NGC 3603-A1

Short description: Double-eclipsing binary star system in the constellation Carina

NGC 3603-A1

A1 is the brightest (and top right) of the three barely-resolved stars at the centre in this HST image of the central region of HD 97950.
Credit: NASA, ESA and Wolfgang Brandner (MPIA), Boyke Rochau (MPIA) and Andrea Stolte (University of Cologne)

Observation data
Epoch J2000.0 Equinox (celestial coordinates)
Constellation | Carina
Right ascension |  11h 15m 07.305s[1]
Declination | −61° 15′ 38.43″[1]
Apparent magnitude (V) | 11.18[1]
Characteristics
Spectral type | WN6h+WN6h[2]
B−V color index | 1.03[1]
Variable type | EA[3]
Astrometry
Proper motion (μ)|  RA: 2.4[4] mas/yr
Dec.: 2.8[4] mas/yr
Distance| 7,600[2] pc
Absolute magnitude (MV)| −8.13[2]
Orbit[3]
Primary| A1a
Companion| A2b
Period (P)| 3.7724 days
Eccentricity (e)| 0
Inclination (i)| 71°
Semi-amplitude (K1)
(primary)| 330 ± 20 km/s
Semi-amplitude (K2)
(secondary)| 433 ± 53 km/s
Details
A1a
Mass| 120[2] M☉
Radius| 29[2] R☉
Luminosity| 2,500,000[2] L☉
Temperature| 42,000[2] K
Age| 1.5[2] Myr
A1b
Mass| 92[2] M☉
Radius| 26[2] R☉
Luminosity| 1,500,000[2] L☉
Temperature| 40,000[2] K
Age| 1.5[2] Myr
Other designations

NGC 3603-A1, CD-60°3452A1, CPD-60°2732A1, HD 97950A1, HIP 54948A1, WR 43a, UCAC2 4794917, AAVSO 1110-60, NGC 3603 MDS 30

Database references
SIMBAD| data

NGC 3603-A1 (HD 97950A1) is a double-eclipsing binary star system located at the centre of the HD 97950 cluster in the NGC 3603 star-forming region, about 25,000 light years from Earth. Both stars are of spectral type WN6h and among the most luminous and most massive known.

HD 97950 was catalogued as a star, but was known to be a dense cluster or close multiple star. In 1926, the six brightest members were given letters from A to F,[5] although several of them have since been resolved into more than one star.[6] Star A was first resolved into three components using speckle interferometry, although they can now be directly imaged using space-based or adaptive optics.[1] Component A1 was finally determined to be a spectroscopic binary.[7]

A near-infrared (J band) light curve for NGC 3603-A1, adapted from Moffat et al. (2004)[7]

The two component stars of NGC 3603-A1 circle each other every 3.77 days, and show brightness variations of about 0.3 magnitudes due to eclipses. The stars orbit very close to each other, separated by barely their own diameters and at or near to filling their roche lobes.[7]

The masses of A1a and A1b determined from the orbital parameters are 116 ± 31 M☉ and 89 ± 16 M☉respectively.[3] This makes them the two most massive stars directly measured, i.e. with their masses determined (using Keplerian orbits), and not estimated from models. The masses estimated from analysis of the physical properties are slightly higher at 120 M☉ and 92 M☉.

Each component is a Wolf-Rayet (WR) star, with spectra dominated by strong broadened emission lines. Type WN6 indicates that ionised nitrogen lines are strong in comparison to ionised carbon lines, and the suffix h indicates that hydrogen is also seen in the spectrum. This type of WR star is not the classical stripped helium-burning aged star, but a young highly luminous object with CNO cycle fusion products showing at the surface due to strong conventional and rotational mixing, and high mass loss rates from the atmosphere. The emission lines are generated in the stellar wind and the photosphere is completely hidden. The surface fraction of hydrogen is still estimated to be 60-70%.[2]

Although the stars are very young, around 1.5 million years old, they have already lost a considerable fraction of their initial masses. The initial masses are estimated to have been 148 M☉ and 106 M☉, meaning they have lost 28 M☉ and 14 M☉ respectively.[2]

