Trumpler classification system

Transcription

1 Tonight s Novice topic is: An overview of the Trumpler classification system il d b i l Compiled by Jim Wessel Johnson Space Center Astronomical Society

2 Shapley s Classification scheme a. Field Irregularities - features irregular star counts and associations. They differ from the normal distribution of stars, being more closely concentrated yet not enough to be studied. b. Star Associations - This category contains clusters that have distantly spaced stars sharing the same motion. e.g. Ursa Major group c. Very Loose and Irregular Clusters These are very large and scattered clusters. e.g. Pleiades, Hyades, and the alpha Persei group. d. Loose Clusters - very small amounts of stars and appear loose. Shapley gave M21 and M34 as examples of this type. e. Intermediate Rich & Concentrated compact and concentrated. e.g. M38 f. Fairly Rich and Concentrated - This group is as compact as the e group, yet with more stars; e.g. M37 g. Considerably Rich and Concentrated - This group is similarly compact as group f, yet contains more stars; the Jewel Box (NGC 4755) is in this class.

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4 OC / Trumpler Classification system talk Robert Julius Trumpler Swiss born, American Astronomer Allegheny Obs -> Lick Obs. -> Berkeley Independently discovered the absorption of light by interstellar dust (Boris Vorontsov- Velyaminov independently also found this). Introduced term Galactic Clusters in Elected to the National Academy of Sciences in His classification system is the most commonly used means of identifying OCs today. In 1930, he created a table of 37 Open Clusters that are now known n as the Trumpler Catalog.

5 Trumpler Classification System Degree of concentration I. Detached clusters with strong central concentration. II. Detached clusters with little central concentration. III. Detached clusters with no noticeable concentration. IV. Not well detached from surrounding star field. Range of brightness 1. Most of the cluster stars are nearly the same apparent brightness. 2. Moderate range in brightness. 3. Cluster is composed of bright and faint stars. Number of stars in cluster p = Poor (less than 50 stars). m = Medium rich ( stars). r = Rich (more than 100 stars).

6 Brightness for all 12 blocks is 2 or 3 Concentration of cluster Bernhard Hubl, Nu mber of stars in the cluste r

7 Degree of concentration I. Detached clusters with strong central concentration. I 3 r I 2r

8 Degree of concentration II. Detached clusters with little central concentration. II 2 r II 2r

9 Degree of concentration III. Detached clusters with no noticeable concentration. III 2 m III 1 r

10 Degree of concentration IV. Not well detached from surrounding star field. IV 3 m IV 2 r

11 Range of brightness 1. Most of the cluster stars are nearly the same apparent brightness. 1 I m 1 I r

12 Range of brightness 2. Moderate range in brightness. 2 2 II r I r

13 Range of brightness 3. Cluster is composed of bright and faint stars. 3 II r 3 I m

14 Number of stars in cluster p = Poor (less than 50 stars). IV 2 p I 3 p

15 Number of stars in cluster m = Medium rich ( stars). III 2 m I 3 m n

16 Number of stars in cluster r = Rich (more than 100 stars). Both are I3r r II 2 r

17 The letter 'n following the Trumpler type means that there is nebulosity associated with the cluster. II 3 r n I 2 r n

18 Audience participation: Degree of Concentration: I. Detached cluster w/ strong central concentration ti Range of brightness II. Detached cluster w/ some 1. Number Most central of stars stars concentration are in about cluster the same apparent brightness III. p = Detached Poor (less cluster than 50 w/ stars) no 2. Moderate noticeable range concentration of brightness m = Mdi Medium rich ih(50100 ( stars) IV. 3. Cluster Not well is detached composed from of both r = bright surrounding Rich (more and faint than star stars field 100 stars) NGC 5617 Pismis 19 = = I 3 r I 1 r

19 Audience participation: M 73 = Degree of Concentration: I. Detached cluster w/ Range of brightness strong central concentration 1. Most stars are about the same II. Detached cluster w/ some Number apparent of stars brightness in cluster central concentration ti 2. p = Moderate Poor (less range than of 50 brightness stars) III. Detached cluster w/ no noticeable concentration m 3. = Cluster Mdi Medium is composed rich ih(50100 ( of both stars) bright and faint stars IV. Not well detached from r = Rich (more than 100 stars) surrounding star field IV 1 p

20 Audience participation: M 45 = Degree of Concentration: I. Detached cluster w/ Range strong of brightness central concentration ti II. 1. Most Detached stars cluster are about w/ the some same Number apparent central of stars concentration brightness in cluster Note: this image does III. 2. p not = Moderate Detached show Poor (less edge range cluster than of of 50 w/ cluster brightness stars) no stars noticeable concentration 3. m = Cluster Medium is composed rich ( of both stars) IV. bright Not well and detached faint stars from r = surrounding Rich (more than star field 100 stars) The letter 'n following the Trumpler type means that there is nebulosity associated with the cluster. I 3 r n

21 Why Observe Open Clusters? 1. They are always available, year round. 2. They aren t as susceptible to light pollution as other deep objects like nebulae and galaxies. 3. Quite a few of them are needed to complete the Messier observing list. 4. The Astronomy League s Open Cluster observing club.

22 Astrophotography credits and associated websites Anthony Ayiomamitis M 45 Christopher Abissi - NGC 559, NGC 6791, NGC org/index php Scott Alder - NGC 4755 Canada, France, Hawaii Telescope NGC 2158, NGC Jon Christensen Double Cluster (NGC 869 & NGC 884) Jon Christensen Double Cluster (NGC 869 & NGC 884)

23 Astrophotography credits and associated websites (continued) The Digitized Sky Survey (1 & 2) Berkeley 29 John Drummond - Hyades Robert Gendler - NGC t Martin Germano NGC 1502, NGC 1817, M 73 Hubblesite.org (various contributors) NGC 265, NGC 290

24 Astrophotography credits and associated websites (continued) Bernhard Hubl Composite Trumpler Classification image, NGC 129, DoDz 9, NGC 6793, NGC 7169, NGC 5617 and Pismis 19, Al Kelly IC 188, NGC 457, NGC 6819, Dean Rowe Tombaugh 4 Jim Thommes NGC 1342, NGC t Daniel Verschatse NGC

25 Trumpler Classification system novice talk Sources used for this presentation were: Wikipedia, Publications of the Astronomical Society of the Pacific, Vol. 69, No. 409, p , ster/

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27 Trumpler Classification System Degree of concentration I. Detached clusters with strong central concentration. II. Detached clusters with little central concentration. III. Detached clusters with no noticeable concentration. IV. Not well detached from surrounding star field. Range of brightness 1. Most of the cluster stars are nearly the same apparent brightness. 2. Moderate range in brightness. 3. Cluster is composed of bright and faint stars. Number of stars in cluster p = Poor (less than 50 stars). m = Medium rich ( stars). r = Rich (more than 100 stars).

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