2020A&A...641A..43B


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.28CET21:30:45

2020A&A...641A..43B - Astronomy and Astrophysics, volume 641A, 43-43 (2020/9-1)

Is HR 6819 a triple system containing a black hole?. An alternative explanation.

BODENSTEINER J., SHENAR T., MAHY L., FABRY M., MARCHANT P., ABDUL-MASIH M., BANYARD G., BOWMAN D.M., DSILVA K., FROST A.J., HAWCROFT C., REGGIANI M. and SANA H.

Abstract (from CDS):


Context. HR 6819 was recently proposed to be a triple system consisting of an inner B-type giant plus black hole (BH) binary with an orbital period of 40 d and an outer Be tertiary. This interpretation is mainly based on two inferences: that the emission attributed to the outer Be star is stationary and that the inner star, which is used as mass calibrator for the BH, is a B-type giant.
Aims. We re-investigate the properties of HR 6819 to search for a possibly simpler alternative explanation for HR 6819, which does not invoke the presence of a triple system with a BH in the inner binary.
Methods. Based on an orbital analysis, the disentangling of the spectra of the two visible components and the atmosphere analysis of the disentangled spectra, we investigate the configuration of the system and the nature of its components.
Results. Disentangling implies that the Be component is not a static tertiary, but rather a component of the binary in the 40 d orbit. The inferred radial velocity amplitudes of K1=60.4±1.0km/s for the B-type primary and K2=4.0±0.8km/s for the Be-type secondary imply an extreme mass ratio of M2/M1=15±3. We find that the B-type primary, which we estimate to contribute about 45% to the optical flux, has an effective temperature of Teff=16±1kK and a surface gravity of logg=2.8±0.2[cgs], while the Be secondary, which contributes about 55% to the optical flux, has Teff=20±2kK and logg=4.0±0.3[cgs]. We infer spectroscopic masses of 0.4–0.1+0.3M and 6–3+55M for the primary and secondary which agree well with the dynamical masses for an inclination of i=32°. This indicates that the primary might be a stripped star rather than a B-type giant. Evolutionary modelling suggests that a possible progenitor system would be a tight (Pi≃2d) B+B binary system that experienced conservative mass transfer. While the observed nitrogen enrichment of the primary conforms with the predictions of the evolutionary models, we find no indications for the predicted He enrichment .
Conclusions. We suggest that HR 6819 is a binary system consisting of a stripped B-type primary and a rapidly-rotating Be star that formed from a previous mass-transfer event. In the framework of this interpretation, HR 6819 does not contain a BH. Interferometry can distinguish between these two scenarios by providing an independent measurement of the separation between the visible components.

Abstract Copyright: © ESO 2020

Journal keyword(s): stars: massive - stars: early-type - stars: emission-line, Be - binaries: close - binaries: spectroscopic