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 Melena, Nicholas W.; Massey, Philip; Morrell, Nidia I.; Zangari, Amanda M. (2008). "The Massive Star Content of NGC 3603". The Astronomical Journal 135 (3): 878–891. doi:10.1088/0004-6256/135/3/878. ISSN 0004-6256. Bibcode: 2008AJ....135..878M.
2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 Crowther, P. A.; Schnurr, O.; Hirschi, R.; Yusof, N.; Parker, R. J.; Goodwin, S. P.; Kassim, H. A. (2010). "The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 M⊙ stellar mass limit". Monthly Notices of the Royal Astronomical Society 408 (2): 731–751. doi:10.1111/j.1365-2966.2010.17167.x. Bibcode: 2010MNRAS.408..731C.
3. ↑ 3.0 3.1 3.2 Schnurr, O.; Casoli, J.; Chené, A. -N.; Moffat, A. F. J.; St-Louis, N. (2008). "The very massive binary NGC 3603-A1". Monthly Notices of the Royal Astronomical Society: Letters 389 (1): L38–L42. doi:10.1111/j.1745-3933.2008.00517.x. Bibcode: 2008MNRAS.389L..38S.
4. ↑ 4.0 4.1 Zacharias, N. et al. (2004). "The Second U.S. Naval Observatory CCD Astrograph Catalog (UCAC2)". CDS/ADC Collection of Electronic Catalogues 1289 (5): 3043–3059. doi:10.1086/386353. Bibcode: 2003yCat.1289....0Z.
5. ↑ Van Den Bos, W. H. (1928). "Another nebulous multiple star". Bulletin of the Astronomical Institutes of the Netherlands 4: 261. Bibcode: 1928BAN.....4..261V.
6. ↑ Moffat, Anthony F. J.; Drissen, Laurent; Shara, Michael M. (1994). "NGC 3603 and its Wolf-Rayet stars: Galactic clone of R136 at the core of 30 Doradus, but without the massive surrounding cluster halo". Astrophysical Journal 436: 183. doi:10.1086/174891. Bibcode: 1994ApJ...436..183M.
7. ↑ 7.0 7.1 7.2 Moffat, A. F. J.; Poitras, V.; Marchenko, S. V.; Shara, M. M.; Zurek, D. R.; Bergeron, E.; Antokhina, E. A. (2004). "Hubble Space TelescopeNICMOS Variability Study of Massive Stars in the Young Dense Galactic Starburst NGC 3603". The Astronomical Journal 128 (6): 2854–2861. doi:10.1086/425878. ISSN 0004-6256. Bibcode: 2004AJ....128.2854M.

## External links

* NASA Astronomy Picture of the Day: Starburst Cluster in NGC 3603 (5 October 2007)
* NASA Image of the day
* Space Daily

* v
* t
* e

Carina constellation

Stars
(list)|

| Bayer|

* α (Canopus)
* β (Miaplacidus)
* ε (Avior)
* η
* θ
* ι (Aspidiske)
* υ
* χ
* ω

|

Variable|

* R
* S
* T (not variable)
* U
* V
* X
* Y
* RT
* UX
* VY
* WZ
* XY
* XZ
* YZ
* AG
* BO
* CK
* CR
* DW
* EM
* EY
* GG
* GH
* GL
* GZ
* HH
* HR
* IW
* IX
* OY
* PP (p)
* QU
* QX
* QY
* QZ
* V337 (q)
* V341
* V343 (d)
* V344 (f)
* V345 (E)
* V348
* V357 (a)
* V364
* V368
* V369
* V370
* V371 (z2)
* V372
* V374
* V375
* V376 (b1)
* V381
* V382 (x)
* V386
* V390
* V392
* V398
* V399 (P)
* V403
* V409
* V414
* V415 (A)
* V428
* V430
* V431
* V448 (O)
* V450
* V460
* V461
* V469
* V473
* V478
* V482
* V486
* V487
* V492
* V495
* V507
* V514
* V518
* V519
* V520 (w)
* V522
* V524
* V528
* V532
* V533 (y)
* V535
* V557
* V560
* V596
* V640
* V655

