TESS and CHEOPS discover two warm sub-Neptunes transiting the bright K-dwarf HD 15906

A Tuson; D Queloz; H P Osborn; T G Wilson; M J Hooton; M Beck; M Lendl; G Olofsson; A Fortier; A Bonfanti; A Brandeker; L A Buchhave; A Collier Cameron; D R Ciardi; K A Collins; D Gandolfi; Z Garai; S Giacalone; J Gomes da Silva; S B Howell; J A Patel; C M Persson; L M Serrano; S G Sousa; S Ulmer-Moll; A Vanderburg; C Ziegler; Y Alibert; R Alonso; G Anglada; T Bárczy; D Barrado Navascues; S C C Barros; W Baumjohann; T Beck; W Benz; N Billot; X Bonfils; L Borsato; C Broeg; J Cabrera; S Charnoz; D M Conti; Sz Csizmadia; P E Cubillos; M B Davies; M Deleuil; L Delrez; O D S Demangeon; B-O Demory; D Dragomir; C D Dressing; D Ehrenreich; A Erikson; Z Essack; J Farinato; L Fossati; M Fridlund; E Furlan; H Gill; M Gillon; C L Gnilka; E Gonzales; M Güdel; M N Günther; S Hoyer; K G Isaak; J M Jenkins; L L Kiss; J Laskar; D W Latham; N Law; A Lecavelier des Etangs; G Lo Curto; C Lovis; R Luque; D Magrin; A W Mann; P F L Maxted; M Mayor; S McDermott; M Mecina; C Mordasini; A Mortier; V Nascimbeni; R Ottensamer; I Pagano; E Pallé; G Peter; G Piotto; D Pollacco; T Pritchard; R Ragazzoni; N Rando; F Ratti; H Rauer; I Ribas; G R Ricker; M Rieder; N C Santos; A B Savel; G Scandariato; R P Schwarz; S Seager; D Ségransan; A Shporer; A E Simon; A M S Smith; M Steller; C Stockdale; Gy M Szabó; N Thomas; G Torres; R Tronsgaard; S Udry; B Ulmer; V Van Grootel; R Vanderspek; J Venturini; N A Walton; J N Winn; B Wohler

doi:10.1093/mnras/stad1369

TESS and CHEOPS discover two warm sub-Neptunes transiting the bright K-dwarf HD 15906

A Tuson^*, D Queloz, H P Osborn, T G Wilson, M J Hooton, M Beck, M Lendl, G Olofsson, A Fortier, A Bonfanti, A Brandeker, L A Buchhave, A Collier Cameron, D R Ciardi, K A Collins, D Gandolfi, Z Garai, S Giacalone, J Gomes da Silva, S B HowellJ A Patel, C M Persson, L M Serrano, S G Sousa, S Ulmer-Moll, A Vanderburg, C Ziegler, Y Alibert, R Alonso, G Anglada, T Bárczy, D Barrado Navascues, S C C Barros, W Baumjohann, T Beck, W Benz, N Billot, X Bonfils, L Borsato, C Broeg, J Cabrera, S Charnoz, D M Conti, Sz Csizmadia, P E Cubillos, M B Davies, M Deleuil, L Delrez, O D S Demangeon, B-O Demory, D Dragomir, C D Dressing, D Ehrenreich, A Erikson, Z Essack, J Farinato, L Fossati, M Fridlund, E Furlan, H Gill, M Gillon, C L Gnilka, E Gonzales, M Güdel, M N Günther, S Hoyer, K G Isaak, J M Jenkins, L L Kiss, J Laskar, D W Latham, N Law, A Lecavelier des Etangs, G Lo Curto, C Lovis, R Luque, D Magrin, A W Mann, P F L Maxted, M Mayor, S McDermott, M Mecina, C Mordasini, A Mortier, V Nascimbeni, R Ottensamer, I Pagano, E Pallé, G Peter, G Piotto, D Pollacco, T Pritchard, R Ragazzoni, N Rando, F Ratti, H Rauer, I Ribas, G R Ricker, M Rieder, N C Santos, A B Savel, G Scandariato, R P Schwarz, S Seager, D Ségransan, A Shporer, A E Simon, A M S Smith, M Steller, C Stockdale, Gy M Szabó, N Thomas, G Torres, R Tronsgaard, S Udry, B Ulmer, V Van Grootel, R Vanderspek, J Venturini, N A Walton, J N Winn, B Wohler

