2020A&A...642A.180P

Query : 2020A&A...642A.180P

2020A&A...642A.180P - Astronomy and Astrophysics, volume 642A180-180 (2020/10-1)

Alone but not lonely: Observational evidence that binary interaction is always required to form hot subdwarf stars.

PELISOLI I., VOS J., GEIER S., SCHAFFENROTH V. and BARAN A.S.

Abstract (from CDS):


Context. Hot subdwarfs are core-helium burning stars that show lower masses and higher temperatures than canonical horizontal branch stars. They are believed to be formed when a red giant suffers an extreme mass-loss episode. Binary interaction is suggested to be the main formation channel, but the high fraction of apparently single hot subdwarfs (up to 30%) has prompted single star formation scenarios to be proposed.
Aims. We investigate the possibility that hot subdwarfs could form without interaction by studying wide binary systems. If single formation scenarios were possible, there should be hot subdwarfs in wide binaries that have undergone no interaction.
Methods. Angular momentum accretion during interaction is predicted to cause the hot subdwarf companion to spin up to the critical velocity. The effect of this should still be observable given the timescales of the hot subdwarf phase. To study the rotation rates of companions, we have analysed light curves from the Transiting Exoplanet Survey Satellite for all known hot subdwarfs showing composite spectral energy distributions indicating the presence of a main sequence wide binary companion. If formation without interaction were possible, that would also imply the existence of hot subdwarfs in very wide binaries that are not predicted to interact. To identify such systems, we have searched for common proper motion companions with projected orbital distances of up to 0.1 pc to all known spectroscopically confirmed hot subdwarfs using Gaia DR2 astrometry.
Results. We find that the companions in composite hot subdwarfs show short rotation periods when compared to field main sequence stars. They display a triangular-shaped distribution with a peak around 2.5 days, similar to what is observed for young open clusters. We also report a shortage of hot subdwarfs with candidate common proper motion companions. We identify only 16 candidates after probing 2938 hot subdwarfs with good astrometry. Out of those, at least six seem to be hierarchical triple systems, in which the hot subdwarf is part of an inner binary.
Conclusions. The observed distribution of rotation rates for the companions in known wide hot subdwarf binaries provides evidence of previous interaction causing spin-up. Additionally, there is a shortage of hot subdwarfs in common proper motion pairs, considering the frequency of such systems among progenitors. These results suggest that binary interaction is always required for the formation of hot subdwarfs.

Abstract Copyright: © ESO 2020

Journal keyword(s): subdwarfs - binaries: general - stars: variables: general

VizieR on-line data: <Available at CDS (J/A+A/642/A180): table1.dat table2.dat table3.dat table4.dat>

