J/AJ/152/195 HST and Magellan observations of Haumea system (Hastings+, 2016)
The short rotation period of Hi'iaka, Haumea's largest satellite.
Hastings D.M., Ragozzine D., Fabrycky D.C., Burkhart L.D., Fuentes C.,
Margot J.-L., Brown M.E., Holman M.
<Astron. J., 152, 195-195 (2016)>
=2016AJ....152..195H 2016AJ....152..195H (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Photometry, HST
Keywords: Kuiper belt objects: individual: Haumea -
planets and satellites: dynamical evolution and stability -
planets and satellites: individual: Hi'iaka - techniques: photometric
Abstract:
Hi'iaka is the larger outer satellite of the dwarf planet Haumea.
Using relative photometry from the Hubble Space Telescope and Magellan
and a phase dispersion minimization analysis, we have identified the
rotation period of Hi'iaka to be ∼9.8hr (double peaked). This is ∼120
times faster than its orbital period, creating new questions about the
formation of this system and possible tidal evolution. The rapid
rotation suggests that Hi'iaka could have a significant obliquity and
spin precession that could be visible in light curves within a few
years. We then turn to an investigation of what we learn about the
(currently unclear) formation of the Haumea system and family based on
this unexpectedly rapid rotation rate. We explore the importance of
the initial semimajor axis and rotation period in tidal evolution
theory and find that they strongly influence the time required to
despin to synchronous rotation, relevant to understanding a wide
variety of satellite and binary systems. We find that despinning tides
do not necessarily lead to synchronous spin periods for Hi'iaka, even
if it formed near the Roche limit. Therefore, the short rotation
period of Hi'iaka does not rule out significant tidal evolution.
Hi'iaka's spin period is also consistent with formation near its
current location and spin-up due to Haumea-centric impactors.
Description:
The Hubble Space Telescope (HST) observations of the Haumea system
comprised five HST orbits' worth of 100s exposures of the Wide Field
Planetary Camera 2 from 2009 February 4 (Program 11971) and 10 HST
orbits' worth of 44s exposures of the Wide Field Camera 3 from 2010
June 28 (Program 12243).
This system was also observed on the night of UT 2009 June 2 with the
Magellan Baade telescope at Las Campanas Observatory in Chile. We used
the Raymond and Beverly Sackler Magellan Instant Camera (MagIC).
Observations were taken from the beginning of the night until it was
unobservable, for a total of ∼5hr. We centered the system on one of
the four quadrants defined by the instrument's four amplifiers. The
seeing was constant during the observations and consistently close to
0.5'', smaller than Hi'iaka's separation of 1.4''. The SITe CCD
detector has a pixel scale of 0.069''/pixel. We set the exposure times
at 120s to avoid saturation and optimize readout time. The filter
selected was Johnson-Cousins R. Standard calibrations were taken at
the beginning and end of the night. The telescope guiding system
ensured that the pointing was constant to within an FWHM over the
course of the observations.
Table1 presents the relative normalized photometry inferred from our
observations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 27 420 Normalized relative photometry of Haumea
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See also:
B/astorb : Orbits of Minor Planets (Bowell+ 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d AJD HaumeA-centered Julian Date of observation
(after light travel time corrections) (1)
13- 18 F6.4 --- Flux [0.7679/1.0021] Normalized flux (2)
20- 25 F6.4 --- e_Flux [0.0056/0.0218] Error on Flux (2)
27 I1 --- n_Flux [1/3] Observing program (3)
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Note (1): Due to the different observation times, the Hi'iaka-observatory
distance changes significantly, introducing light-travel time variations.
Therefore, all times are converted to "HaumeA-centered Julian Date" (AJD),
a clock local to the Haumea system and therefore mutually self-consistent.
Note (2): Derived from relative photometry measurements. The photometry was
normalized by dividing each individual dataset by the maximum value of flux
from that dataset.
Note (3): Codes for the observing programs are defined as follows:
1 = HST Program 11971 on February 4, 2009;
2 = Magellan Observations on June 1, 2009;
3 = HST Program 12243 on June 28, 2010.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 31-Jan-2017