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Abstract

We report the discovery of two warm sub-Neptunes transiting the bright (G = 9.5 mag) K-dwarf HD 15906 (TOI 461, TIC 4646810). This star was observed by the Transiting Exoplanet Survey Satellite (TESS) in sectors 4 and 31, revealing two small transiting planets. The inner planet, HD 15906 b, was detected with an unambiguous period but the outer planet, HD 15906 c, showed only two transits separated by ∼ 734 d, leading to 36 possible values of its period. We performed follow-up observations with the CHaracterising ExOPlanet Satellite (CHEOPS) to confirm the true period of HD 15906 c and improve the radius precision of the two planets. From TESS, CHEOPS, and additional ground-based photometry, we find that HD 15906 b has a radius of 2.24 ± 0.08 R_⊕ and a period of 10.924709 ± 0.000032 d, whilst HD 15906 c has a radius of 2.93\^\+0.07\\-0.06\\ R_⊕ and a period of 21.583298\^\+0.000052\\-0.000055\\ d. Assuming zero bond albedo and full day-night heat redistribution, the inner and outer planet have equilibrium temperatures of 668 ± 13 K and 532 ± 10 K, respectively. The HD 15906 system has become one of only six multiplanet systems with two warm (≲ 700 K) sub-Neptune sized planets transiting a bright star (G ≤ 10 mag). It is an excellent target for detailed characterization studies to constrain the composition of sub-Neptune planets and test theories of planet formation and evolution.

Original language	English
Pages (from-to)	3090-3118
Number of pages	29
Journal	Monthly Notices of the Royal Astronomical Society
Volume	523
Issue number	2
Early online date	8 Jun 2023
DOIs	https://doi.org/10.1093/mnras/stad1369
Publication status	Published - Aug 2023

Keywords

techniques: photometric
planets and satellites: detection
planets and satellites: fundamental parameters
stars: fundamental parameters
stars: individual: HD 15906 (TOI 461, TIC 4646810)

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TusonA2023TESSFinal published version, 9.65 MBLicence: Creative Commons: Attribution (CC BY)

https://doi.org/10.1093/mnras/stad1369Licence: Creative Commons: Attribution (CC BY)

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Tuson, A., Queloz, D., Osborn, H. P., Wilson, T. G., Hooton, M. J., Beck, M., Lendl, M., Olofsson, G., Fortier, A., Bonfanti, A., Brandeker, A., Buchhave, L. A., Collier Cameron, A., Ciardi, D. R., Collins, K. A., Gandolfi, D., Garai, Z., Giacalone, S., Gomes da Silva, J., ... Wohler, B. (2023). TESS and CHEOPS discover two warm sub-Neptunes transiting the bright K-dwarf HD 15906. Monthly Notices of the Royal Astronomical Society, 523(2), 3090-3118. https://doi.org/10.1093/mnras/stad1369

@article{99fd1fce8aa14d9c89babbd8eaf2645d,

title = "TESS and CHEOPS discover two warm sub-Neptunes transiting the bright K-dwarf HD 15906",

abstract = "We report the discovery of two warm sub-Neptunes transiting the bright (G = 9.5 mag) K-dwarf HD 15906 (TOI 461, TIC 4646810). This star was observed by the Transiting Exoplanet Survey Satellite (TESS) in sectors 4 and 31, revealing two small transiting planets. The inner planet, HD 15906 b, was detected with an unambiguous period but the outer planet, HD 15906 c, showed only two transits separated by ∼ 734 d, leading to 36 possible values of its period. We performed follow-up observations with the CHaracterising ExOPlanet Satellite (CHEOPS) to confirm the true period of HD 15906 c and improve the radius precision of the two planets. From TESS, CHEOPS, and additional ground-based photometry, we find that HD 15906 b has a radius of 2.24 ± 0.08 R⊕ and a period of 10.924709 ± 0.000032 d, whilst HD 15906 c has a radius of 2.93\^\+0.07\\-0.06\\ R⊕ and a period of 21.583298\^\+0.000052\\-0.000055\\ d. Assuming zero bond albedo and full day-night heat redistribution, the inner and outer planet have equilibrium temperatures of 668 ± 13 K and 532 ± 10 K, respectively. The HD 15906 system has become one of only six multiplanet systems with two warm (≲ 700 K) sub-Neptune sized planets transiting a bright star (G ≤ 10 mag). It is an excellent target for detailed characterization studies to constrain the composition of sub-Neptune planets and test theories of planet formation and evolution.",