Simbad objects: 154

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Number of rows : 154
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 SB 7 HS* 00 03 24.4387214592 -16 21 06.386941404   12.6 12.7     sdBHe0+F/G 27 0
2 Ton S 160 HS* 00 31 03.2904428544 -25 35 39.591207996   15.64 15.46 15.73   sdB+F 8 0
3 MCT 0029-4054 HS* 00 31 36.4296552576 -40 37 55.035509448   14.80 14.72 14.78   sdBHe1+F/G 9 0
4 CD-38 222 HS* 00 42 58.3063027488 -38 07 37.291406772   10.19 10.26     sdB 67 0
5 BD-11 162 HS* 00 52 15.0688737672 -10 39 46.074306924 9.987 11.102 11.184 11.133 11.039 sdO+G 48 0
6 EC 00539-8141 HS* 00 54 47.4532104480 -81 25 25.817319948 14.82 15.416 15.136 15.231   sdB+F 6 0
7 JL 219 HS* 00 58 45.8038256496 -56 34 35.308543404   15.26 15.03     sdB+F3 9 0
8 SDSS J010113.32+312555.3 HS* 01 01 13.3379808432 +31 25 55.487223480   12.911 13.030 13.371   sdB 12 0
9 2MASS J01011378+3125589 * 01 01 13.8015798118 +31 25 58.798493319           ~ 1 0
10 PG 0110+262 HS* 01 13 14.8740411528 +26 27 31.247071416   13.000 12.875 12.913   sdB+G0V 26 0
11 CHSS 3354 HS* 01 15 25.8276792288 +19 22 49.096167456     13.09     sdB+F2V 8 0
12 V* EO Cet HS* 01 23 43.2471248112 -05 05 45.831024564   12.21 12.65     sdOV+F4V 68 0
13 EC 01258-7842 HS* 01 26 25.5519592800 -78 26 28.205236248 15.39 16.30 16.30 15.491   sdB+F 9 0
14 Ton S 228 HS* 01 44 22.1246371344 -21 59 37.193599536   14.86 14.78 15.05   sdBHe1+F/G 11 0
15 EC 01437-6247 HS* 01 45 20.0611396056 -62 32 29.086605960   13.996 13.786 13.997   sdB+F 6 0
16 SB 744 HS* 01 48 44.0374557768 -26 36 12.821580144   12.28 12.31     sdO7He1+F/G 53 0
17 FAUST 321 HS* 01 51 23.3904468816 -75 48 38.935891764   13.23 13.03 13.14   sdOB+F 9 0
18 JL 277 HS* 02 01 34.3581667680 -53 43 43.531744944   13.181 13.091 13.352   sdB+G 12 0
19 GALEX J020447.1+272903 HS* 02 04 47.1242783016 +27 29 04.369652628   13.773 13.860 14.089   sdB+G0IV 9 0
20 GALEX J022454.8+010938 HS* 02 24 54.7685738400 +01 09 39.552143292   12.363 12.178 12.251   sdB+F4V 9 0
21 GALEX J023413.1+234211 HS* 02 34 13.2589655760 +23 42 11.247341004   12.57 12.23 12.17   sdB+F 7 0
22 PHL 4265 HS* 02 41 19.8729211320 -20 25 57.388076112   15.576 15.397 15.351   sdB+F 7 0
23 CPD-71 172 ** 02 53 30.6948092520 -71 22 31.730091240   10.82 10.63     F2.5IV+sdOHe-wk 27 0
24 EC 03030-8558 HS* 02 54 42.8892376680 -85 46 23.306080152 13.77 14.30 14.04 14.114   sdB+F 7 0
25 EC 03020-7120 HS* 03 02 14.8217861664 -71 08 38.670089676 15.66 16.285 16.049 15.926   sdB+F 6 0
26 EC 03059-2241 HS* 03 08 09.7674340344 -22 29 51.729339660   16.405 15.990 16.024   sdB+F 7 0
27 EC 03143-5945 HS* 03 15 30.0668968296 -59 34 04.938127608 12.79 13.477 13.376 13.542   sdB 12 0
28 EC 03205-8214 HS* 03 16 57.6855603576 -82 03 58.372218828 13.99 15.074 15.170 15.592   sdB+F 9 0
29 PHL 8667 HS* 03 26 17.3707117416 -06 59 43.945668924   12.805 12.581 12.696   sdB+F 11 0
30 GALEX J033216.7-023302 HS* 03 32 16.7365103928 -02 33 01.870280712   12.88   12.71   sdB+F0V 10 0
