NGC 1978
| NGC 1978 | |
|---|---|
| Apparent magnitude (V) | 10.12[4] |
| Apparent dimensions (V) | 10.7′ × 3.9′[3] |
| Physical characteristics | |
| Mass | 2×105[5] M☉ |
| Metallicity | = −0.38 ± 0.02 dex |
| = 0.008[6] dex | |
| Estimated age | 1.9 ± 0.1 Gyr[6] |
| Other designations | ESO 85-SC90, KMHK 944 |
![{\displaystyle {\begin{smallmatrix}\left[{\ce {Fe}}/{\ce {H}}\right]\end{smallmatrix}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/4c0821bd80891e071c08e7c7ee8e022baedf522c)
![{\displaystyle {\begin{smallmatrix}\left[{\ce {M}}/{\ce {H}}\right]\end{smallmatrix}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/d9a106d03666c72cc54c1dff07a5637d3adda9a1)
NGC 1978 (also known as ESO 85-SC90) is an elliptical shaped
interstellar extinction.[4] It appears 3.9 arcminutes wide.[8] NGC 1978 has a radial velocity of 293.1 ± 0.9 km/s.[9]
The northwest half of NGC 1978 is iron-rich and younger whereas the southeast part of the cluster has very little iron.[9] NGC 1978 is also highly elliptical (ε ~ 0.30 ± 0.02),[6] suggesting tidal action between it and the Large Magellanic Cloud.[9] It is rich in pulsating asymptotic giant branch stars, often oxygen-rich or carbon-rich.[5] NGC 1978 is about 2 billion years old. Its estimated mass is 1.36×105 M☉, and its total luminosity is 3.41×105 L☉, leading to a mass-to-luminosity ratio of 0.40 M☉/L☉.[4] All else equal, older star clusters have higher mass-to-luminosity ratios; that is, they have lower luminosities for the same mass.[4]
References
- Bibcode:1995A&A...298..427B.
- ^ a b "Globular Cluster NGC 1978". DSO. Retrieved 15 October 2017.
- ^ a b c "The globular cluster NGC 1978". In the sky. Retrieved 22 October 2017.
- ^ .
- ^ S2CID 118506707.
- ^ S2CID 17715270.
- ^ "NGC 1978 (in the Large Magellanic Cloud)". cseligman. Retrieved 16 October 2017.
- ^ "Object: NGC 1978 (*)". SEDS. Retrieved 16 October 2017.
- ^ S2CID 17017344.
External links
Media related to NGC 1978 at Wikimedia Commons
