Using numerical hydrodynamic simulations, we study the gravitational fragmentation of an unstable protostellar disc formed during the collapse of a pre-stellar core with a mass of 1.2 M ⊙ . The forming fragments span a mass range from about a Jupiter mass to very-low-mass protostars and are located at distances from a few tens to a thousand AU, with a dearth of objects at 100 AU. We explore the possibility of observational detection of the fragments in discs viewed through the outflow cavity at a distance of 250 pc. We demonstrate that one hour of integration time with the Atacama Larger Millimeter/sub-millimeter Array (ALMA) is sufficient to detect the fragments with masses as low as 1.5 M Jup at orbital distances up to 800 AU from the protostar. The ALMA resolution sets the limit on the minimum orbital distance of detectable fragments. For the adopted resolution of our simulated ALMA images of 0.1 ′′ , the fragments can be detected at distances down to 50 AU. At smaller distances, the fragments usually merge with the central density peak. The likelihood for detecting the fragments reduces significantly for a lower resolution of 0.5 ′′ . Some of the most massive fragments, regardless of their orbital distance, can produce characteristic peaks at ≈ 5µm and hence their presence can be indirectly inferred from the observed spectral energy distributions of protostars.

HD 3167 is a bright (V = 8.9 mag) K0 V star observed by NASA's K2 space mission during its Campaign8. It has recently been found to host two small transiting planets, namely, HD 3167b, an ultra-short-period (0.96 days) superEarth, and HD 3167c, a mini-Neptune on a relatively long-period orbit (29.85 days). Here we present an intensive radial velocity (RV) follow-up of HD 3167 performed with the FIES@NOT, HARPS@ESO-3.6 m, and HARPS-N@TNG spectrographs. We revise the system parameters and determine radii, masses, and densities of the two transiting planets by combining the K2 photometry with our spectroscopic data. With a mass of 5.69±0.44 M ⊕ , a radius of 1.574±0.054 R ⊕ , and a mean density of 8.00 0.98-, HD 3167b joins the small group of ultra-short-period planets known to have rocky terrestrial compositions. HD 3167c has a mass of 8. -, indicative of a planet with a composition comprising a solid core surrounded by a thick atmospheric envelope. The rather large pressure scale height (∼350 km) and the brightness of the host star make HD 3167c an ideal target for atmospheric characterization via transmission spectroscopy across a broad range of wavelengths. We found evidence of additional signals in the RV measurements but the currently available data set does not allow us to draw any firm conclusions on the origin of the observed variation.

We report the first confirmation of a hot Jupiter discovered by the Transiting Exoplanet Survey Satellite (TESS ) mission: HD 202772A b. The transit signal was detected in the data from TESS Sector 1, and was confirmed to be of planetary origin through radial velocity (RV) measurements. HD 202772A b is orbiting a mildly evolved star with a period of 3.3 days. With an apparent magnitude of V = 8.3, the star is among the brightest known to host a hot Jupiter. Based on the 27 days of TESS photometry, and RV data from the CHIRON and HARPS spectrographs, the planet has a mass of 1.008 +0.074 −0.079 M J and radius of 1.562 +0.053 −0.069 R J , making it an inflated gas giant. HD 202772A b is a rare example of a transiting hot Jupiter around a quickly evolving star. It is also one of the most strongly irradiated hot Jupiters currently known.

Aims. Our new program with HARPS aims to detect mean motion resonant planetary systems around stars which were previously reported to have a single bona fide planet, often based only on sparse radial velocity data. Methods. Archival and new HARPS radial velocities for the K2V star HD 27894 were combined and fitted with a three-planet self-consistent dynamical model. The best-fit orbit was tested for long-term stability. Results. We find clear evidence that HD 27894 is hosting at least three massive planets. In addition to the already known Jovian planet with a period P b ≈ 18 days we discover a Saturn-mass planet with P c ≈ 36 days, likely in a 2:1 mean motion resonance with the first planet, and a cold massive planet (≈5.3 M Jup ) with a period P d ≈ 5170 days on a moderately eccentric orbit (e d = 0.39). Conclusions. HD 27894 is hosting a massive, eccentric giant planet orbiting around a tightly packed inner pair of massive planets likely involved in an asymmetric 2:1 mean motion resonance. HD 27894 may be an important milestone for probing planetary formation and evolution scenarios.