31 GALEX J034922.8+271335 HS* 03 49 22.8584472408 +27 13 35.709099276   12.01 11.90     sdB+F 9 0
32 EC 03563-3618 HS* 03 58 14.8297287874 -36 09 38.453063031 13.36 13.918 13.600 13.686   sdB+F 6 1
33 GALEX J041720.6+070816 HS* 04 17 20.6503778040 +07 08 15.065397096           sdB+? 8 0
34 EC 04271-1232 HS* 04 29 29.1170520336 -12 25 38.038555884 13.79 14.263 14.079 14.325   sdB+F 9 0
35 EC 04280-1714 HS* 04 30 18.1812079464 -17 07 41.071553976 13.93 14.75 14.69 14.805   sdB+F 9 0
36 EC 04331-2232 HS* 04 35 14.9835543024 -22 26 42.556095492 14.19 14.579 14.355 14.318   sdB+F 7 0
37 HZ 8 HS? 04 49 08.3322896520 +13 50 00.706116228   14.64 14.54     B3 14 0
38 GALEX J045547.2-203417 HS* 04 55 46.9952825688 -20 34 16.904865936   12.25 12.32     sdB+? 10 0
39 EC 05081-8417 ** 04 59 59.3220710592 -84 13 09.793867944 13.52 13.927 13.494 13.539   F+sd 7 0
40 EC 04578-1524 ** 05 00 07.5897989424 -15 20 21.761690532 12.96 13.495 13.170 13.211   F+sdO? 7 0
41 EC 04598-5519 HS* 05 00 51.5992223664 -55 15 27.011625840 14.13 14.709 14.545 14.558   sdB+F 8 0
42 EC 05003-1808 HS* 05 02 31.5680487816 -18 04 03.520251552 13.17 13.76 13.54 13.62 13.17 sdB+? 7 0
43 2MASS J05033293-2827118 * 05 03 32.9301056132 -28 27 11.862509338           ~ 2 0
44 EC 05015-2831 HS* 05 03 34.4636237376 -28 27 17.248245804 11.67 12.85 12.18     sdOB+F 10 0
45 EC 05133-4632 HS* 05 14 45.9992791296 -46 29 15.215261280 14.75 15.447 15.298 15.510   sdB+F 7 0
46 GALEX J053939.1-283329 HS* 05 39 39.2212782408 -28 33 30.585057156   13.86 13.89 14.15   sdO+G 9 0
47 EC 05576-8527 HS* 05 46 15.0904039008 -85 26 42.564261732 13.10 13.72 13.48 13.590   sdB+F 7 0
48 EC 06031-7744 HS* 06 00 35.5852004976 -77 44 11.460385248 14.29 14.698 14.401 14.600   sdB+F 7 0
49 GALEX J063952.0+515658 HS* 06 39 52.1822938800 +51 57 01.262380032   11.84 12.00     sdBHe1 21 0
50 UCAC4 710-044575 * 06 39 52.9341325782 +51 57 00.608888897       13.834   ~ 2 0
51 2MASS J06544659+2449354 * 06 54 46.5852576729 +24 49 35.392597970           ~ 1 0
52 LAMOST J065446.63+244926.8 HS* 06 54 46.6338671232 +24 49 26.921424144   13.77 13.99 14.30   sdOHe2 11 0
53 GALEX J070812.4+780248 HS* 07 08 12.1927405200 +78 02 48.783291432   12.35 12.12     sdB+F 7 0
54 GALEX J070944.4+750238 HS* 07 09 44.5417342224 +75 02 37.833705816   12.7   12.3   sdB+F 7 0
55 BD+34 1543 HS* 07 10 07.7039318016 +34 24 53.808705504   10.29 10.17     sdB+F? 34 0
56 GALEX J072853.8+534302 HS* 07 28 53.6526647496 +53 43 01.379049312       14.173   sdOB+F3V 12 0
57 GALEX J075010.4-644617 HS* 07 50 10.5184893120 -64 46 18.057484920   14.25 14.09 14.21 13.70 sdB+? 9 0
58 GALEX J082517.9+113107 HS* 08 25 17.9930006808 +11 31 06.306309732   14.583 14.376 14.767   sdB 19 0
59 SDSS J082518.17+113106.1 * 08 25 18.1742061576 +11 31 06.159215316           F8V 3 0
60 GALEX J084210.3-021315 HS* 08 42 10.3160773848 -02 13 16.668616872   13.21 13.05 13.13 12.77 sdB+F0V 9 0
