Delorme 1

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Delorme 1 (AB)
Delorme 1 (AB)b HST WFC3.jpg
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]
ComponentDelorme 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]

Contents

The binary system

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 circumstellar companion

JWST MIRI IFU image, showing the molecular hydrogen outflow of the planet at 9.665 mm in violet Delorme 1 (AB)b JWST MIRI IFU.jpg
JWST MIRI IFU image, showing the molecular hydrogen outflow of the planet at 9.665 μm in violet

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]

The Delorme 1 (AB) planetary system [4] [12]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(years)
Eccentricity Inclination Radius
b12 to 14  MJ 102+47
−27
1682+1308
−628
0.32+0.27
−0.23
127+17
−8
°
1.9±0.1 [9]   RJ

References

  1. 1 2 3 4 5 Eriksson, Simon C.; Asensio Torres, Rubén; Janson, Markus; Aoyama, Yuhiko; Marleau, Gabriel-Dominique; Bonnefoy, Mickael; Petrus, Simon (2020-06-01). "Strong Halpha emission and signs of accretion in a circumbinary planetary mass companion from MUSE". Astronomy and Astrophysics. 638: L6. arXiv: 2005.11725 . Bibcode:2020A&A...638L...6E. doi:10.1051/0004-6361/202038131. ISSN   0004-6361. S2CID   218870278.
  2. 1 2 3 4 Gagné, Jonathan; Lafrenière, David; Doyon, René; Malo, Lison; Artigau, Étienne (2015-01-01). "BANYAN. V. A Systematic All-sky Survey for New Very Late-type Low-mass Stars and Brown Dwarfs in Nearby Young Moving Groups". The Astrophysical Journal. 798 (2): 73. arXiv: 1410.4864 . Bibcode:2015ApJ...798...73G. doi:10.1088/0004-637X/798/2/73. ISSN   0004-637X.
  3. 1 2 Riedel, Adric R.; Finch, Charlie T.; Henry, Todd J.; Subasavage, John P.; Jao, Wei-Chun; Malo, Lison; Rodriguez, David R.; White, Russel J.; Gies, Douglas R.; Dieterich, Sergio B.; Winters, Jennifer G.; Davison, Cassy L.; Nelan, Edmund P.; Blunt, Sarah C.; Cruz, Kelle L. (2014-04-01). "The Solar Neighborhood. XXXIII. Parallax Results from the CTIOPI 0.9 m Program: Trigonometric Parallaxes of Nearby Low-mass Active and Young Systems". The Astronomical Journal. 147 (4): 85. arXiv: 1401.0722 . Bibcode:2014AJ....147...85R. doi:10.1088/0004-6256/147/4/85. ISSN   0004-6256.
  4. 1 2 3 4 5 6 Delorme, P.; Gagné, J.; Girard, J. H.; Lagrange, A. M.; Chauvin, G.; Naud, M. -E.; Lafrenière, D.; Doyon, R.; Riedel, A.; Bonnefoy, M.; Malo, L. (2013-05-01). "Direct-imaging discovery of a 12-14 Jupiter-mass object orbiting a young binary system of very low-mass stars". Astronomy and Astrophysics. 553: L5. arXiv: 1303.4525 . Bibcode:2013A&A...553L...5D. doi: 10.1051/0004-6361/201321169 . ISSN   0004-6361.
  5. 1 2 3 4 5 Betti, S. K.; Follette, K. B.; Ward-Duong, K.; Aoyama, Y.; Marleau, G. -D.; Bary, J.; Robinson, C.; Janson, M.; Balmer, W.; Chauvin, G.; Palma-Bifani, P. (2022-08-01). "Near-infrared Accretion Signatures from the Circumbinary Planetary-mass Companion Delorme 1 (AB)b". The Astrophysical Journal. 935 (1): L18. arXiv: 2208.05016 . Bibcode:2022ApJ...935L..18B. doi: 10.3847/2041-8213/ac85ef . ISSN   0004-637X.