HR|

* 2278
* 2400
* 2416
* 2435 (N)
* 2515
* 2523
* 2524
* 2592
* 2634
* 2638
* 2652
* 2661
* 2698
* 2754
* 2767
* 2813
* 2815
* 2862
* 2884
* 2892
* 2925
* 2934 (Q)
* 2941
* 3006
* 3012
* 3031
* 3056
* 3062
* 3070
* 3100
* 3105
* 3120
* 3133
* 3138
* 3139
* 3152
* 3156
* 3159 (D)
* 3161
* 3180
* 3217
* 3218
* 3220 (B)
* 3260 (C)
* 3274
* 3293
* 3298
* 3368
* 3414 (e2)
* 3415 (e1)
* 3432
* 3443
* 3455
* 3471
* 3489
* 3536
* 3549
* 3560
* 3571 (c)
* 3598 (b2)
* 3604
* 3622
* 3632
* 3643 (G)
* 3663 (i)
* 3673
* 3691
* 3693
* 3696 (g)
* 3712
* 3720
* 3721
* 3728 (k)
* 3740
* 3742
* 3752
* 3761
* 3776
* 3777
* 3783
* 3813
* 3821 (H)
* 3825 (h)
* 3856 (m)
* 3863
* 3864
* 3884 (l)
* 3887
* 3913
* 3914
* 3944
* 3957
* 3960
* 3966
* 3967
* 3971
* 3995
* 4002
* 4018
* 4022
* 4025 (M)
* 4043
* 4065
* 4089 (L)
* 4091
* 4095
* 4102 (I)
* 4105
* 4114 (s)
* 4115
* 4120
* 4128
* 4138 (K)
* 4142
* 4144
* 4151
* 4159 (r)
* 4164 (t1)
* 4177 (t2)
* 4179
* 4186
* 4204
* 4205
* 4211
* 4212
* V213
* 4217
* 4219
* 4220
* 4222
* 4226
* 4239
* 4257 (u)
* 4262
* 4266
* 4279
* 4290
* 4323
* 4325 (z1)
* 4326
* 4329
* 4349
* 4355
* 4361
* 4384

HD|

* 49219
* 51608
* 53143
* 54967
* 63765
* 65216
* 79699
* 81896
* 82458
* 84046
* 89805
* 90074
* 90657
* 91094
* 92399
* 92536
* 93129A
* 93250
* 93403
* 93645
* 93695
* 93738
* 93739
* 93843
* 94275
* 94305
* 94491
* 95122
* 96088
* 97950
* 98025

Other|

* BPM 6502
* CPD−57° 2874
* CPD−59° 2628
* CPD−59° 2635
* DEN 0817−6155
* 1E 1048-59
* FO 15
* He 2-38
* Innes' star
* LHS 288
* NGC 3603-A1
* NGC 3603-B
* NGC 3603-C
* OGLE-TR-111
* OGLE-TR-113
* OGLE-TR-122
* OGLE-TR-123
* OGLE-TR-132
* OGLE-TR-182
* OGLE-TR-211
* OGLE2-TR-L9
* PSR J1048-5832
* PSR J1119-6127
* 2S 0921-630
* Sher 25
* SS73 17
* Tr 16-104
* WR 16
* WR 18
* WR 20a
* WR 21a
* WR 22
* WR 23
* WR 24
* WR 25
* WR 30
* WR 30a
* WR 31a
* WR 40
* WR 42e
* AWI0005x3s
* WRA 751

Star
clusters|

| Association|

* Carina OB1
* Carina OB2

|

Open|

* Collinder 228
* IC 2602
* NGC 2516
* NGC 2609
* NGC 3036
* NGC 3114
* NGC 3247
* NGC 3255
* NGC 3293
* NGC 3324
* NGC 3496
* NGC 3519
* NGC 3532
* NGC 3572
* NGC 3590
* NGC 3603
* Trumpler 14
* Trumpler 15
* Trumpler 16
* Westerlund 2

Globular|

* NGC 2808

Nebulae|

| H II|

* Carina Nebula
* NGC 3199
* NGC 3576
* NGC 3579
* NGC 3581
* NGC 3582
* NGC 3584
* NGC 3586
* RCW 49

|

Reflection|

* Homunculus Nebula
* IC 2220
* NGC 3503

Planetary|

* He 2-36
* Hen 2-47
* IC 2448
* IC 2501
* IC 2553
* NGC 2867
* NGC 3211

SNR|

* G290.1-0.8

Pulsar wind|

* IGR J11014−6103

Galaxies|

| NGC|

* 2191
* 2369
* 2369A
* 2369B
* 2381
* 2417
* 2502
* 2640
* 2714
* 2788
* 2822
* 2836
* 2842
* 2887
* 3059
* 3136
* 3136A
* 3136B

|

Other|

* Carina Dwarf Spheroidal Galaxy

Galaxy
clusters|

* Abell 3391
* Abell 3395
* Bullet Cluster

Other|

* GRB 000131
* GRB 080916C

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/NGC 3603-A1. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Astronomy:NGC_3603-A1&oldid=2613439"
*[RA:]: Right Ascension
*[Dec.:]: Declination
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template