M 73 ( Messier 73 , Messier 73 , other designations - NGC 6994 , OCL 89 ) - asterism in the constellation Aquarius .
| M 73 | |
|---|---|
| Star cluster | |
 | |
| Research history | |
| Discoverer | Charles Messier |
| opening date | October 4, 1780 |
| Designations | M 73 , Messier 73 , Messier 73 , NGC 6994 , OCL 89 |
| Observational data ( Age J2000.0 ) | |
| Type of | Type IV1p open cluster |
| Right ascension | |
| Declination | |
| Distance | and |
| Visible magnitude (V) | 8.9 |
| Visible Dimensions (V) | 1.4 ' |
| Constellation | Aquarius |
This object is one of those listed in the original edition of the New General Catalog .
Content
- 1 Observations
- 1.1 Neighbors in the sky from the Messier catalog
- 1.2 Sequence of observation at the Messier Marathon
- 2 See also
- 3 notes
- 4 Literature
- 5 Links
Observations
Object M 73 is located in the western part of the constellation Aquarius east of the globular cluster M 72 . M 73 is just four stars of 10-12 magnitude within a tight circle with a diameter of about 1 arc minute. It is not completely clear whether all these four stars are physically connected (gravitationally and by origin) or are accidentally projected onto this compact region of the sky. Research in this group is ongoing.
This asterism should be sought almost exactly in the middle of the line from μ Aquarius to θ Capricorn (30 arc minutes north-north-west of the star 6.5m). For observation, use a telescope with an aperture of 125-150 mm and magnifications of 60x.
Usually one observes the globular globular cluster M 72 and the very interesting planetary nebula NGC 7009 at 2 degrees northeast (about a degree west of ν Aquarius 4.5m). This nebula is called "Saturn" and the name surprisingly fits it - it looks like a compact rounded disk with "ears" on the sides. It is better to prepare a search map for all these dim and unusual objects before observations.
Neighbors in the Sky from Messier Catalog
- M 72 - (one and a half degrees to the west) the most dim globular cluster in the Messier catalog;
- M 30 - (in the east of Capricorn) a rather bright and large globular cluster;
- M 75 - (to the southwest, in Sagittarius) a moderately bright globular cluster, far from landmarks;
- M 2 - (to the northeast) a bright and extremely dense globular cluster;
Sequence of Observation at the Messier Marathon
... M 72 → M 75 → M 73 → M 2 → M 55 ...
See also
- List of Messier objects
- New shared directory
Notes
- ↑ Pandey AK, Sandhu TS, Sagar R. et al. Integrated parameters of star clusters: a comparison of theory and observations // Mon. Not. R. Astron. Soc. / D. Flower - OUP , 2010 .-- Vol. 403. - P. 1491-1506. - ISSN 0035-8711 ; 1365-2966 - doi: 10.1111 / j.1365-2966.2009.16213.x
Literature
- M. Odenkirchen, C. Soubiran. NGC 6994 - clearly not a physical stellar ensemble // arXiv: astro-ph. - 2001.
Links
- Information in English and French from the original “ New General Catalog ”
- Information (Eng.) From the Revised New General Catalog
- SIMBAD
- VizieR (English)
- NASA / IPAC Extragalactic Database
- NGC 6994 Publication List