61 US 708 HS* 09 33 20.8631859264 +44 17 05.495440452   18.5 18.8     sdOHe 103 0
62 EC 09319-1339 HS* 09 34 19.6095957600 -13 52 40.068071724   15.4 15.28     sdB+ 9 0
63 EC 10002-1313 HS* 10 02 38.0010429264 -13 27 38.503346112   14.71 14.67     sdB+ 8 0
64 GALEX J101703.6-335502 HS* 10 17 03.6863907960 -33 55 02.340733584   13.11 12.91 13.02   sdB+? 6 0
65 GALEX J102608.5-302615 HS* 10 26 08.4630787512 -30 26 14.221252824   13.17 13.03 13.13   sdB+? 7 0
66 EC 10297-1051 HS* 10 32 15.6005978472 -11 07 16.569993432   14.45 14.21 14.30   sdB+ 9 0
67 EC 10344-2024 HS* 10 36 53.9965222992 -20 40 25.146417540   15.43 15.17     sdB+ 8 0
68 HE 1038-2326 HS* 10 40 36.8674785744 -23 42 39.592377972   15.80 15.77 16.03   sdB 11 0
69 EC 10405-1347 HS* 10 43 00.2709445992 -14 03 34.826639580   15.22 15.04     sdB+ 8 0
70 EC 10583-2057 HS* 11 00 46.7168730960 -21 13 11.546590188   15.73 15.46     sdB+ 8 0
71 GALEX J110055.9+105542 HS* 11 00 55.9516210776 +10 55 42.328549164   14.05 14.16 14.65   sdB 15 0
72 UCAC4 505-053396 * 11 00 55.9867022693 +10 55 33.700047171       16.197   ~ 6 0
73 EC 11001-2506 HS* 11 02 32.2672094760 -25 22 26.199496560   15.17 15.03     sdB+ 8 0
74 EC 11022-1357 HS* 11 04 45.7434862248 -14 14 11.938526412   13.02 12.88     sdB+A 9 0
75 GALEX J110743.0-373158 HS* 11 07 43.1774512224 -37 31 58.863017352   13.03 12.55     sdB+? 7 0
76 PG 1109-070 SB* 11 11 36.2970547608 -07 18 32.389666272   14.54 14.46 14.72   ~ 12 0
77 CD-26 8759B * 11 45 28.1357921687 -27 18 22.171427424           ~ 1 0
78 CD-26 8759 HS* 11 45 28.6082223300 -27 18 23.517281847   11.592 11.351 11.494   sdB+ 10 0
79 EC 11446-3204 HS* 11 47 10.2122106672 -32 21 30.477723732   12.86 12.74     sdB+ 8 0
80 V* V551 Hya HS* 12 00 54.6503605776 -27 24 44.948207556   14.47 14.41     sdB+ 16 0
81 GALEX J130551.3-365700 HS* 13 05 51.3249855408 -36 56 59.557617024   12.45 12.26     sdB+? 6 0
82 Feige 87 HS* 13 40 14.6950103088 +60 52 47.566392996   11.56 11.71     sdB+G4V 49 0
83 2MASS J14082944+5940587 * 14 08 29.4361191356 +59 40 59.156906613           ~ 2 0
84 Feige 91 HS* 14 08 32.2307108736 +59 40 25.466557728   13.199 13.418 13.777   sdB 36 0
85 GALEX J141133.4+703736 HS* 14 11 33.4347322752 +70 37 37.377301800   12.94 13.21     sdB+F0.5V 8 0
86 PG 1411+590 HS* 14 13 12.4377704112 +58 46 11.242308252   15.68   16.21   sdB 13 0
87 PG 1411+590B * 14 13 12.5736155736 +58 46 09.647533812           ~ 1 0
88 GALEX J144208.8-224008 HS* 14 42 08.7756864120 -22 40 09.111884232   13.37 13.19 13.35 12.75 sdB+? 6 0
89 PG 1449+653 HS* 14 50 36.0746294472 +65 05 52.012309416   13.57 13.62 13.72   sdB+G5 30 0
90 GALEX J150412.3+763046 HS* 15 04 12.3625499664 +76 30 44.523104688   13.42 12.98     sdB+? 6 0
91 GALEX J151325.7+645407 HS* 15 13 26.1177839256 +64 54 06.760083816   13.912 13.799 14.021   sdB+G0V 7 1
92 Balloon 82800003 WD? 15 15 38.3465039784 +56 53 43.746923868   11.57 11.42 11.8   DA/sdB+K1? 16 0
93 PG 1524+611 HS* 15 25 13.3930898688 +60 53 22.559645436   12.94 12.71 12.92   sdOB 14 0
