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Gamma (γ) Delphini
Optical Double Star
| Right Ascension | 20h 46m 38.9s | Best Seen | 8/1 - 12/15 |
| Declination | 16° 07' 27" | Combined Magnitude | 4.01 |
| Apparent Separation | 42" | Constellation | Delphinus |
Actual |
Compared to Sun |
|
| Distance | 103 / 101 ly | -- |
| Separation | 36.8 billion miles | 396 au |
| Orbital Period | 3,249 yrs | -- |
| Actual Brightness | -- | 6.2 / 13 |
| Magnitude | 5.25 / 4.44 | -- |
| Mass | -- | -- |
| Surface Gravity | -- | -- |
| Surface Composition (by mass) | 74% hydrogen 24% helium 2% everything else |
same |
| Spectral Type | K1 IV / A2 Ia | G2 V |
| Density (gram/cubic cm) | -- | -- |
What To Look For Through The Telescope
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Recommended eyepiece: 24mm or 40 mm.
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When people look through the telescope they should see two stars next to each other. One of the stars should be slightly brighter than the other.
Gamma Delphini Informatino:
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This is a double star in Delphinus. It is the nose of the dolphin, located in the northeast corner of the constellation.
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In a telescope, it can make a nice pairing with Struve 2725, which is also a double star, appearing a bit dimmer and perpendicular to Gamma Delphini.
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It forms one corner of the asterism, “Job’s Coffin.”
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On average, when viewed from one, the other would appear as bright as about 100 full moons.
a. Gamma1
Temperature 11,000 °F Diameter 2.9 Suns Spectral Type yellow-white dwarf star (main sequence) B-V Color Index +0.52, yellow Luminosity 12.6 Suns visual Magnitude +2.0 b. Gamma2
Temperature 8,520 °F Diameter 7.68 Suns Spectral Type subgiant B-V Color Index +1.03, orange Luminosity 33 Suns Magnitude +0.95 -
This star has converted all its hydrogen into helium and is on its way to becoming a giant.
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In 1999, a planetary companion was inferred around this star. It would have a minimum mass of 0.7 Jupiter mass, an orbital period of about 1.44 years and about 1.5 AU from the star (about the distance of Mars from our Sun). This inferred planet has not been confirmed.
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References
| Item | Updated | Notes |
| Coordinates | 2002-12-06 | from Scott’s The Flamsteed Collection and close match to SIMBAD |
| Combined Magnitude | 2002-12-06 | from Flamsteed |
| Apparent Separation | 2002-12-06 | from coordinates |
| Distance | 2002-12-06 | from Flamsteed |
| Actual Brightness | 2002-12-06 | from Flamsteed |
| Magnitude | 2002-12-06 | from Flamsteed |
| Mass | -- | |
| Surface Gravity | -- | |
| Surface Composition | 2003-01-06 | OK for all stars |
| Spectral Type | 2002-12-09 | SIMBAD and Flamsteed: gam1 at K1 IV OK.... for gam2, Hipparcos says A2Ia+... while SIMBAD says F7V: going with A2Ia – more recent, and A2 star would dominate any measurement of a F7V star |
| Density | -- | |
| Other Information | 2018-11-20 | http://stars.astro.illinois.edu/sow/gammadel.html https://en.wikipedia.org/wiki/Gamma_Delphini |