5 research outputs found
Discovery of Dust Emission Activity Emanating from Main-belt Asteroid 2015 FW412
We present the discovery of activity emanating from main-belt asteroid 2015
FW412, a finding stemming from the Citizen Science project Active Asteroids, a
NASA Partner program. We identified a pronounced tail originating from 2015
FW412 and oriented in the anti-motion direction in archival Blanco 4-m (Cerro
Tololo Inter-American Observatory, Chile) Dark Energy Camera (DECam) images
from UT 2015 April 13, 18, 19, 21 and 22. Activity occurred near perihelion,
consistent with the main-belt comets (MBCs), an active asteroid subset known
for sublimation-driven activity in the main asteroid belt; thus 2015 FW412 is a
candidate MBC. We did not detect activity on UT 2021 December 12 using the
Inamori-Magellan Areal Camera and Spectrograph (IMACS) on the 6.5 m Baade
telescope, when 2015 FW412 was near aphelion.Comment: 4 pages, 1 figur
HIP 67506 C: MagAO-X Confirmation of a New Low-Mass Stellar Companion to HIP 67506 A
We report the confirmation of HIP 67506 C, a new stellar companion to HIP
67506 A. We previously reported a candidate signal at 2/D (240~mas) in
L in MagAO/Clio imaging using the binary differential imaging
technique. Several additional indirect signals showed that the candidate signal
merited follow-up: significant astrometric acceleration in Gaia DR3,
Hipparcos-Gaia proper motion anomaly, and overluminosity compared to single
main sequence stars. We confirmed the companion, HIP 67506 C, at 0.1" with
MagAO-X in April, 2022. We characterized HIP 67506 C MagAO-X photometry and
astrometry, and estimated spectral type K7-M2; we also re-evaluated HIP 67506 A
in light of the close companion. Additionally we show that a previously
identified 9" companion, HIP 67506 B, is a much further distant unassociated
background star. We also discuss the utility of indirect signposts in
identifying small inner working angle candidate companions.Comment: 10 pages, 9 figures, 4 tables, accepted to MNRA
Implications for the Formation of (155140) 2005 UD from a New Convex Shape Model
(155140) 2005 UD has a similar orbit to (3200) Phaethon, an active asteroid in a highly eccentric orbit thought to be the source of the Geminid meteor shower. Evidence points to a genetic relationship between these two objects, but we have yet to fully understand how 2005 UD and Phaethon could have separated into this associated pair. Presented herein are new observations of 2005 UD from five observatories that were carried out during the 2018, 2019, and 2021 apparitions. We implemented light curve inversion using our new data, as well as dense and sparse archival data from epochs in 2005-2021, to better constrain the rotational period and derive a convex shape model of 2005 UD. We discuss two equally well-fitting pole solutions (lambda = 116.degrees 6, beta = -53.degrees 6) and (lambda = 300.degrees 3, beta = -55.degrees 4), the former largely in agreement with previous thermophysical analyses and the latter interesting due to its proximity to Phaethon's pole orientation. We also present a refined sidereal period of P (sid) = 5.234246 +/- 0.000097 hr. A search for surface color heterogeneity showed no significant rotational variation. An activity search using the deepest stacked image available of 2005 UD near aphelion did not reveal a coma or tail but allowed modeling of an upper limit of 0.04-0.37 kg s(-1) for dust production. We then leveraged our spin solutions to help limit the range of formation scenarios and the link to Phaethon in the context of nongravitational forces and timescales associated with the physical evolution of the system.Peer reviewe