00036-3106 HIP 290 is a binary detected by its astrometric acceleration (Makarov & Kaplan 2005, Cat. J/AJ/129/2420) and variable RV (Geneva-Copenhagen Survey; GCS, Nordstroem et al. 2004, see Cat. V/130). The separation implies an orbital period of P^*^=17year.
00164-2235 The faint tertiary companion to HIP 1306 at 1.1'' was first resolved in direct and coronagraphic adaptive-optics (AO) images by Boccaletti et al. (2004PASP..116.1061B), although this is not reflected in the WDS. They quote a separation of 1.075'' and a magnitude difference of 3.5mag at 2.12{mu}m between A and C, but do not list the position angle. Looking at their Figure 9, it is similar to 254{deg} measured here, while we find {Delta}I=4.9mag.
01077-1919 HIP 5291 (HD 6720) was observed because the GCS detected double lines (SB2). However, it is likely that the new 0.6'' companion with {Delta}I=4.8mag is a tertiary.
01380+0946 HIP 7604 (HD 10016) is listed in the GCS as an SB with a mass ratio of 0.960+/-0.010 and [Fe/H] of -0.20. Apparently the SB is resolved here and shows a rapid motion. It was observed by lunar occultations but not resolved (Richichi et al. 2006A&A...445.1081R), and also unresolved by speckle interferometry with the WIYN telescope (Horch et al. 2011, Cat. J/AJ/141/45).
03322-3134 HIP 16481 (HD 22054) is an SB2 with a period of 10.1 days, equal-mass components, and a small eccentricity of 0.13 (Nordstroem et al. 1997, Cat. J/A+AS/126/21). Obviously, the 0.17'' interferometric companion found here cannot correspond to the spectroscopic one, so the system is triple.
06467+0822 HIP 32475 (HD 49015) is a variable star of {gamma} Dor type V839 Mon, an X-ray source, and a 0.3'' visual binary HDS 940. It was observed by speckle interferometry at the WIYN telescope several times (e.g., Horch et al. 2008, Cat. J/AJ/136/312). Re-examination of the WIYN data by one of the authors of this paper (E.H.) shows doubling of the secondary in 2005, 2007, and 2012, confirming its resolution here. The separation of BC implies an orbital period of P^*^~10year; further observational and archival data will soon lead to the determination of its orbit.
10111-7227 The secondary component of HDS 1468 is resolved into the close 63mas pair BC. Its projected separation implies P^*^~20year. Indeed, the pair BC is in rapid retrograde motion, turning by 16{deg} during 2015.
10172-7252 A new component C to HEI 494 AB is discovered at a separation of 0.67''. This component itself is also a 0.07'' binary Ca,Cb. The resolution is confirmed by re-observation in the following runs. The relative position and magnitude difference of Ca,Cb are measured only crudely. If C is physical to AB (the object has a low galactic latitude, so the sky is crowded), this is a new 2+2 quadruple.
10269-5340 HIP 51144 is an SB2 according to the Geneva-Copenhagen Survey (GCS; Nordstroem et al. 2004, see Cat. V/130). It was resolved for the first time at 0.37'' in Run 2 and confirmed in Runs 3 and 9. The projected separation implies P^*^=430year, so the new companion is not the one causing double lines. The system is likely triple. Using Hipparcos photometry, Koen & Eyer 2002 (Cat. J/MNRAS/331/45) found periodic variability with P=1.33 days and an amplitude of 0.03mag.
11106-3234 The pair I 213, known as a binary since 1879, unexpectedly turned out to be a triple system in a nearly equilateral triangular configuration, with two components, B and C, having similar brightness (both are about 3mag fainter than A). It was confirmed on the following night, showing that this is not a transient. This system is discussed in the next subsection.
11596-7813 This is the B9V star {epsilon} Chamaeleontis (HR 4583), the most massive member of the association bearing its name. Known as a binary HJ 4486 AB since 1835, it turns out to be a triple system composed of three similar stars. It is surprising that the inner 50mas pair Aa,Ab was not discovered earlier in high-resolution surveys of the {epsilon} Cha association. The separation implies P^*^~7year, so rapid motion of Aa,Ab is expected. The fringes of Aa,Ab have unit contrast. Processed as a binary, the subsystem Aa,Ab has a magnitude difference of {Delta}y={Delta}I=0.2+/-0.05mag, while the triple-star fit gives a slightly larger {Delta}m. The components Aa and B are also equal and our photometry agrees with the {Delta}Hp_AB_=0.69mag measured by Hipparcos. Note the linear configuration of this triple in Figure 3. The outer pair AB was at (179{deg},1.6'') in 1835 and has now closed down to (235{deg},0.19''). Its nearly radial motion suggests a highly inclined or eccentric orbit. Study of this interesting triple system can give some clues for understanding the peculiarity of this association, which lacks both low-mass stars and wide binaries according to Becker et al. (2013A&A...552A..46B).
