J/ApJ/933/L21 g and i bands LCs of Bernhard-2 star (Zhu+, 2022)
Two candidate KH 15D-like systems from the Zwicky Transient Facility.
Zhu W., Bernhard K., Dai F., Fang M., Zanazzi J.J., Zang W., Dong S.,
Hambsch F.-J., Gan T., Wu Z., Poon M.
<Astrophys. J., 933, L21 (2022)>
=2022ApJ...933L..21Z 2022ApJ...933L..21Z
ADC_Keywords: Photometry, ugriz ; Stars, variable ; YSOs
Keywords: Circumstellar disks ; Variable stars
Abstract:
KH 15D contains a circumbinary disk that is tilted relative to the
orbital plane of the central binary. The precession of the disk and
the orbital motion of the binary together produce rich phenomena in
the photometric light curve. In this work, we present the discovery
and preliminary analysis of two objects that resemble the key features
of KH 15D from the Zwicky Transient Facility. These new objects,
Bernhard-1 and Bernhard-2, show large-amplitude ( >1.5 mag),
long-duration (more than tens of days), and periodic dimming events. A
one-sided screen model is developed to model the photometric behavior
of these objects, the physical interpretation of which is a tilted,
warped circumbinary disk occulting the inner binary. Changes in the
object light curves suggest potential precession periods over
timescales longer than 10yr. Additional photometric and spectroscopic
observations are encouraged to better understand the nature of these
interesting systems.
Description:
We attempted to obtain follow-up, high-cadence photometric
observations of Bernhard-2 when it was visible from the ground. A few
nights of observations were obtained from the 32inch telescope at the
Post Observatory, the 16inch telescope at the Remote Observatory
Atacama Desert Hambsch (2012JAVSO..40.1003H 2012JAVSO..40.1003H, ROAD), and the 1m
telescopes of the Las Cumbres Observatory Global Telescope Brown+
(2013PASP..125.1031B 2013PASP..125.1031B, LCOGT) in 2021 December, when the system was
exiting the egress. In early 2022, more systematic observations were
obtained on the 1m LCOGT telescopes and captured a broader range of
the egress region.
We observed Bernhard-2 with the High Resolution Echelle Spectrometer
on the 10m Keck I telescope (Keck/HIRES) at UT 07:42 on 2022 January
8, when the object was outside the occultation (section 3.3).
Objects:
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RA (ICRS) DE Designation(s)
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06 41 10.34 +09 28 33.4 KH 15D = V* V582 Mon
20 20 55.21 +38 13 23.1 Bernhard-1 = ZTF J202055.22+381323.1
07 14 45.39 -09 01 52.1 Bernhard-2 = ZTF J071445.39-090152.1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . this file
fig5.dat 61 692 LCOGT observations of Bernhard-2
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See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
VII/233 : 2MASS All-Sky Extended Source Cat. (XSC) (IPAC/UMass, 2003-2006)
J/AJ/140/2025 : KH 15D (V582 Mon) VI light curves (Herbst+, 2010)
J/ApJS/208/9 : Intrinsic colors and temp. of PMS stars (Pecaut+, 2013)
J/AJ/147/9 : VRIJHK light curves of V582 Mon (Windemuth+, 2014)
J/ApJ/788/41 : BVRI light curve of OGLE LMC-ECL-11893 (Dong+, 2014)
J/AJ/151/90 : Spitzer and VRIJHK phot. of V582 Mon (Arulanantham+, 2016)
J/AJ/153/188 : Spectro. of the foreground popul. in Orion A (Fang+, 2017)
J/AJ/155/47 : VRIJHK phot. of the T Tauri binary KH 15D (Aronow+, 2018)
J/ApJ/854/109 : Photometry & spectroscopy follow-up of MWC 882 (Zhou+, 2018)
J/ApJS/249/18 : The ZTF catalog of periodic variable stars (Chen+, 2020)
J/AJ/159/135 : VRIJHK light curves of V582 Mon (Garcia Soto+, 2020)
J/MNRAS/508/2370 : Revisiting the Cygnus OB associations (Quintana+, 2021)
Byte-by-byte Description of file: fig5.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d JD Julian date of observation
16- 33 F18.15 mag omag [16.47/21.48] Observed magnitude in Filter
35- 52 F18.16 mag e_omag [0.007/0.627] Uncertainty in omag
54- 55 A2 --- Filter Filter (1)
57- 61 A5 --- Obs Observatory (2)
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Note (1): Filter as follows:
CV = from the ROAD (404 occurrences)
SI = from the Post Observatory (68 occurrences)
SR = from the Post Observatory (59 occurrences)
g = from the LCOGT (76 occurrences)
i = from the LCOGT (85 occurrences)
Note (2): Observatory as follows:
ROAD = Remote Observatory Atacama Desert
Post = Post Observatory
LCOGT = Las Cumbres Observatory Global Telescope
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History:
From electronic version of the journal
(End) Prepared by [AAS], Katia van der Woerd [CDS] 13-Mar-2025