keywords = "techniques: photometric, planets and satellites: detection, planets and satellites: fundamental parameters, stars: fundamental parameters, stars: individual: HD 15906 (TOI 461, TIC 4646810)",

author = "A Tuson and D Queloz and Osborn, {H P} and Wilson, {T G} and Hooton, {M J} and M Beck and M Lendl and G Olofsson and A Fortier and A Bonfanti and A Brandeker and Buchhave, {L A} and A Collier Cameron and Ciardi, {D R} and Collins, {K A} and D Gandolfi and Z Garai and S Giacalone and J Gomes da Silva and Howell, {S B} and Patel, {J A} and Persson, {C M} and Serrano, {L M} and Sousa, {S G} and S Ulmer-Moll and A Vanderburg and C Ziegler and Y Alibert and R Alonso and G Anglada and T B{\'a}rczy and D Barrado Navascues and Barros, {S C C} and W Baumjohann and T Beck and W Benz and N Billot and X Bonfils and L Borsato and C Broeg and J Cabrera and S Charnoz and Conti, {D M} and Sz Csizmadia and Cubillos, {P E} and Davies, {M B} and M Deleuil and L Delrez and Demangeon, {O D S} and B-O Demory and D Dragomir and Dressing, {C D} and D Ehrenreich and A Erikson and Z Essack and J Farinato and L Fossati and M Fridlund and E Furlan and H Gill and M Gillon and Gnilka, {C L} and E Gonzales and M G{\"u}del and G{\"u}nther, {M N} and S Hoyer and Isaak, {K G} and Jenkins, {J M} and Kiss, {L L} and J Laskar and Latham, {D W} and N Law and A Lecavelier des Etangs and Curto, {G Lo} and C Lovis and R Luque and D Magrin and Mann, {A W} and Maxted, {P F L} and M Mayor and S McDermott and M Mecina and C Mordasini and A Mortier and V Nascimbeni and R Ottensamer and I Pagano and E Pall{\'e} and G Peter and G Piotto and D Pollacco and T Pritchard and R Ragazzoni and N Rando and F Ratti and H Rauer and I Ribas and Ricker, {G R} and M Rieder and Santos, {N C} and Savel, {A B} and G Scandariato and Schwarz, {R P} and S Seager and D S{\'e}gransan and A Shporer and Simon, {A E} and Smith, {A M S} and M Steller and C Stockdale and Szab{\'o}, {Gy M} and N Thomas and G Torres and R Tronsgaard and S Udry and B Ulmer and V Van Grootel and R Vanderspek and J Venturini and Walton, {N A} and Winn, {J N} and B Wohler",

year = "2023",

month = aug,

doi = "10.1093/mnras/stad1369",

language = "English",

volume = "523",

pages = "3090--3118",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "SIPRI/Oxford University Press",