94 PG 1612+736 SB* 16 12 06.2449494960 +73 27 57.301789896   14.55 14.474     ~ 13 1
95 PG 1618+563B Em* 16 19 26.5988937384 +56 05 58.593549588   12.16 12.34 12.71   F3 20 1
96 PG 1618+563 HS* 16 19 26.9188578888 +56 06 01.009178568       13.93   sdB0VIIHe8 31 2
97 2MASS J16252428+3830147 * 16 25 24.2902765994 +38 30 14.728226560           ~ 1 0
98 PG 1623+386 HS* 16 25 24.2940110208 +38 30 18.880122708   15.69 15.63     sdB 21 0
99 GALEX J163811.0+621717 HS* 16 38 10.6283999400 +62 17 16.972420164   13.67 13.56 13.69   sdB+? 10 0
100 GALEX J172125.7+090311 HS* 17 21 25.7645436744 +09 03 11.283852348   15.522 15.425 15.538   sdB 12 0
101 2MASS J17212601+0903080 * 17 21 26.0139787470 +09 03 08.122476459           ~ 1 0
102 HS 1753+7025 HS? 17 53 20.8787397264 +70 25 33.947120604   15.50 15.37     ~ 10 0
103 GALEX J182025.6-642758 HS* 18 20 25.4217057648 -64 27 59.683407660   13.72 13.49 13.57 13.14 sdB+? 5 0
104 HS 1858+5736 HS* 18 59 47.0851660056 +57 40 32.971886616   14.991 14.969 15.006   sdO+F5V 11 0
105 UCAC4 658-070326 HS* 19 02 49.9649497656 +41 34 58.055577024   13.786 14.086 14.264   sdOB 10 0
106 2MASS J19025077+4134451 * 19 02 50.7826782677 +41 34 45.055148617           ~ 1 0
107 GALEX J191453.8-534332 HS* 19 14 53.8701216480 -53 43 31.792990656   13.28 13.15   12.80 sdB+? 6 0
108 BPS CS 22947-0281 HS* 19 32 58.6048813464 -51 01 27.621130008 13.02 13.725 13.570 13.603   sdB+? 8 0
109 EC 19304-5337 HS* 19 34 24.8853277872 -53 30 27.921127932 14.33 14.81 14.60     sdB+F 9 0
110 EC 19327-5656 ** 19 36 50.0487521472 -56 50 09.917996028 15.63 16.238 16.049 15.971   F+sd? 7 0
111 EC 19420-5836 HS* 19 46 15.1741622256 -58 29 17.519197128 14.00 14.938 14.850 14.997   sdB+F 10 0
112 BPS CS 22873-0006 HS* 19 47 57.0033207792 -60 55 39.463855140 13.48 14.07 13.88     sdB+F? 7 0
113 EC 19472-4342 ** 19 50 48.3341152176 -43 34 37.132756824 15.40 15.884 16.074 16.067   F+sd? 7 0
114 EC 20132-7317 ** 20 18 52.0469581656 -73 08 36.046587336 12.07 12.50 12.19 12.19 11.62 F2+sd? 11 0
115 EC 20287-5534 HS* 20 32 38.2839586968 -55 24 29.987308944 14.10 14.952 14.940 14.911   sdB+F 9 0
116 EC 20358-2708 HS* 20 38 50.5067011128 -26 57 54.264940524 11.62 12.26 11.85     sdO+G3.5III 11 0
117 EC 20385-3332 HS* 20 41 40.5716218656 -33 21 44.978729580     13.5 13.462   sdB+? 7 0
118 BPS CS 30314-0163 HS* 20 42 34.2218008416 -35 17 30.820623432 13.45 14.118 13.904 13.968   sdB+ 8 0
119 BPS CS 30314-0078 HS* 20 51 45.6426685896 -36 36 54.910354968 13.77 14.30 14.06 14.16   sdB+ 8 0
120 EC 21079-3548 HS* 21 11 03.4782024552 -35 35 52.831945140 13.06 13.610 13.34 13.257   sdB+F 8 0
121 BPS CS 22937-0067 HS* 21 12 17.5404809256 -38 20 54.561137532 13.14 13.97 13.91     sdB+F 8 0
122 BPS CS 30492-0126 HS* 21 18 50.7016324224 -41 30 49.616594604 14.290 15.14 14.9     sdB+G 12 0
123 EC 21235-4808 HS* 21 26 53.5649061888 -47 55 17.972169456 13.94 14.524 14.373 14.418   sdB+F 7 0
