:16:42 UT
Telescope: Meade LXD75 203mm f/4 Schmidt-Newtonian
Camera: Meade DSI1
Image: Stack of 6 images at 2 seconds each. LRGB combined in AIP4WIN. Processed in AIP4WIN and Photoshop.
ID: SigOri3aLRGBRot011909BLbl
References
1. Groote, D., Hunger, K., 1982, Shell and Photosphere of Sigma Ori E: New Observations and Improved Model, Astronomy & Astrophysics, 116, 64-74, articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?19...
2. American Association of Variable Star Observers (AAVSO), The International Variable Star Index (VSX), www.aavso.org/vsx/index.php?view=detail.top&oid=24093 (last accessed January 21, 2009).
3. Mason, B.D., Wycoff, G.L., Hartkopf, W.I., The Washington Double Star Catalog, U.S. Naval Observatory, Washington, D.C., ad.usno.navy.mil/wds (last accessed January 19, 2009).
4. Sherry, W.H., Walter, F.M., Wolk, S.J., Adams, N.R., 2008, Main sequence fitting to the Sigma Orionis Cluster, Astronomical Journal, 135, 1616-1623,
arxiv.org/abs/0801.2585 (e-print).