List of Y-dwarfs

This is a list of astronomical objects with the spectral type Y. They are a mix of brown dwarfs and planetary-mass objects. They are the coldest such objects in interstellar space and have a temperature around below 500 Kelvin (227°C; 440°F). Only a few are known due to their faint nature. The list is sorted after distance.

Table +List of Y-dwarfsNamespectral typeTeff (Kelvin)Mass estimate ()distance (light years)Year of discoveryJupiterY-class analog1251solar system known since ancient timesWISE J0855−0714Y4 (extrapolated)2763−107.432014Epsilon Indi AbY3 (estimated)2756.3111.8672018 (discovered) 2024 (imaging)WISE J1639−6847Y0pec3985−14 or 9−1715.452012WISE J0350−5658Y13553−8 or 7−1318.492012WISEPA J1541−2250Y14118−2018.92011WISE J2209+2711Y03558−19 or 520.172014WISEPC J1405+5534Y0.5 (pec?)3929−2120.62011WISEPA J0410+1502Y04518−2021.322011WISE J0825+2805Y0.53873−8 or 521.42015CWISE J1055+5443Y0 (pec)5004−6222023WISEPC J2056+1459Y048113−23 or 522.272011SMDET-1Y (estimate)<391<24.12026WISEPA J1738+2732Y04315−14, 3−9 or 11−2124.42011WISEA J2354+0240Y13478−14 or 2.525.02015WISENF J1936+0408Y0 (estimated)46028.62020WISE J0647−6232Y13945–13 or 4.629.62013WISE J0713−2917Y046413−2929.62012WISEPC J1217+1626 BY04608−2030.42012WISEA J1930−2059≥Y1 (estimated)37230.72020CWISEP J0402−2651≥Y1 (estimated)36731.22020WISEA J1141−3326Y04603–831.42014CWISEP J1446−2317Y13518.0 or 14.631.42020CWISEP J2256+4002≥Y1 (estimated)36732.02020WISEPA J1828+2650≥Y2462 or 480 + 340 binary3–832.52011WISE J0336−0143 AY0:4608.5–1832.72012WISE J0336−0143 BY2.5 (estimated)285–3055–11.532.72023WISEA J0830+2837≥Y1 (estimated)3454−1332.92020WISEU J0503−5648≥Y1 (estimated)36433.22020WISE J2220−3628Y04528–2034.92012CWISE J0925−4720Y0 (estimated)460~35.02021CWISER J0216+4230Y0 (estimated)460~35.22023WISEA J2243−1458Y0 (estimated)46037.42020WISE J1206+8401Y04726−14 or 12−2238.52015CWISEP J0238−1332≥Y1 (estimated)36738.62020CWISE J2351−7000Y0 (estimated)393292020WISE J0359−5401Y044312−22 or 1344.32012WISE J0734−7157Y04669−2044.52012WISE J0304−2705Y0 pec46544.62014CWISEP J2011−4812Y0 (estimated)4603.8462020CWISE J1811+6658early-Y (estimated)412472023CWISEP J1935−1546A≥Y1 (estimated)36712–39472019CWISEP J1935−1546B>Y1 (estimated)360–4207–24472025WISE J0535−7500Y1496 or 480 + 340 binary8−20 or 12+1847.52012CWISEP J0940+5233≥Y1 (estimated)4132.847.72020CWISEP J1047+5457Y139520.6 or 15.9 or 1–347.92020CWISEP J0321+6932Y0.5 (estimated)412482020WISEA J1257+7153≥Y1 (estimated)3824.748.22020CWISEP J0938+0634Y0 (estimated)46049.92020CWISEP J2230+2549≥Y1 (estimated)38952.42020CWISEP J2356−4814Y0.5 (estimated)4123.152.62020CWISEP J0634+5049Y0 (estimated)460532020WISEA J1534−1043esdY0–esdY2 (estimated)44753 ±42020WISEA J0302−5817Y0:460552018CWISE J1531−3306Y0 (estimated)460~55.42021CWISEP J0859+5349Y0 (estimated)46056.32020Ross 19 BsdY (estimated)460 ±7915−4056.892021WISE 0226-0211 BT9.5 to Y0 (estimated)511 ±7957.9201914 Herculis cY3 (estimated)2757.958.382021 (discovered) 2025 (imaging)CWISEP J2355+3804Y0 (estimate, might be T-dwarf)450602020WD 0806−661 BY03777−962.732011WISE J0146+4234 BY04118−20632015CWISE J2227+2604Y0 (estimated)460~65.22023CFBDSIR 1458+10 BY0 (estimated)3706–1575.342011CWISEP J1359-4352Y0 (estimated)47279.42020CWISEP J0156+3255sdY (estimated)1252020/2024JADES-GS-BD-5Y0-Y1~380457–6202024, shows proper motionJADES-GN-BD-8sdY (estimated)400–5021076-23482025PANO-GS-BD-18sdY (estimated)487–5111174–15002025Bullet-BD1Y (estimated)3507-1214022026 shows proper motionJADES-GS-BD-8sdY (estimated)404–5081500–30662024COSMOS-Web BD11sdY0 (estimated)75020202025Capotauro ≥Y1 (estimated)3422020–27402025 shows proper motionMoM-239450Y0450–5002283–27722026JADES-GS-BD-21sdY (estimated)340–5072414–58712025JADES-GN-BD-5sdY (estimated)398–5072707–39462025JADES-GN-BD-9sdY (estimated)441–5242740–48272025JADES-GN-BD-16sdY (estimated)375–5262838–56752025Bullet-BD2Y (estimated)41012-2228052026 shows proper motionCEERS-EGS-BD-6sdY (estimated)60035902024JADES-GS-BD-4sdY (estimated)483–5454175–50552024CEERS-EGS-BD-7sdY (estimated)65042402024COSMOS-Web BD16sdY0 (estimated)97546502025JADES-GN-BD-11sdY (estimated)463–5626817–101112025

JADES-GN-BD-1 and JADES-GN-BD-3 were included as Y-dwarf candidates, but were later found to be consistent with T-dwarfs. Multiple candidate companions found via infrared excess around white dwarfs and one companion (MEAD 62B) were found. Infrared excess candidates can however also be debris disks and a companion can be a background galaxy. Spectroscopy and common proper motion are needed for a confident detection. These are therefore not included, see List of exoplanets around white dwarfs for a list of candidates.

A large number of about 50 new candidate Y-dwarf were discovered with SPHEREx. These are only candidates and need confirmation.

Notes

References