Skip to content
BY 4.0 license Open Access Published by De Gruyter Open Access April 20, 2019

A small survey of UV-bright stars around the northern ecliptic pole: seeking new p-mode sdB variables for the TESS mission

  • Saskia Prins EMAIL logo , John Telting and Roy Østensen
From the journal Open Astronomy

Abstract

Starting in 2019, the TESS mission will monitor the northern ecliptic pole for 1 year. Data will be collected at 30-minute and 2-minute cadences, and only a limited amount of slots will be reserved for targets requiring a 20- second cadence. Only the 20-second cadence is sufficient to sample p-mode oscillations in sdB stars. From the seismic measurements obtained with the Kepler spacecraft we have gained a wealth of new insights in structural and rotational aspects of mainly g-mode variable sdB stars. Unfortunately only one traditional p-mode sdB variable was found in the main Kepler field. The TESS mission offers the opportunity to obtain more long-time-base coverage of p-mode sdB variables, especially at the ecliptic poles where the time-base will be longest. Thus far, there were only two known (p-mode) sdBVs around the northern ecliptic pole > 78): LS Dra and V366 Dra. In this paper we describe our efforts to find more.We compiled a new sample of 76 sdB candidates around the northern ecliptic pole, based on GALEX and optical colours, and we used low-resolution Balmer-line spectroscopy for classification. We identified 39 new sdB stars, of which 29 have characteristics (Teff > 28000 K or a composite spectrum) that may put them in the p-mode instability strip.With our 39 new sdB stars, we augmented the number of known sdB stars in the the northern ecliptic pole area (β> 73) by 46%. Besides these sdB stars, among our spectral classifications are various sdO stars, He-sdB stars, blue horizontal-branch stars, white dwarfs, cataclysmic variables and main sequence B stars. We obtained time-resolved photometry of most of the p-mode sdB candidates, and found one new sdBV, J19384+5824, with a moderately high pulsation amplitude of ≥ 9 mmag.

References

Baran A. S., Reed, M. D., Stello, D., Østensen, R. H., Pakštienë, E. et al., 2012, MNRAS 424, 2686–2700.10.1111/j.1365-2966.2012.21355.xSearch in Google Scholar

Bertin, E. & Arnouts, S. 1996, A&AS, 317, 393–404.Search in Google Scholar

Bianchi, L., Conti, A., & Shiao, B., 2014, GALEX-GR6/7 data release, VizieR Online Data Catalog, 2335.Search in Google Scholar

Edelmann, H., Heber, U.,Hagen, H.-J., Lemke, M., Dreizler, S., Napiwotzki, R. et al., 2003, A&A, 400, 939–950.10.1051/0004-6361:20030135Search in Google Scholar

Kilkenny, D., Koen, C., O’Donoghue, D., & Stobie, R. S. 1997, MNRAS, 285, 640–644.Search in Google Scholar

Geier S., Østensen R. H., Nemeth, P., Gentile Fusillo, N. P., G´’ansicke, B. T., Telting, J. H. et al. 2017, A&A 600, A50.Search in Google Scholar

Holdsworth, D. L., Østensen, R. H., Smalley, B., & Telting, J. H. 2017, MNRAS, 466, 5020–5032.Search in Google Scholar

Østensen, R.H., Oreiro, R., Solheim, J.-E., Heber, U., Silvotti, R., González-Pérez, J. M. et al. 2010, A&A, 513, A6.Search in Google Scholar

Raskin, G., Bloemen, S., Morren, J., Perez Padilla, J., Prins, S., Pessemier, W. et al. 2013, A&A, 559, A26.Search in Google Scholar

Reed M.D., Baran, A. S., Telting, J. H., Ó stensen, R. H., Jeffery, C. S.; Kern, J. W. et al. 2018, OAstro, 27, 157–166.Search in Google Scholar

Ricker, G. R., Winn, J. N., Vanderspek, R., Latham, D. W., Bakos, G. Á., Bean, J. L. et al. 2015, JATIS, 1, 014003.Search in Google Scholar

Telting, J. H., Baran, A. S, Østensen, R. H., Kupfer, T., Macfarlane, S., Heber, U. et al. 2014, A&A 570, A129.Search in Google Scholar

Zong, W., Charpinet, S., & Vauclair, G. 2016, A&A, 594, A4610.1051/0004-6361/201629132Search in Google Scholar

Received: 2017-09-29
Accepted: 2017-11-15
Published Online: 2019-04-20

© 2019 Saskia Prins et al., published by De Gruyter Open

This work is licensed under the Creative Commons Attribution 4.0 Public License.

Downloaded on 29.3.2024 from https://www.degruyter.com/document/doi/10.1515/astro-2019-0005/html
Scroll to top button