Simbad objects: 47

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Number of rows : 47

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 * zet Phe Al* 01 08 23.0814982 -55 14 44.728914   3.908 4.014     B6V+B9V 221 0
2 HD 23625 SB* 03 47 52.6640807479 +33 35 59.552064268 6.01 6.674 6.653     B3V+B8.5V 123 0
3 V* IQ Per Al* 03 59 44.6764749090 +48 09 04.489098368   7.77 7.73     B9 141 0
4 HD 33357 Be* 05 11 42.9273627502 +42 09 55.278557789 7.67 8.55 8.55     B1:V:ne 174 0
5 2MASS J05215658+4359220 RG* 05 21 56.5909176121 +43 59 21.957588885           ~ 11 1
6 V* IU Aur bL* 05 27 52.4053853877 +34 46 58.343520392 7.91 8.57 8.39     B3Vnne 170 0
7 V* VV Ori Al* 05 33 31.4472401583 -01 09 21.859507137 4.26 5.16 5.34 5.39 5.59 B9IV/V 240 0
8 HD 37657 Be* 05 42 19.8662288848 +43 03 34.523203698 6.66 7.25 7.25     B3Vne 64 0
9 LS V +22 25 V* 06 11 49.0763076447 +22 49 32.686276490 11.5 11.79 11.51 11.45   B 22 1
10 V* IM Mon bL* 06 23 01.4697825035 -03 16 37.080291418   6.408 6.548     B3V 85 0
11 HD 45995 Be* 06 31 09.5620873293 +11 15 04.958757782 5.20 6.06 6.14     B1.5Vne 144 0
12 V* FZ CMa Al* 07 02 42.6144514495 -11 27 11.571990512 7.71 8.28 8.14     B2IVn 100 1
13 V* LT CMa Al* 07 04 02.6212476630 -12 17 17.372070096 6.74 7.34 7.44     B5III 30 0
14 V* AO Mon Al* 07 06 36.3002058793 -04 37 24.505277598   9.65 9.72     B3+B5 63 1
15 * omi Pup Be* 07 48 05.1683937 -25 56 13.812276 3.42 4.43 4.49 4.37 4.37 B1IVe 202 0
16 V* V Pup bL* 07 58 14.4391988 -49 14 41.680272 3.28 4.24 4.41     B1Vp+B2: 228 0
17 V* RZ Pyx bL* 08 52 04.3971051915 -27 29 01.464387751   9.09 9.17     B5/7p 52 0
18 V* DW Car Al* 10 43 10.0816952047 -60 02 11.743736924 9.02 9.83 9.85 10.03 9.59 B1III 66 0
19 V* SV Cen EB* 11 47 57.2195336815 -60 33 57.757259516 7.98 9.71 9.70 9.46 8.810 B1/3 134 0
20 V* AI Cru Al* 12 06 07.6881742595 -61 15 24.828481075 8.93 9.67 9.69 9.43 9.26 B2IVe 71 0
21 V* V606 Cen bL* 13 21 36.2791258686 -60 31 14.747419547   9.82 9.66 9.78   B1/2Ib/II 43 0
22 * 7 CrB A SB* 15 39 22.6729839797 +36 38 08.917465417   4.871 4.979     B7V 88 0
23 * pi. Sco bL* 15 58 51.1132378 -26 06 50.788602 1.82 2.71 2.91 3.00 3.20 B1V+B2:V: 377 0
24 V* V760 Sco Al* 16 24 43.7186408435 -34 53 37.535017356   7.16 7.05     B4V 147 0
25 * mu.01 Sco bL* 16 51 52.2156925062 -38 02 50.635416093 1.98 2.82 2.98     B1V+B 271 0
26 V* U Oph Al* 17 16 31.7132736201 +01 12 37.996480495   5.941 5.921     B3V 366 1
27 V* V701 Sco WU* 17 34 24.5123986407 -32 30 15.986162640   9.08 8.97     B5 105 0
28 HD 167128 Be* 18 17 07.5317926356 -56 01 24.087624857 4.62 5.30 5.36 5.32 5.36 B3II/III 94 0
29 V* RX Her Al* 18 30 39.2602554603 +12 36 40.324578754   7.35 7.29     A0Vv 176 0
30 V* HS Her Al* 18 50 49.7706078393 +24 43 11.940056707 8.180 8.580 8.560     B6III 112 1
31 HD 175544 SB* 18 55 46.6692340300 +00 15 54.555697142 6.81 7.45 7.35     B3II 47 0
32 V* V599 Aql bL* 19 02 34.1441905514 -10 43 18.392196425 6.41 6.830 6.647     B3II/III 82 0
33 V* V526 Sgr Al* 19 08 15.0261746500 -31 20 54.933029142   9.96 9.82     A0V 59 0
34 * sig Aql bL* 19 39 11.6427715557 +05 23 51.973399317 4.60 5.20 5.17     B3V 163 0
35 HD 191566 SB* 20 09 14.3197158439 +35 29 01.854700169   7.87 7.77 8.58   B0IVp 7 0
36 EM* AS 386 SB* 20 10 54.2006719862 +38 18 09.360772862   11.62 10.95     OB 19 0
37 V* V470 Cyg Al* 20 19 21.7122608286 +40 53 16.456312400   8.737 8.48     B2 63 0
38 V* GO Cyg bL* 20 37 20.1282846896 +35 26 10.290541847   8.64 8.62     A0V 109 0
39 V* V1898 Cyg Al* 21 03 53.7953841858 +46 19 49.922897559 7 7.80 7.82     B2IV 52 0
40 V* V1425 Cyg bL* 21 11 01.7778299784 +55 19 55.979348307   7.79 7.73     B8V 42 0
41 * 18 Peg * 22 00 07.9274510425 +06 43 02.812464798 5.31 5.88 6.00     B3III 103 0
42 * pi. Aqr Be* 22 25 16.6228499 +01 22 38.634579 3.64 4.60 4.64 4.48 4.48 B1III-IVe 388 0
43 HD 215227 Be* 22 42 57.30295 +44 43 18.2525 8.07 8.86 8.81     B1.5-B2III 87 1
44 V* CO Lac Al* 22 46 30.0012980808 +56 49 31.634058719   10.46 10.40     B9V 108 0
45 V* AH Cep bL* 22 47 52.9411821102 +65 03 43.797787196 6.53 7.10 6.88     B0.2V+B2V 206 0
46 V* PV Cas Al* 23 10 02.5753027388 +59 12 06.146578124   9.98 9.86     B6V 144 0
47 HD 222900 EB* 23 44 32.1425749885 +46 22 48.568635810   7.657 7.687 8.52   A0 20 0

    Equat.    Gal    SGal    Ecl

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2020.11.28-21:30:45

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