J/AJ/157/139 Inner Oort cloud survey observations: 2015 TG387 (Sheppard+, 2019)
A new high perihelion trans-Plutonian inner Oort cloud object: 2015 TG387.
Sheppard S.S., Trujillo C.A., Tholen D.J., Kaib N.
<Astron. J., 157, 139 (2019)>
=2019AJ....157..139S 2019AJ....157..139S (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Magnitudes
Keywords: comets: general - Kuiper belt: general -
minor planets, asteroids: general - Oort Cloud -
planets and satellites: individual (2015 TG387)
Abstract:
Inner Oort cloud objects (IOCs) are trans-Plutonian for their entire
orbits. They are beyond the strong gravitational influences of the known
planets, yet close enough to the Sun that outside forces are minimal.
Here we report the discovery of the third known IOC after Sedna and
2012 VP113, called 2015 TG387. This object has a perihelion of 65±1 au
and semimajor axis of 1170±70 au. The longitude of perihelion angle,
ω, for 2015 TG387 is between that of Sedna and 2012 VP113 and thus
similar to the main group of clustered extreme trans-Neptunian objects
(ETNOs), which may be shepherded into similar orbital angles by an unknown
massive distant planet called Planet X, or Planet Nine. The orbit of
2015 TG387 is stable over the age of the solar system from the known
planets and Galactic tide. When including outside stellar encounters over
4 Gyr, 2015 TG387's orbit is usually stable, but its dynamical evolution
depends on the stellar encounter scenarios used. Surprisingly, when
including a massive Planet X beyond a few hundred au on an eccentric orbit
that is antialigned in longitude of perihelion with most of the known
ETNOs, we find that 2015 TG387 is typically stable for Planet X orbits
that render the other ETNOs stable as well. Notably, 2015 TG387's argument
of perihelion is constrained, and its longitude of perihelion librates
about 180° from Planet X's longitude of perihelion, keeping 2015 TG387
antialigned with Planet X over the age of the solar system.
Description:
For discovery, our survey mainly uses the 8.2 m Subaru telescope (atop
Maunakea, Hawaii) in the Northern Hemisphere with the 1.5 deg2 Hyper
Suprime-Cam (HSC) and the 4 m Blanco telescope (at Cerro Tololo
Inter-American Observatory (CTIO)) in the Southern Hemisphere with the
2.7 deg2 Dark Energy Camera (DECam; Flaugher et al. 2015AJ....150..150F 2015AJ....150..150F).
Any objects found beyond about 50 au are recovered months and years later
with the 6.5 m Magellan and 4 m Discovery Channel Telescope (DCT) to obtain
the orbits of the objects. The r-band Subaru HSC images generally have
exposure times of about 300 s, but exposure times are increased or
decreased in order to reach about 25.5 mag in the r band, depending on the
observing conditions for each night. The DECam images use a very wide
broadband VR filter and are generally 420 s, with exposure times varied
depending on the observing conditions to reach near 25th magnitude in
the r band. Table 1 has about 1050 deg2 of new fields, giving the total
surveyed area to date about 2130 deg2 when including the fields from
Sheppard & Trujillo (2016, J/AJ/152/221).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 88 606 Further inner Oort cloud survey observations
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See also:
J/AJ/152/221 : New extreme trans-Neptunian objects (Sheppard+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "date" Date1 First UT observation date
12- 21 A10 "date" Date2 Last UT observation date
23- 30 A8 --- Tel Telescope (1)
32- 35 F4.1 h b_T [1.5/72] Approximate time between first & last
field images, lower value
37- 38 I2 h B_T [3/96]? Approximate time between first & last
field images, upper value
40- 43 F4.2 arcsec b_theta [0.45/1.3] Range of seeing for the night θ,
lower value
45- 47 F3.1 arcsec B_theta [0.6/1.6] Range of seeing for the night θ,
upper value
49- 52 F4.1 mag rlim [24/25.9] Limiting magnitude in r band (2)
54- 58 F5.1 deg2 Area [4.5/200] Area covered during the night
60- 69 A10 --- Field Field identifier (3)
71- 72 I2 h RAh Hour of Right Ascension (J2000)
74- 75 I2 min RAm Minute of Right Ascension (J2000)
77- 78 I2 s RAs Second of Right Ascension (J2000)
80 A1 --- DE- Sign of the Declination (J2000)
81- 82 I2 deg DEd Degree of Declination (J2000)
84- 85 I2 arcmin DEm Arcminute of Declination (J2000)
87- 88 I2 arcsec DEs Arcsecond of Declination (J2000)
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Note (1): Telescope as follows:
Subaru = HyperSuprimeCam on Subaru;
CTIO_4m = DECam on CTIO4m;
LBT = LB Camera on Large Binocular Telescope;
Magellan = IMACS on Magellan.
Note (2): Where we would have found at least 50% of the slow moving objects in
most of the fields.
Note (3): Field names were the names used at the telescope for each field and
are likely to be unimportant, but are included for full information.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 17-Jun-2019