NGC 637
NGC 637 | |
---|---|
Observation data (J2000.0 epoch) | |
Right ascension | 01h 43m 04.0s[1] |
Declination | +64° 02′ 24″[1] |
Distance | 7.045 ± 1.409 kly (2.160 ± 0.432 kpc)[1] |
Apparent magnitude (V) | 8.2[2] |
Apparent dimensions (V) | 4.2′[3] |
Physical characteristics | |
Estimated age | 10 ± 5 Myr[3] |
Other designations | Cr 17, NGC 637[4] |
Associations | |
Constellation | Cassiopeia |
See also: Open cluster, List of open clusters |
NGC 637 is an open cluster of stars in the northern constellation of Cassiopeia, positioned about 1.5° to the WNW of the star Epsilon Cassiopeiae.[2][5] The cluster was discovered on 9 November 1787 by German-born English astronomer William Herschel.[6] It is located in the Perseus Arm of the Milky Way,[7] at a distance of approximately 7.045 kilolight-years from the Sun.[1] The cluster is small but compact, and is readily visible in a small telescope.[2]
This is a young cluster with an estimated age of 5–15 million years.[3] It has a Trumpler class of I2m, indicating it is strongly concentrated (I) with an intermediate range of brightness variation (2) and a moderate richness of stars (m).[7] The cluster has 55[2] members and an angular radius of 4′.2, corresponding to a physical radius of 9.8 ly (3.0 pc).[7] It has a core radius of 0.36′±0.13′.[8]
The seven brightest members are all over 10th magnitude, with five known to be variable. A total of four β Cephei-type variables have been identified, one of the highest such totals for an open cluster.[9] A classical Be star candidate has been detected.[7] The distribution of the cluster's stars on the Hertzsprung–Russell diagram shows a noticeable gap on the main sequence, which is not explained by missing data.[8]
References
- ^ a b c d Wu, Zhen-Yu; et al. (November 2009). "The orbits of open clusters in the Galaxy". Monthly Notices of the Royal Astronomical Society. 399 (4): 2146–2164. arXiv:0909.3737. Bibcode:2009MNRAS.399.2146W. doi:10.1111/j.1365-2966.2009.15416.x. S2CID 6066790.
- ^ a b c d O'Meara, Steve (June 14, 2007). Herschel 400 Observing Guide. Cambridge University Press. p. 296. ISBN 9780521858939.
- ^ a b c Yadav, R. K. S.; Kumar, Brijesh; Subramaniam, A.; Sagar, Ram; et al. (November 2008). "Optical and near-infrared photometric study of the open cluster NGC 637 and 957". Monthly Notices of the Royal Astronomical Society. 390 (3): 985–996. arXiv:0810.1409. Bibcode:2008MNRAS.390..985Y. doi:10.1111/j.1365-2966.2008.13740.x. S2CID 18096918.
- ^ "NGC 637". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-02-29.
- ^ Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. Vol. 1. Sky Publishing Corporation and the European Space Agency. p. 34. ISBN 0-933346-84-0.
- ^ "New General Catalog Objects: NGC 600 - 649". cseligman.com. Retrieved 2018-01-05.
- ^ a b c d Kharchenko, N. V.; et al. (August 2005). "Astrophysical parameters of Galactic open clusters". Astronomy and Astrophysics. 438 (3): 1163–1173. arXiv:astro-ph/0501674. Bibcode:2005A&A...438.1163K. doi:10.1051/0004-6361:20042523. S2CID 9079873.
- ^ a b Hasan, Priya; et al. (November 2008). "The structure and dynamics of young star clusters: King 16, NGC 1931, NGC 637 and NGC 189". Astrophysics and Space Science. 318 (1–2): 25–33. arXiv:0808.1785. Bibcode:2008Ap&SS.318...25H. doi:10.1007/s10509-008-9888-2. S2CID 18982625.
- ^ Handler, G.; Meingast, S. (September 2011). "New β Cephei stars in the young open cluster NGC 637". Astronomy & Astrophysics. 533: 6. arXiv:1105.3121. Bibcode:2011A&A...533A..70H. doi:10.1051/0004-6361/201116874. S2CID 55061600. A70.
