![]() The binary Delorme 1 (AB) is in the center and the companion is the source on the upper right. Credit: NASA/ESA Hubble WFC3; Daniel Apai et al. | |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Phoenix |
Right ascension | 01h 03m 35.6551s |
Declination | −55° 15′ 56.243″ |
Apparent magnitude (V) | 15.40 ±0.05 |
Characteristics | |
Evolutionary stage | red dwarf |
Spectral type | M5/6+M5/6+L0(VLG) [1] |
Variable type | flare star [1] |
Astrometry | |
Radial velocity (Rv) | 5.2 ±1.6 [2] km/s |
Proper motion (μ) | RA: 111.6 ±3.6 mas/yr [2] Dec.: -43.8 ±8.1 mas/yr [2] |
Parallax (π) | 21.18±1.37 mas [3] |
Distance | 154 ± 10 ly (47 ± 3 pc) |
Details [4] | |
Delorme 1A | |
Mass | 0.19 ±0.02 M☉ |
Delorme 1B | |
Mass | 0.17 ±0.02 M☉ |
Position (relative to Delorme 1A) [4] | |
Component | Delorme 1B |
Epoch of observation | 2012 |
Angular distance | 0.249 ±0.003″ |
Projected separation | 12 AU |
Other designations | |
SCR J0103-5515, ** DLR 1AB, DENIS J010335.6-551556, WDS J01036-5516AB, WISE J010335.75-551556.6, 2MASS J01033563-5515561 | |
Database references | |
SIMBAD | data |
Exoplanet Archive | data |
Delorme 1 (2MASS J01033563-5515561) is a binary star with a planetary-mass companion (PMC) or protoplanet in a circumbinary orbit. [4] The PMC is notable for showing signs of accretion, despite being 30-45 Myr old, making it similar to Peter Pan disks. [1] [5] [6] These disks show characteristics of a gas-rich disk at unexpected high ages. [7]
The star was resolved in 2013 with the Very Large Telescope NACO instrument by Delorme et al. A spectrum of the binary was taken with GMOS at Gemini South, which showed a spectral type of M5.5/M6 and strong Hydrogen-alpha emission. The astrometry showed that this star belongs to the Tucana-Horologium association. The binary is separated by around 12 astronomical units (AU). [4] In 2014 Riedel et al. found a better match with the Carina association, which has a similar age as Tuc-Hor. They also found the system to be over-luminous, which might either hint at a younger age or further multiplicity. [3] Other searches do, however, find a better match with Tuc-Hor. [2] Because the Washington Double Star Catalog named the binary ** DLR 1 after the first author of the discovery paper in 2013, Eriksson et al. suggested the name Delorme 1 for the binary. [1] The binary is named after Philippe Delorme. [8]
The binary companion was discovered in 2013 as an object with a mass between 12 and 14 MJ and a separation of 84 AU from the central binary. It had a spectrum similar to early L-dwarfs, but redder than field L-dwarfs. [4] In 2020 Eriksson et al. discovered Hydrogen-alpha, -beta and Helium I lines from Delorme 1 (AB)b using MUSE. This is seen as a clear sign of accretion on a planetary-mass object. The spectral type of this object was determined to be L0 with very low gravity due to stronger than expected vanadium oxide absorption. [1] H-alpha can be influenced by chromospheric activity, complicating its interpretation. Betti et al. discovered Paschen and Brackett lines in Delorme 1 (AB)b in the near-infrared, using TripleSpec at SOAR. These observations are in agreement with planetary-shock accretion. [5] In 2023 Ringqvist et al. observed Delorme 1 (AB)b with the VLT UVES, detecting neutral hydrogen in the ultraviolet. [6] Both near-infrared and ultraviolet observations show an accretion rate of about (about 1.2 to 2.3 the mass of 10 Hygiea per year). [5] [6] The planet and the star were observed with MIRI/IFU, which revealed the circumplanetary disk around the planet. The disk is carbon-rich and contains hydrogen cyanide (HCN), Acetylene (C2H2, tentative: 13CCH2) and molecular hydrogen (H2). The disk has a temperature of 295 ± 27 K (21.9 ± 27.0 °C; 71.3 ± 48.6 °F) and a inner cavity with a size of 32.6±3.1 RJ . According to simulations the disk will only fill out 40% of the Hill radius, resulting of a theoretical disk size of 7.8 AU. The extended emission by H2 is larger than this disk size, showing that it includes an outflow, maybe a disk wind coming from the circumplanetary disk. Assuming a disk wind is present, the disk has a mass-loss rate of 2 × 10−10 MJ/year. [9]
Delorme 1 (AB)b has been called a protoplanet candidate and a super-Jupiter. [5] [6] The researchers found that the high accretion is in better agreement with a formation via disk fragmentation, hinting that it might have formed from a circumstellar disk. [5] Giant planets and brown dwarfs are thought to form via disk fragmentation in rare cases in the outer regions of a disk (r>50 AU). [10] Teasdale et al. modelled three formation scenarios in which the planet could have formed. In the first two scenarios the planet forms in a massive disk via gravitational instability. The first two scenarios produce planets that have accretion and separation comparable to the observed ones, but the resulting planets are more massive than Delorme 1 (AB)b. In a third scenario the planet forms via core accretion in a less massive disk much closer to the binary. In this third scenario the mass and accretion are similar to the observed ones, but the separation is smaller. [11] The modelling of JWST spectrum showed super-solar metallicity and C/O ratio for the planet, but the authors mention that these values are model dependent. The C/O ratio could be consistent with the formation between water and CO snowlines. Alternatively the carbon-rich circumplanetary disk could enrich the planet in carbon, explaining the elevated C/O ratio. [9]
Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (years) | Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | 12 to 14 MJ | 102+47 −27 | 1682+1308 −628 | 0.32+0.27 −0.23 | 127+17 −8 ° | 1.9±0.1 [9] RJ |
68 % confidence range