2013A&A...559A..54V


Query : 2013A&A...559A..54V

2013A&A...559A..54V - Astronomy and Astrophysics, volume 559A, 54-54 (2013/11-1)

The orbits of subdwarf-B + main-sequence binaries. II. Three eccentric systems: BD+29°3070, BD+34°1543 and Feige 87.

VOS J., OSTENSEN R.H., NEMETH P., GREEN E.M., HEBER U. and VAN WINCKEL H.

Abstract (from CDS):

The predicted orbital-period distribution of the subdwarf-B (sdB) population is bi-modal with a peak at short (<10 days) and long (>250 days) periods. Observationally, many short-period sdB systems are known, but the predicted long period peak is missing as orbits have only been determined for a few long-period systems. As these predictions are based on poorly understood binary-interaction processes, it is of prime importance to confront the predictions with reliable observational data. We therefore initiated a monitoring program to find and characterize long-period sdB stars. In this paper we aim to determine the orbital parameters of the three long-period sdB+MS binaries BD+29°3070, BD+34°1543 and Feige87, to constrain their absolute dimensions and the physical parameters of the components. High-resolution spectroscopic time series were obtained with HERMES at the Mercator telescope on La Palma, and analyzed to determine the radial velocities of both the sdB and MS components. Photometry from the literature was used to construct the spectral-energy distribution (SED) of the binaries. Atmosphere models were used to fit these SEDs and to determine the surface gravities and temperatures of both components of all systems. Spectral analysis was used to check the results of the SEDs. An orbital period of 1283±63d, a mass ratio of q=0.39±0.04 and a significant non-zero eccentricity of e=0.15±0.01 were found for BD+29°3070. For BD+34°1543 we determined Porb=972±2d, q=0.57±0.01 and again a clear non-zero eccentricity of e=0.16±0.01. Last, for Feige87 we found Porb=936±2d, q=0.55±0.01 and e=0.11 ±0.01. BD+29°3070, BD+34°1543 and Feige87 are long period sdB + MS binaries on clearly eccentric orbits. These results are in conflict with the predictions of stable Roche-lobe overflow models.

Abstract Copyright:

Journal keyword(s): binaries: spectroscopic - stars: evolution - stars: fundamental parameters - subdwarfs

Simbad objects: 11

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Number of rows : 11
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 BD+34 1543 HS* 07 10 07.7039318016 +34 24 53.808705504   10.29 10.17     sdB+F? 26 0
2 PG 1018-047 HS* 10 21 10.5841130328 -04 56 19.580115516   13.143 13.311     sdB2VIIHe0 25 0
3 Feige 34 HS* 10 39 36.7358839104 +43 06 09.212615280 9.613 10.91 11.14 11.319 11.464 sdOp 654 0
4 PG 1104+243 HS* 11 07 26.2324234560 +24 03 11.108174724   11.49 11.39     sdOB+G2V 27 0
5 Feige 87 HS* 13 40 14.6950103088 +60 52 47.566392996   11.56 11.71     sdB+G4V 38 0
6 PG 1449+653 HS* 14 50 36.0746294472 +65 05 52.012309416   13.57 13.62 13.72   sdB+G5 25 0
7 Balloon 82800003 WD? 15 15 38.3465039784 +56 53 43.746923868   11.57 11.42 11.8   DA/sdB+K1? 11 0
8 PG 1701+359 HS* 17 03 21.4582783560 +35 48 49.223998800   13.41       sdB1VIHe0 30 0
9 BD+29 3070 HS* 17 38 21.2004399672 +29 08 47.348080656   10.55 10.45     sdOB+F/G 25 0
10 BD+28 4211 HS* 21 51 11.0221915656 +28 51 50.367627468 8.922 10.25 10.58 10.656 10.831 sdO2VIIIHe5 775 0
11 BD-07 5977 HS* 23 17 46.7880370560 -06 28 30.941880420   11.09 10.54     sdB 15 0

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2023.01.30-23:10:53

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