Two New Long-Period Hot Subdwarf Binaries With Dwarf Companions

Barlow, B. N.; Liss, S.; Wade, Richard A.; Green, Elizabeth M.

doi:10.1088/0004-637x/771/1/23

Cited by 23 publications

(37 citation statements)

References 34 publications

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“…Several long-period eccentric systems (with P ∼ 10 3 d) were recently discovered among sdB stars (Østensen & Van Winckel 2011, 2012Vos et al 2012Vos et al , 2013Deca et al 2012;Barlow et al 2012Barlow et al , 2013. Using new radial-velocity data collected with the HERMES/Mercator spectrograph (Raskin et al 2011), we show in this paper (Sect.…”

Section: Introductionmentioning

confidence: 65%

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IP Eridani: A surprising long-period binary system hosting a He white dwarf

Merle

Jorissen

Masseron

et al. 2014

A&A

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We determine the orbital elements for the K0 IV + white dwarf (WD) system IP Eri, which appears to have a surprisingly long period of 1071 d and a significant eccentricity of 0.25. Previous spectroscopic analyses of the WD, based on a distance of 101 pc inferred from its Hipparcos parallax, yielded a mass of only 0.43 M , implying it to be a helium-core WD. The orbital properties of IP Eri are similar to those of the newly discovered long-period subdwarf B star (sdB) binaries, which involve stars with Heburning cores surrounded by extremely thin H envelopes, and are therefore close relatives to He WDs. We performed a spectroscopic analysis of high-resolution spectra from the HERMES/Mercator spectrograph and concluded that the atmospheric parameters of the K0 component are T eff = 4960 K, log g = 3.3, [Fe/H] = 0.09 and ξ = 1.5 km s −1 . The detailed abundance analysis focuses on C, N, O abundances, carbon isotopic ratio, light (Na, Mg, Al, Si, Ca, Ti) and s-process (Sr, Y, Zr, Ba, La, Ce, Nd) elements. We conclude that IP Eri abundances agree with those of normal field stars of the same metallicity. The long period and non-null eccentricity indicate that this system cannot be the end product of a common-envelope phase; it calls instead for another less catastrophic binary-evolution channel presented in detail in a companion paper.

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Section: Introductionmentioning

confidence: 65%

“…We also include in Fig. 10 the sdB binaries with long periods (black crosses) from Østensen & Van Winckel (2011, 2012, Vos et al (2012Vos et al ( , 2013, Deca et al (2012), and Barlow et al (2012Barlow et al ( , 2013.…”

Section: The Evolutionary Context Of Ip Erimentioning

confidence: 99%

IP Eridani: A surprising long-period binary system hosting a He white dwarf

Merle

Jorissen

Masseron

et al. 2014

A&A

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“…It is very unlikely that this variation is caused by the main-sequence companion. The solved orbits of sdB+MS binaries have long periods of the order of 1000 d (Vos et al 2012(Vos et al , 2013Barlow et al 2012Barlow et al , 2013. We therefore conclude that J205101.72+011259.7 is another candidate for a hierarchical triple system consisting of an sdB in a short-period binary with unseen companion and a main sequence star orbiting this inner binary with a long period (e.g.…”

Section: Hierarchical Triple Systemsmentioning

confidence: 79%

The catalogue of radial velocity variable hot subluminous stars from the MUCHFUSS project

Geier

Kupfer

Heber

et al. 2015

A&A

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The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims to find sdBs with compact companions such as massive white dwarfs, neutron stars, or black holes. Here we provide classifications, atmospheric parameters, and a complete radial velocity (RV) catalogue containing 1914 single measurements for a sample of 177 hot subluminous stars discovered based on SDSS DR7; 110 stars show significant RV variability, while 67 qualify as candidates. We constrain the fraction of close massive compact companions of hydrogen-rich hot subdwarfs in our sample to be smaller than ∼1.3%, which is already close to the theoretical predictions. However, the sample might still contain such binaries with longer periods exceeding ∼8 d. We detect a mismatch between the ΔRV max -distribution of the sdB and the more evolved sdOB and sdO stars, which challenges our understanding of their evolutionary connection. Furthermore, irregular RV variations of unknown origin with amplitudes of up to ∼180 km s −1 on timescales of years, days, and even hours have been detected in some He-sdO stars. They might be connected to irregular photometric variations in some cases.

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“…As argued in Clausen et al (2012), composite systems of the type sdB + early F could be crucial in determining the binary formation channel of hot subdwarfs, depending on the periods measured for these systems. Recently, in Barlow et al (2013) and Vos et al (2013), long period sdB+F/G systems have been reported. It would thus be interesting to know if our sample contains this type of binaries, and to make a follow-up study of them, determining their orbital parameters.…”

Section: Discussionmentioning

confidence: 99%

A search for new hot subdwarf stars by means of virtual observatory tools II

Pérez-Fernández

Solano

Oreiro

et al. 2016

Mon. Not. R. Astron. Soc.

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Recent massive sky surveys in different bandwidths are providing new opportunities to modern astronomy. The Virtual Observatory (VO) represents the adequate framework to handle the huge amount of information available and filter out data according to specific requirements.In this work, we applied a selection strategy to find new, uncatalogued hot subdwarfs making use of VO tools. We used large area catalogues (GALEX, SDSS, SuperCosmos, 2MASS) to retrieve photometric and astrometric information of stellar objects. To these objects, we applied colour and proper motion filters, together with an effective temperature cutoff, aimed at separating hot subdwarfs from other blue objects such as white dwarfs, cataclysmic variables or main sequence OB stars. As a result, we obtained 437 new, uncatalogued hot subdwarf candidates. Based on previous results, we expect our procedure to have an overall efficiency of at least 80 per cent. Visual inspection of the 68 candidates with SDSS spectrum showed that 65 can be classified as hot subdwarfs: 5 sdOs, 25 sdOBs and 35 sdBs. This success rate above 95 per cent proves the robustness and efficiency of our methodology.The spectral energy distribution of 45 per cent of the subdwarf candidates showed infrared excesses, a signature of their probable binary nature. The stellar companions of the binary systems so detected are expected to be late-type main sequence stars. A detailed determination of temperatures and spectral classification of the cool companions will be presented in a forthcoming work.

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Two New Long-Period Hot Subdwarf Binaries With Dwarf Companions

Cited by 23 publications

References 34 publications

IP Eridani: A surprising long-period binary system hosting a He white dwarf

IP Eridani: A surprising long-period binary system hosting a He white dwarf

The catalogue of radial velocity variable hot subluminous stars from the MUCHFUSS project

A search for new hot subdwarf stars by means of virtual observatory tools II

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