OGLE-2015-BLG-1609Lb: A sub-Jovian planet orbiting a low-mass stellar or brown dwarf host

Mróz, M. J.; Poleski, R.; Udalski, A.; Sumi, T.; Tsapras, Y.; Hundertmark, M.; Pietrukowicz, P.; Szymański, M. K.; Skowron, J.; Mróz, P.; Gromadzki, M.; Iwanek, P.; Kozłowski, S.; Ratajczak, M.; Rybicki, K. A.; Skowron, D. M.; Soszyński, I.; Ulaczyk, K.; Wrona, M.; Abe, F.; Bando, K.; Bennett, D. P.; Bhattacharya, A.; Bond, I. A.; Fukui, A.; Hamada, R.; Hamada, S.; Hamasaki, N.; Hirao, Y.; Ishitani Silva, S.; Itow, Y.; Koshimoto, N.; Matsubara, Y.; Miyazaki, S.; Muraki, Y.; Nagai, T.; Nunota, K.; Olmschenk, G.; Ranc, C.; Rattenbury, N. J.; Satoh, Y.; Suzuki, D.; Terry, S. K.; Tristram, P. J.; Vandorou, A.; Yama, H.; Street, R. A.; Bachelet, E.; Dominik, M.; Cassan, A.; Figuera Jaimes, R.; Horne, K.; Schmidt, R.; Snodgrass, C.; Wambsganss, J.; Steele, I. A.; Menzies, J.; Jørgensen, U. G.; Longa-Peña, P.; Peixinho, N.; Skottfelt, J.; Southworth, J.; Andersen, M. I.; Bozza, V.; Burgdorf, M. J.; D’Ago, G.; Hinse, T. C.; Kerins, E.; Korhonen, H.; Küffmeier, M.; Mancini, L.; Rabus, M.; Rahvar, S.

doi:10.1051/0004-6361/202453454

OGLE-2015-BLG-1609Lb: A sub-Jovian planet orbiting a low-mass stellar or brown dwarf host

Mróz, M. J.; Poleski, R.; Udalski, A.; Sumi, T.; Tsapras, Y.; Hundertmark, M.; Pietrukowicz, P.; Szymański, M. K.; Skowron, J.; Mróz, P.; Gromadzki, M.; Iwanek, P.; Kozłowski, S.; Ratajczak, M.; Rybicki, K. A.; Skowron, D. M.; Soszyński, I.; Ulaczyk, K.; Wrona, M.; Abe, F.; Bando, K.; Bennett, D. P.; Bhattacharya, A.; Bond, I. A.; Fukui, A.; Hamada, R.; Hamada, S.; Hamasaki, N.; Hirao, Y.; Ishitani Silva, S.; Itow, Y.; Koshimoto, N.; Matsubara, Y.; Miyazaki, S.; Muraki, Y.; Nagai, T.; Nunota, K.; Olmschenk, G.; Ranc, C.; Rattenbury, N. J.; Satoh, Y.; Suzuki, D.; Terry, S. K.; Tristram, P. J.; Vandorou, A.; Yama, H.; Street, R. A.; Bachelet, E.; Dominik, M.; Cassan, A.; Figuera Jaimes, R.; Horne, K.; Schmidt, R.; Snodgrass, C.; Wambsganss, J.; Steele, I. A.; Menzies, J.; Jørgensen, U. G.; Longa-Peña, P.; Peixinho, N.; Skottfelt, J.; Southworth, J.; Andersen, M. I.; Bozza, V.; Burgdorf, M. J.; D’Ago, G.; Hinse, T. C.; Kerins, E.; Korhonen, H.; Küffmeier, M.; Mancini, L.; Rabus, M.; Rahva...

Authors

M. J. Mróz

R. Poleski

A. Udalski

T. Sumi

Y. Tsapras

M. Hundertmark

P. Pietrukowicz

M. K. Szymański

J. Skowron

P. Mróz

M. Gromadzki

P. Iwanek

S. Kozłowski

M. Ratajczak

K. A. Rybicki

D. M. Skowron

I. Soszyński

K. Ulaczyk

M. Wrona

F. Abe

K. Bando

D. P. Bennett

A. Bhattacharya

I. A. Bond

A. Fukui

R. Hamada

S. Hamada

N. Hamasaki

Y. Hirao

S. Ishitani Silva

Y. Itow

N. Koshimoto

Y. Matsubara

S. Miyazaki

Y. Muraki

T. Nagai

K. Nunota

G. Olmschenk

C. Ranc

N. J. Rattenbury

Y. Satoh

D. Suzuki

S. K. Terry

P. J. Tristram

A. Vandorou

H. Yama

R. A. Street

E. Bachelet

M. Dominik

A. Cassan

R. Figuera Jaimes

K. Horne

R. Schmidt

C. Snodgrass

J. Wambsganss

I. A. Steele

J. Menzies

U. G. Jørgensen

P. Longa-Peña

N. Peixinho

J. Skottfelt

Dr John Taylor j.k.taylor@keele.ac.uk

M. I. Andersen

V. Bozza

M. J. Burgdorf

G. D’Ago

T. C. Hinse

E. Kerins

H. Korhonen

M. Küffmeier

L. Mancini

M. Rabus

S. Rahvar

Abstract

We present a comprehensive analysis of the planetary microlensing event OGLE-2015-BLG-1609. The planetary anomaly was detected by two survey telescopes, OGLE and MOA. Both surveys collected enough data over the planetary anomaly to enable an unambiguous planet detection. Such survey detections of planetary anomalies are needed to build a robust sample of planets, which could improve studies on the microlensing planetary occurrence rate by reducing biases and statistical uncertainties. In this work we examined different methods for modeling microlensing events using individual datasets. In particular, we incorporated a Galactic model prior to better constrain the poorly defined microlensing parallax. Ultimately, we fitted a comprehensive model to all available data, identifying three potential topologies, with two showing comparably high Bayesian evidence. Our analysis indicates that the host of the planet is either a brown dwarf, with a probability of 34%, or a low-mass stellar object (M dwarf), with a probability of 66%. The topology that provides the best fit to the data results in an extraordinary low host mass, Mh = 0.025+0.050-0.012M⊙, accompanied by an Earth-mass planet with Mc = 1.9+3.9-1.0M⊕.

Citation

Mróz, M. J., Poleski, R., Udalski, A., Sumi, T., Tsapras, Y., Hundertmark, M., Pietrukowicz, P., Szymański, M. K., Skowron, J., Mróz, P., Gromadzki, M., Iwanek, P., Kozłowski, S., Ratajczak, M., Rybicki, K. A., Skowron, D. M., Soszyński, I., Ulaczyk, K., Wrona, M., Abe, F., …Rahvar, S. (2025). OGLE-2015-BLG-1609Lb: A sub-Jovian planet orbiting a low-mass stellar or brown dwarf host. Astronomy & Astrophysics, 698, Article A126. https://doi.org/10.1051/0004-6361/202453454

Journal Article Type	Article
Acceptance Date	Apr 2, 2025
Online Publication Date	Jun 12, 2025
Publication Date	2025-06
Deposit Date	Aug 13, 2025
Journal	Astronomy & Astrophysics
Print ISSN	0004-6361
Electronic ISSN	1432-0746
Publisher	EDP Sciences
Peer Reviewed	Peer Reviewed
Volume	698
Article Number	A126
DOI	https://doi.org/10.1051/0004-6361/202453454
Public URL	https://keele-repository.worktribe.com/output/1366142
Publisher URL	https://www.aanda.org/articles/aa/full_html/2025/06/aa53454-24/aa53454-24.html