number = "2",

}

Tuson, A, Queloz, D, Osborn, HP, Wilson, TG, Hooton, MJ, Beck, M, Lendl, M, Olofsson, G, Fortier, A, Bonfanti, A, Brandeker, A, Buchhave, LA, Collier Cameron, A, Ciardi, DR, Collins, KA, Gandolfi, D, Garai, Z, Giacalone, S, Gomes da Silva, J, Howell, SB, Patel, JA, Persson, CM, Serrano, LM, Sousa, SG, Ulmer-Moll, S, Vanderburg, A, Ziegler, C, Alibert, Y, Alonso, R, Anglada, G, Bárczy, T, Barrado Navascues, D, Barros, SCC, Baumjohann, W, Beck, T, Benz, W, Billot, N, Bonfils, X, Borsato, L, Broeg, C, Cabrera, J, Charnoz, S, Conti, DM, Csizmadia, S, Cubillos, PE, Davies, MB, Deleuil, M, Delrez, L, Demangeon, ODS, Demory, B-O, Dragomir, D, Dressing, CD, Ehrenreich, D, Erikson, A, Essack, Z, Farinato, J, Fossati, L, Fridlund, M, Furlan, E, Gill, H, Gillon, M, Gnilka, CL, Gonzales, E, Güdel, M, Günther, MN, Hoyer, S, Isaak, KG, Jenkins, JM, Kiss, LL, Laskar, J, Latham, DW, Law, N, Lecavelier des Etangs, A, Curto, GL, Lovis, C, Luque, R, Magrin, D, Mann, AW, Maxted, PFL, Mayor, M, McDermott, S, Mecina, M, Mordasini, C, Mortier, A, Nascimbeni, V, Ottensamer, R, Pagano, I, Pallé, E, Peter, G, Piotto, G, Pollacco, D, Pritchard, T, Ragazzoni, R, Rando, N, Ratti, F, Rauer, H, Ribas, I, Ricker, GR, Rieder, M, Santos, NC, Savel, AB, Scandariato, G, Schwarz, RP, Seager, S, Ségransan, D, Shporer, A, Simon, AE, Smith, AMS, Steller, M, Stockdale, C, Szabó, GM, Thomas, N, Torres, G, Tronsgaard, R, Udry, S, Ulmer, B, Van Grootel, V, Vanderspek, R, Venturini, J, Walton, NA, Winn, JN & Wohler, B 2023, 'TESS and CHEOPS discover two warm sub-Neptunes transiting the bright K-dwarf HD 15906', Monthly Notices of the Royal Astronomical Society, vol. 523, no. 2, pp. 3090-3118. https://doi.org/10.1093/mnras/stad1369

TY - JOUR

T1 - TESS and CHEOPS discover two warm sub-Neptunes transiting the bright K-dwarf HD 15906