External links
- NGC 637 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
- SEDS
- v
- t
- e
- 500
- 501
- 502
- 503
- 504
- 505
- 506
- 507
- 508
- 509
- 510
- 511
- 512
- 513
- 514
- 515
- 516
- 517
- 518
- 519
- 520
- 521
- 522
- 523
- 524
- 525
- 526
- 527
- 528
- 530
- 531
- 532
- 533
- 534
- 535
- 536
- 537
- 538
- 539
- 540
- 541
- 542
- 543
- 544
- 545
- 546
- 547
- 548
- 549
- 550
- 551
- 552
- 553
- 554
- 555
- 556
- 557
- 558
- 559
- 560
- 561
- 562
- 563
- 564
- 565
- 566
- 567
- 568
- 569
- 570
- 571
- 572
- 573
- 574
- 575
- 576
- 577
- 578
- 579
- 580
- 581
- 582
- 583
- 584
- 585
- 586
- 587
- 588
- 589
- 590
- 591
- 592
- 593
- 594
- 595
- 596
- 597
- 598
- 599
- 600
- 601
- 602
- 603
- 604
- 605
- 606
- 607
- 608
- 609
- 610
- 611
- 612
- 613
- 614
- 615
- 616
- 617
- 618
- 619
- 620
- 621
- 622
- 623
- 624
- 625
- 626
- 627
- 628
- 629
- 630
- 631
- 632
- 633
- 634
- 635
- 636
- 637
- 638
- 639
- 640
- 641
- 642
- 643
- 644
- 645
- 646
- 647
- 648
- 649
- 650
- 651
- 652
- 653
- 654
- 655
- 656
- 657
- 658
- 659
- 660
- 661
- 662
- 663
- 664
- 665
- 666
- 667
- 668
- 669
- 670
- 671
- 672
- 673
- 674
- 675
- 676
- 677
- 678
- 679
- 680
- 681
- 682
- 683
- 684
- 685
- 686
- 687
- 688
- 689
- 690
- 691
- 692
- 693
- 694
- 695
- 696
- 697
- 698
- 699
- 700
- 701
- 702
- 703
- 704
- 705
- 706
- 707
- 708
- 709
- 710
- 711
- 712
- 713
- 714
- 715
- 716
- 717
- 718
- 719
- 720
- 721
- 722
- 723
- 724
- 725
- 726
- 727
- 728
- 729
- 730
- 731
- 732
- 733
- 734
- 735
- 736
- 737
- 738
- 739
- 740
- 741
- 742
- 743
- 744
- 745
- 746
- 747
- 748
- 749
- 750
- 751
- 752
- 753
- 754
- 755
- 756
- 757
- 758
- 759
- 760
- 761
- 762
- 763
- 764
- 765
- 766
- 767
- 768
- 769
- 770
- 771
- 772
- 773
- 774
- 775
- 776
- 777
- 778
- 779
- 780
- 781
- 782
- 783
- 784
- 785
- 786
- 787
- 788
- 789
- 790
- 791
- 792
- 793
- 794
- 795
- 796
- 797
- 798
- 799
- 800
- 801
- 802
- 803
- 804
- 805
- 806
- 807
- 808
- 809
- 810
- 811
- 812
- 813
- 814
- 815
- 816
- 817
- 818
- 819
- 820
- 821
- 822
- 823
- 824
- 825
- 826
- 827
- 828
- 829
- 830
- 831
- 832
- 833
- 834
- 835
- 836
- 837
- 838
- 839
- 840
- 841
- 842
- 843
- 844
- 845
- 846
- 847
- 848
- 849
- 850
- 851
- 852
- 853
- 854
- 855
- 856
- 857
- 858
- 859
- 860
- 861
- 862
- 863
- 864
- 865
- 866
- 867
- 868
- 869
- 870
- 871
- 872
- 873
- 874
- 875
- 876
- 877
- 878
- 879
- 880
- 881
- 882
- 883
- 884
- 885
- 886
- 887
- 888
- 889
- 890
- 891
- 892
- 893
- 894
- 895
- 896
- 897
- 898
- 899
- 900
- 901
- 902
- 903
- 904
- 905
- 906
- 907
- 908
- 909
- 910
- 911
- 912
- 913
- 914
- 915
- 916
- 917
- 918
- 919
- 920
- 921
- 922
- 923
- 924
- 925
- 926
- 927
- 928
- 929
- 930
- 931
- 932
- 933
- 934
- 935
- 936
- 937
- 938
- 939
- 940
- 941
- 942
- 943
- 944
- 945
- 946
- 947
- 948
- 949
- 950
- 951
- 952
- 953
- 954
- 955
- 956
- 957
- 958
- 959
- 960
- 961
- 962
- 963
- 964
- 965
- 966
- 967
- 968
- 969
- 970
- 971
- 972
- 973
- 974
- 975
- 976
- 977
- 978
- 979
- 980
- 981
- 982
- 983
- 984
- 985
- 986
- 987
- 988
- 989
- 990
- 991
- 992
- 993
- 994
- 995
- 996
- 997
- 998
- 999