16004-5107 HD 143055 (F0V) was observed on request from K. Helminiak. The elongated power spectrum indicates tentative resolution, confirmed in another run. However, the measures are of low accuracy.
18040+0150 According to D. Latham (2012, private communication), HIP 88481=HD 165045 is an SB2 with a period of 1.6 year and a mass ratio of 0.6; its low mass function suggests a face-on orbit. The expected semi-major axis is 46 mas, in agreement with the measured separations and the fast motion of 110{deg}/yr observed over three runs.
19064-1154 The faint secondary of HIP 93827 (HD 177758) is resolved into a 0.25'' pair of equal stars. Their estimated masses are 0.5M_{Sun}_; the period of Ba,Bb is P^*^~30year. This is a solar-type triple system within 67pc.
19512-7248 HIP 97690=HD 186502 (F6V) is an SB2 according to the Geneva-Copenhagen Survey (GCS; Nordstroem et al. 2004, see Cat. V/130). Goldin & Makarov (2007ApJS..173..137G) computed astrometric orbit with P=2.877year, implying a semi-major axis of 28mas. While the separations measured in three runs match the expected axis, the angles disagree with the astrometric orbit; the pair moves very fast.
19563-3137 HIP 98108=HD 188432 (G3V) has double lines (Geneva-Copenhagen Survey; GCS, Nordstroem et al. 2004, see Cat. V/130) and astrometric acceleration. The 80mas separation implies a short period P^*^~7year. The star was not resolved in a survey of astrometric binaries at Gemini-South (Tokovinin et al. 2012, Cat. J/AJ/144/7).
20048+0109 HIP 98878=HD 190412 is a spectroscopic triple with periods of 251 days and 7.8yr (D. Latham 2012, private communication). The outer period corresponds to the axis of 0.10'', and the tertiary was resolved at 0.16''. Astrometric acceleration was also detected. The star is on the exoplanet search program at the Keck telescope.
20286-0426 The Geneva-Copenhagen Survey (GCS; Nordstroem et al. 2004, see Cat. V/130) suspected that HIP 100988 has a variable RV. Its resolution at 0.10'' implies an orbital period P^*^~10yr.
20574-5905 The 4.6'' pair COO 241 AB (HIP 103438) belongs to the 67pc sample. We observed both components separately and resolved the secondary into a new 0.15'' pair Ba,Bb with an estimated period of P^*^~20year. The outer pair has a much longer period of ~40kyr. Desidera et al. (2006A&A...454..553D) detected an RV difference of 2 km/s between A and B, which can partly be caused by the motion of Ba,Bb. The pair Ba,Bb is more massive than the single star A; it is located above the main sequence, as expected for a binary.
22139-2216 HIP 109753 is an SB2 in the GCS. The faint companion at 1.8'' found here could be a tertiary if it is not optical.
22300+0426 This bright star 37 Peg (HR 8566) is a well-known visual binary STF 2912 with an orbital period of 125 yr. Despite the extensive literature, which includes speckle coverage, the binarity of the secondary component has never been suspected. Here it is resolved into a close pair which, projected on the primary, forms an apparently non-hierarchical configuration. The system is further discussed in Section 3.4.
22308-2410 The bright star HIP 111133 (K1III) was resolved by Hipparcos at 0.2'' and has never been confirmed since. Its observation at SOAR shows a change in angle by 6{deg}, while the primary component is a new 53mas pair Aa,Ab. The fringes of Aa, Ab are of high contrast; processing it as a binary gives {Delta}y={Delta}I=0.2+/-0.05mag, while the triple-star fit gives a slightly larger {Delta}m~0.4mag. The period of Aa,Ab is P^*^~40yr. Considering their similar colors, both Aa and Ab are giants at a similar evolutionary stage.
22441+0644 The acceleration binary HIP 112240 (F5) is resolved at 38mas, implying a period of P^*^~2year. The RV variability was detected by the Geneva-Copenhagen Survey (GCS; Nordstroem et al. 2004, see Cat. V/130). It was not resolved in the following run and tentatively resolved again in 2015.7 and 2015.9. All measures are derived by fitting the elongated power spectrum (no second fringe is detected), so they are of questionable accuracy.
23224-4636 HIP 115386 belongs to the 67pc sample. It has a CPM companion at 38.5''. Both components were observed at SOAR. While B was unresolved, we found a new faint pair AC at 1.14''. The sky is not crowded, so AC is likely physical.
23228+2034 HIP 115417B was resolved at the Gemini-North telescope in 2015 (E.H. and A.T., in preparation). It is confirmed here, while the A-component is unresolved. The subsystem Ba,Bb causes a "wobble" with a period of ~115yr in the observed motion of the 5.9'' pair AB.
23296-4001 The known close binary HIP 115987 was observed in the y and I bands. The new faint component C at 0.35'' is seen only in I.