Abstract
Planets and brown dwarfs in close orbits will interact with their host stars, as soon as the stars evolve to become red giants. However, the outcome of those interactions is still unclear. Recently, several brown dwarfs have been discovered orbiting hot subdwarf stars at very short orbital periods of 0.065 - 0.096 d. More than 8% of the close hot subdwarf binaries might have sub-stellar companions. This shows that such companions can significantly affect late stellar evolution and that sdB binaries are ideal objects to study this influence. Thirty-eight new eclipsing sdB binary systems with cool low-mass companions and periods from 0.05 to 0.5 d were discovered based on their light curves by the OGLE project. In the recently published catalog of eclipsing binaries in the Galactic bulge, we discovered 75 more systems. We want to use this unique and homogeneously selected sample to derive the mass distribution of the companions, constrain the fraction of sub-stellar companions and determine the minimum mass needed to strip off the red-giant envelope. We are especially interested in testing models that predict hot Jupiter planets as possible companions. Therefore, we started the EREBOS (Eclipsing Reflection Effect Binaries from the OGLE Survey) project, which aims at analyzing those new HW Vir systems based on a spectroscopic and photometric follow up. For this we were granted an ESO Large Program for ESO-VLT/FORS2. Here we give an update on the the current status of the project and present some preliminary results.
References
Baraffe, I., Chabrier, G., Allard, F., and Hauschildt, P. H. 1998, A&A, 337, 403-412.Search in Google Scholar
Barlow, B. N., Kilkenny, D., Drechsel, H., Dunlap, B. H., O’Donoghue, D., Geier, S. et al. 2013, MNRAS, 430, 22-31, 10.1093/mnras/sts27110.1093/mnras/sts271Search in Google Scholar
Charpinet, S., Fontaine, G., Brassard, P., Green, E. M., Van Grootel, V., Randall, S. K. et al. 2011, Nature, 480, 496-499, 10.1038/nature10631 Eggleton, P. P. 1983, ApJ, 268, 368-369, 10.1086/16096010.1038/nature10631Search in Google Scholar PubMed
Geier, S., Schaffenroth, V., Drechsel, H., Heber, U., Kupfer, T., Tillich, A. et al. 2011, APJ, 731(2), L22, 10.1088/2041-8205/731/2/L2210.1088/2041-8205/731/2/L22Search in Google Scholar
Heber, U. 2009, ARA&A, 47, 211-251, 10.1146/annurev-astro-082708-10183610.1146/annurev-astro-082708-101836Search in Google Scholar
Heber, U. 2016, PASP, 128(8), 082001, 10.1088/1538-3873/128/966/08200110.1088/1538-3873/128/966/082001Search in Google Scholar
Jeffery, C. S. and Ramsay, G. 2014, MNRAS, 442, L61-L65, 10.1093/mnrasl/slu05910.1093/mnrasl/slu059Search in Google Scholar
Maxted, P. f. L., Heber, U., Marsh, T. R., and North, R. C. 2001, MNRAS, 326, 1391-1402, 10.1111/j.1365-2966.2001.04714.x10.1111/j.1365-2966.2001.04714.xSearch in Google Scholar
Nelemans, G. and Tauris, T. M. 1998, A&A, 335, L85-L88.Search in Google Scholar
Pietrukowicz, P., Mróz, P., Soszyński, I., Udalski, A., Poleski, R., Szymański, M. K. et al. 2013, Acta Astron., 63, 115-133.Search in Google Scholar
Schaffenroth, V., Geier, S., Drechsel, H., Heber, U., Wils, P., Østensen, R. H. et al. 2013, A&A, 553, A18, 10.1051/0004-6361/20122092910.1051/0004-6361/201220929Search in Google Scholar
Schaffenroth, V., Classen, L., Nagel, K., Geier, S., Koen, C., Heber, U. et al. 2014a, A&A, 570, A70, 10.1051/0004-6361/20142461610.1051/0004-6361/201424616Search in Google Scholar
Schaffenroth, V., Geier, S., Heber, U., Kupfer, T., Ziegerer, E., Heuser, C. et al. 2014b, A&A, 564, A98, doi10.1051/0004-6361/20142337710.1051/0004-6361/201423377Search in Google Scholar
Schaffenroth, V., Barlow, B. N., Drechsel, H., and Dunlap, B. H. 2015, A&A, 576, A123, 10.1051/0004-6361/20152570110.1051/0004-6361/201525701Search in Google Scholar
Silvotti, R., Schuh, S., Janulis, R., Solheim, J.-E., Bernabei, S., Østensen, R. et al. 2007, Nature, 449, 189-191, 10.1038/nature0614310.1038/nature06143Search in Google Scholar PubMed
Silvotti, R., Charpinet, S., Green, E., Fontaine, G., Telting, J. H., Østensen, R. H. et al. 2014, A&A, 570, A130 10.1051/0004-6361/20142450910.1051/0004-6361/201424509Search in Google Scholar
Soker, N. 1998, AJ, 116, 1308-1313, 10.1086/30050310.1086/300503Search in Google Scholar
Soszyński, I., Ste¸pień, K., Pilecki, B., Mróz, P., Udalski, A., Szymański, M. K. et al. 2015, Acta Astron., 65, 39-62.Search in Google Scholar
Soszyński, I., Pawlak, M., Pietrukowicz, P., Udalski, A., Szymański, M. K., Wyrzykowski, L. et al. 2016, Acta Astron., 66, 405-420.Search in Google Scholar
Vučković, M., Østensen, R. H., Németh, P., Bloemen, S., and Pápics, P. I. 2016, A&A, 586, A146, 10.1051/0004-6361/20152655210.1051/0004-6361/201526552Search in Google Scholar
© 2018
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.