124 EC 21373-3727 HS* 21 40 22.9012396872 -37 14 15.798439320 12.12 12.57 12.84     sdB+F6V 9 0
125 GALEX J214233.8-294858 HS* 21 42 33.8037510768 -29 48 59.239528812   13.01 12.79 12.88   sdB+? 6 0
126 EC 21425-7923 ** 21 48 22.8432222048 -79 09 20.035956168 15.88 16.180 15.935     F+sd? 8 0
127 EC 21462-2209 ** 21 49 01.5506150026 -21 55 49.403768503 14.68 15.364 15.207 15.272   F3+sd 7 0
128 EC 21565-2111 ** 21 59 20.4088593792 -20 56 46.140321984   14.195 13.960 14.214   F+sd? 6 0
129 HE 2156-3927 HS* 21 59 35.5062919224 -39 13 15.015645264     15.06     sdB+K3 12 0
130 EC 22081-1916 HS* 22 10 52.8672227976 -19 01 49.632538512   12.82 12.94 13.30   sdB 19 0
131 EC 22212-5915 HS* 22 24 33.7068682128 -59 00 43.819162344 14.40 14.946 14.661 14.637   sdB+F 6 0
132 PHL 5267 HS? 22 32 26.8323127776 -20 19 15.999093660   12.654 12.410 12.484   ~ 8 0
133 BPS CS 22875-0025 HS* 22 33 10.7917927224 -39 44 41.157977748   14.82 14.80     sdB+F 16 0
134 EC 22336-3606 ** 22 36 28.6221620088 -35 51 09.092383920   16.279 16.098 16.034   F+sd 7 0
135 EC 22340-6720 HS* 22 37 35.6811083904 -67 05 08.197980216 14.97 15.635 15.441 15.954   sdB+F 7 0
136 EC 22374-3419 HS* 22 40 16.8413835696 -34 03 28.553250492       14.467   sdB+F 9 0
137 2MASS J22482499+2714360 * 22 48 24.9868629934 +27 14 36.070038722           ~ 1 0
138 GALEX J224825.0+271447 HS* 22 48 25.0522950936 +27 14 47.511892068   13.25 13.15 13.10   sdB+? 4 0
139 FBS 2253+335 HS* 22 55 58.1872043160 +33 43 11.797198896   12.63 12.61     sdB 17 0
140 UCAC4 619-130885 * 22 55 59.7029424996 +33 42 53.920528866   13.781 13.026 12.962   ~ 1 0
141 EC 22540-3324 HS* 22 56 48.8244668232 -33 08 25.780838172   14.048 13.856 14.014   sdB/sdOB? 8 0
142 KPD 2254+5444 HS* 22 57 02.6544437712 +55 00 13.433683104 13.49 14.46 14.37 14.54   sdB 13 0
143 2MASS J22570272+5500168 * 22 57 02.7440276602 +55 00 16.761741530           ~ 2 0
144 EC 23123-2942 HS* 23 15 04.6245438120 -29 26 06.190020888   15.069 14.794 15.069   sdB+F 8 0
145 JL 129 HS* 23 15 51.9827972208 -82 55 24.487942260 13.17 13.97 13.68     sdB+F 9 0
146 EC 23129-6802 ** 23 16 02.5566332352 -67 45 38.911208688 14.93 15.653 15.435 15.626   F0+sdB? 7 0
147 EC 23205-1832 HS* 23 23 08.1136151832 -18 15 45.382854384   15.351 15.133 15.240   sdB+F 7 0
148 HE 2322-4559 HS* 23 25 08.9659312272 -45 43 05.482553880   15.5       sdB+G4 10 0
149 JL 135 HS* 23 25 58.1871438936 -71 27 26.931970368 13.86 14.59 14.52     sdB+F 11 0
150 EC 23317-7354 HS* 23 34 48.3476539104 -73 38 05.019267804 13.29 14.131 13.969 14.228   sdB+F 9 0
151 Ton S 111 HS* 23 42 41.4167798640 -27 50 01.757927904   14.87 15.01 15.35   sdBHe1+F/G? 14 0
152 BPS CS 29499-0052 ** 23 49 57.6691611648 -23 23 54.253735620   14.728 14.390 14.400   F4+sd? 8 0
153 BPS CS 29517-0017 HS* 23 53 12.3528316536 -17 08 59.826415956     14.4     sdBHe0+F/G 10 0
154 Ton S 131 HS* 23 59 07.1389258440 -26 38 39.934916844     13.5     sdBHe0+F/G 20 0

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