AU - Tuson, A

AU - Queloz, D

AU - Osborn, H P

AU - Wilson, T G

AU - Hooton, M J

AU - Beck, M

AU - Lendl, M

AU - Olofsson, G

AU - Fortier, A

AU - Bonfanti, A

AU - Brandeker, A

AU - Buchhave, L A

AU - Collier Cameron, A

AU - Ciardi, D R

AU - Collins, K A

AU - Gandolfi, D

AU - Garai, Z

AU - Giacalone, S

AU - Gomes da Silva, J

AU - Howell, S B

AU - Patel, J A

AU - Persson, C M

AU - Serrano, L M

AU - Sousa, S G

AU - Ulmer-Moll, S

AU - Vanderburg, A

AU - Ziegler, C

AU - Alibert, Y

AU - Alonso, R

AU - Anglada, G

AU - Bárczy, T

AU - Barrado Navascues, D

AU - Barros, S C C

AU - Baumjohann, W

AU - Beck, T

AU - Benz, W

AU - Billot, N

AU - Bonfils, X

AU - Borsato, L

AU - Broeg, C

AU - Cabrera, J

AU - Charnoz, S

AU - Conti, D M

AU - Csizmadia, Sz

AU - Cubillos, P E

AU - Davies, M B

AU - Deleuil, M

AU - Delrez, L

AU - Demangeon, O D S

AU - Demory, B-O

AU - Dragomir, D

AU - Dressing, C D

AU - Ehrenreich, D

AU - Erikson, A

AU - Essack, Z

AU - Farinato, J

AU - Fossati, L

AU - Fridlund, M

AU - Furlan, E

AU - Gill, H

AU - Gillon, M

AU - Gnilka, C L

AU - Gonzales, E

AU - Güdel, M

AU - Günther, M N

AU - Hoyer, S

AU - Isaak, K G

AU - Jenkins, J M

AU - Kiss, L L

AU - Laskar, J

AU - Latham, D W

AU - Law, N

AU - Lecavelier des Etangs, A

AU - Curto, G Lo

AU - Lovis, C

AU - Luque, R

AU - Magrin, D

AU - Mann, A W

AU - Maxted, P F L

AU - Mayor, M

AU - McDermott, S

AU - Mecina, M

AU - Mordasini, C

AU - Mortier, A

AU - Nascimbeni, V

AU - Ottensamer, R

AU - Pagano, I

AU - Pallé, E

AU - Peter, G

AU - Piotto, G

AU - Pollacco, D

AU - Pritchard, T

AU - Ragazzoni, R

AU - Rando, N

AU - Ratti, F

AU - Rauer, H

AU - Ribas, I

AU - Ricker, G R

AU - Rieder, M

AU - Santos, N C

AU - Savel, A B

AU - Scandariato, G

AU - Schwarz, R P

AU - Seager, S

AU - Ségransan, D

AU - Shporer, A

AU - Simon, A E

AU - Smith, A M S

AU - Steller, M

AU - Stockdale, C

AU - Szabó, Gy M

AU - Thomas, N

AU - Torres, G

AU - Tronsgaard, R

AU - Udry, S

AU - Ulmer, B

AU - Van Grootel, V

AU - Vanderspek, R

AU - Venturini, J

AU - Walton, N A

AU - Winn, J N

AU - Wohler, B

PY - 2023/8

Y1 - 2023/8

N2 - We report the discovery of two warm sub-Neptunes transiting the bright (G = 9.5 mag) K-dwarf HD 15906 (TOI 461, TIC 4646810). This star was observed by the Transiting Exoplanet Survey Satellite (TESS) in sectors 4 and 31, revealing two small transiting planets. The inner planet, HD 15906 b, was detected with an unambiguous period but the outer planet, HD 15906 c, showed only two transits separated by ∼ 734 d, leading to 36 possible values of its period. We performed follow-up observations with the CHaracterising ExOPlanet Satellite (CHEOPS) to confirm the true period of HD 15906 c and improve the radius precision of the two planets. From TESS, CHEOPS, and additional ground-based photometry, we find that HD 15906 b has a radius of 2.24 ± 0.08 R⊕ and a period of 10.924709 ± 0.000032 d, whilst HD 15906 c has a radius of 2.93\^\+0.07\\-0.06\\ R⊕ and a period of 21.583298\^\+0.000052\\-0.000055\\ d. Assuming zero bond albedo and full day-night heat redistribution, the inner and outer planet have equilibrium temperatures of 668 ± 13 K and 532 ± 10 K, respectively. The HD 15906 system has become one of only six multiplanet systems with two warm (≲ 700 K) sub-Neptune sized planets transiting a bright star (G ≤ 10 mag). It is an excellent target for detailed characterization studies to constrain the composition of sub-Neptune planets and test theories of planet formation and evolution.

AB - We report the discovery of two warm sub-Neptunes transiting the bright (G = 9.5 mag) K-dwarf HD 15906 (TOI 461, TIC 4646810). This star was observed by the Transiting Exoplanet Survey Satellite (TESS) in sectors 4 and 31, revealing two small transiting planets. The inner planet, HD 15906 b, was detected with an unambiguous period but the outer planet, HD 15906 c, showed only two transits separated by ∼ 734 d, leading to 36 possible values of its period. We performed follow-up observations with the CHaracterising ExOPlanet Satellite (CHEOPS) to confirm the true period of HD 15906 c and improve the radius precision of the two planets. From TESS, CHEOPS, and additional ground-based photometry, we find that HD 15906 b has a radius of 2.24 ± 0.08 R⊕ and a period of 10.924709 ± 0.000032 d, whilst HD 15906 c has a radius of 2.93\^\+0.07\\-0.06\\ R⊕ and a period of 21.583298\^\+0.000052\\-0.000055\\ d. Assuming zero bond albedo and full day-night heat redistribution, the inner and outer planet have equilibrium temperatures of 668 ± 13 K and 532 ± 10 K, respectively. The HD 15906 system has become one of only six multiplanet systems with two warm (≲ 700 K) sub-Neptune sized planets transiting a bright star (G ≤ 10 mag). It is an excellent target for detailed characterization studies to constrain the composition of sub-Neptune planets and test theories of planet formation and evolution.

KW - techniques: photometric

KW - planets and satellites: detection

KW - planets and satellites: fundamental parameters

KW - stars: fundamental parameters

KW - stars: individual: HD 15906 (TOI 461, TIC 4646810)

U2 - 10.1093/mnras/stad1369

DO - 10.1093/mnras/stad1369

M3 - Article

SN - 0035-8711

VL - 523

SP - 3090

EP - 3118

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 2

ER -

TESS and CHEOPS discover two warm sub-Neptunes transiting the bright K-dwarf HD 15906

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