  6. 1 2 3 4 Ringqvist, Simon C.; Viswanath, Gayathri; Aoyama, Yuhiko; Janson, Markus; Marleau, Gabriel-Dominique; Brandeker, Alexis (2023-01-01). "Resolved near-UV hydrogen emission lines at 40-Myr super-Jovian protoplanet Delorme 1 (AB)b. Indications of magnetospheric accretion". Astronomy and Astrophysics. 669: L12. arXiv: 2212.03207 . Bibcode:2023A&A...669L..12R. doi:10.1051/0004-6361/202245424. ISSN   0004-6361.
  7. Silverberg, Steven M.; Wisniewski, John P.; Kuchner, Marc J.; Lawson, Kellen D.; Bans, Alissa S.; Debes, John H.; Biggs, Joseph R.; Bosch, Milton K. D.; Doll, Katharina; Luca, Hugo A. Durantini; Enachioaie, Alexandru; Hamilton, Joshua; Holden, Jonathan; Hyogo, Michiharu; the Disk Detective Collaboration (2020-01-14). "Peter Pan Disks: Long-lived Accretion Disks Around Young M Stars". The Astrophysical Journal. 890 (2): 106. arXiv: 2001.05030 . Bibcode:2020ApJ...890..106S. doi: 10.3847/1538-4357/ab68e6 . S2CID   210718358.
  8. "Members of the Exoplanets team". IPAG - Institut de Planétologie et d’Astrophysique de Grenoble. Retrieved 2024-08-27.
  9. 1 2 3 Mâlin, Mathilde; Ward-Duong, Kimberly; Grant, Sierra L.; Arulanantham, Nicole; Tabone, Benoît; Pueyo, Laurent; Perrin, Marshall; Balmer, William O.; Betti, Sarah; Chen, Christine H.; Debes, John H.; Girard, Julien H.; Hoch, Kielan K. W.; Kammerer, Jens; Lu, Cicero; Rebollido, Isabel; Rickman, Emily; Robinson, Connor; Worthen, Kadin; van der Marel, Roeland P.; Lewis, Nikole K.; Seager, Sara; Valenti, Jeff A.; Soummer, Remi (2025). "JWST-TST High Contrast: Medium-resolution spectroscopy reveals a carbon-rich circumplanetary disk around the young accreting exoplanet Delorme 1 AB b". arXiv: 2510.07253 [astro-ph.EP].
  10. Rice, Ken; Lopez, Eric; Forgan, Duncan; Biller, Beth (2015-12-01). "Disc fragmentation rarely forms planetary-mass objects". Monthly Notices of the Royal Astronomical Society. 454 (2): 1940–1947. arXiv: 1508.06528 . Bibcode:2015MNRAS.454.1940R. doi: 10.1093/mnras/stv1997 . ISSN   0035-8711.
  11. Teasdale, Matthew; Stamatellos, Dimitris (2024-08-01). "On the potential origin of the circumbinary planet Delorme 1 (AB)b". Monthly Notices of the Royal Astronomical Society. 533 (2): 2294–2302. arXiv: 2408.06231 . Bibcode:2024MNRAS.533.2294T. doi: 10.1093/mnras/stae1964 . ISSN   0035-8711.
  12. Blunt, Sarah; Nielsen, Eric L.; De Rosa, Robert J.; Konopacky, Quinn M.; Ryan, Dominic; Wang, Jason J.; Pueyo, Laurent; Rameau, Julien; Marois, Christian; Marchis, Franck; Macintosh, Bruce; Graham, James R.; Duchêne, Gaspard; Schneider, Adam C. (2017-05-01). "Orbits for the Impatient: A Bayesian Rejection-sampling Method for Quickly Fitting the Orbits of Long-period Exoplanets". The Astronomical Journal. 153 (5): 229. arXiv: 1703.10653 . Bibcode:2017AJ....153..229B. doi: 10.3847/1538-3881/aa6930 . ISSN   0004-6256. 68 % confidence range