J/ApJ/854/109 Photometry & spectroscopy follow-up of MWC 882 (Zhou+, 2018)
Occultations from an active accretion disk in a 72-day detached post-Algol
system detected by K2.
Zhou G., Rappaport S., Nelson L., Huang C.X., Senhadji A., Rodriguez J.E.,
Vanderburg A., Quinn S., Johnson C.I., Latham D.W., Torres G., Gary B.L.,
Tan T.G., Johnson M.C., Burt J., Kristiansen M.H., Jacobs T.L., LaCourse D.,
Schwengeler H.M., Terentev I., Bieryla A., Esquerdo G.A., Berlind P.,
Calkins M.L., Bento J., Cochran W.D., Karjalainen M., Hatzes A.P.,
Karjalainen R., Holden B., Butler R.P.
<Astrophys. J., 854, 109 (2018)>
=2018ApJ...854..109Z 2018ApJ...854..109Z
ADC_Keywords: Binaries, eclipsing; Photometry; Optical; Radial velocities
Keywords: accretion, accretion disks ; binaries: eclipsing ; stars: evolution
Abstract:
Disks in binary systems can cause exotic eclipsing events. MWC 882
(BD-224376, EPIC 225300403) is such a disk-eclipsing system identified
from observations during Campaign 11 of the K2 mission. We propose
that MWC 882 is a post-Algol system with a B7 donor star of mass
0.542±0.053M☉ in a 72-day orbit around an A0 accreting star of
mass 3.24±0.29M☉. The 59.9±6.2R☉ disk around the
accreting star occults the donor star once every orbit, inducing
19-day long, 7% deep eclipses identified by K2 and subsequently found
in pre-discovery All-Sky Automated Survey and All Sky Automated Survey
for Supernovae observations. We coordinated a campaign of photometric
and spectroscopic observations for MWC 882 to measure the dynamical
masses of the components and to monitor the system during eclipse. We
found the photometric eclipse to be gray to ∼1%. We found that the
primary star exhibits spectroscopic signatures of active accretion,
and we observed gas absorption features from the disk during eclipse.
We suggest that MWC 882 initially consisted of a ∼3.6M☉ donor
star transferring mass via Roche lobe overflow to a ∼2.1M☉
accretor in a ∼7-day initial orbit. Through angular momentum
conservation, the donor star is pushed outward during mass transfer to
its current orbit of 72 days. The observed state of the system
corresponds with the donor star having left the red giant branch
∼0.3Myr ago, terminating active mass transfer. The present disk is
expected to be short-lived (102yr) without an active feeding
mechanism, presenting a challenge to this model.
Description:
A total of 38 photometric occultations were recorded in multiple data
sets, including the K2 discovery light curves, pre-discovery data sets
from ground-based wide-field photometric surveys, and our
multiwavelength follow-up observations:
----------------------------------------------------------
Facility Dates Filter Number of
images
----------------------------------------------------------
ASAS 2001 Jan 31-2009 Oct 25 V 662
ASAS-SN 2015 Feb 16-2017 Jul 02 V 418
K2 2016 Sep 24-2016 Oct 18 Kp 1062
K2 2016 Oct 21-2016 Dec 07 Kp 2174
HAO 2017 Aug 30-2017 Sep 20 g' 1000
HAO 2017 Aug 30-2017 Sep 20 z' 870
PEST 2017 Sep 02-2017 Sep 12 B 79
PEST 2017 Sep 02-2017 Sep 12 V 79
PEST 2017 Sep 02-2017 Sep 12 I 83
----------------------------------------------------------
Ground-based photometric follow-up observations were obtained at the
Hereford Arizona Observatory (HAO), using a 0.36m Meade LX200 GPS
telescope with a Santa Barbara Instrument Group (SBIG) ST-10XME CCD
camera. We also obtained multiband follow-up observations of the 2017
September occultation with the Perth Exoplanet Survey Telescope (PEST)
located in Perth, Australia. PEST operates a fully automated 0.3m
Meade LX200 telescope, coupled with an SBIG ST-8XME CCD camera.
We obtained spectroscopic observations of MWC 882 with a series of
facilities over 2017 August and September.
A total of 11 observations were obtained using the Tillinghast
Reflector Echelle Spectrograph (TRES) on the 1.5m telescope at Fred
Lawrence Whipple Observatory, Mt. Hopkins, Arizona, USA.
We observed MWC 882 six times between 2017 August 28 and 2017
September 15 with the 2.7m Harlan J. Smith Telescope and its Robert G.
Tull Coude Spectrograph at McDonald Observatory, Mt. Locke, Texas, USA.
We also obtained an observation of MWC 882 using the 2.4m Automated
Planet Finder (APF) and the Levy spectrograph, located at Lick
observatory, Mt Hamilton, California, USA.
Objects:
---------------------------------------------------------------
RA (ICRS) DE Designation(s) (Period)
---------------------------------------------------------------
17 36 25.52 -22 46 17.9 MWC 882 = BD-22 4376 (P=72.42)
---------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 40 4453 Differential photometry for MWC 882
table5.dat 48 17 Relative radial velocities
--------------------------------------------------------------------------------
See also:
B/pollux : POLLUX database of synthetic stellar spectra (Palacios+ 2010-2015)
III/260 : General Catalogue of Ap and Am stars (Renson+ 2009)
II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)
J/A+A/463/671 : Rotational velocities of A-type stars. III. (Royer+, 2007)
J/ApJ/720/1118 : i-band photometry of HAT-P-16 (Buchhave+, 2010)
J/A+A/530/A146 : Spectral and UBV analysis of ε Aur (Chadima+ 2011)
J/A+A/537/A146 : Stellar models with rotation (0.8<M<120) (Ekstrom+, 2012)
J/ApJ/788/41 : BVRI light curve of OGLE LMC-ECL-11893 (Dong+, 2014)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 F15.7 d BJD [2451940.8/2458038.6] Barycentric Julian Date
of observation
17- 22 F6.4 mag Flux [0/1.2]? Differential Flux, magnitudes
24- 30 F7.4 mag e_Flux [0.0005/0.2]? Uncertainty in Flux
32- 37 A6 --- Inst Instrument (1)
39- 40 A2 --- Filt Filter (Kp, V, g', z', B or I)
--------------------------------------------------------------------------------
Note (1): Instrument as follows:
K2 = Campaign 11 of the K2 mission with the Kepler spacecraft
(Howell+ 2014PASP..126..398H 2014PASP..126..398H ; see also IV/34)
ASAS = Archival photometric observations from the All-Sky Automated Survey
(ASAS; see II/264). The survey has two units, one located in
Las Campanas, Chile, and the other in Haleakala, Maui.
ASASSN = ASAS-SN survey is monitoring the entire sky down to Vmag∼17
(Shappee+ 2014, J/ApJ/788/48 ; Kochanek+ 2017PASP..129j4502K 2017PASP..129j4502K).
HAO = the Hereford Arizona Observatory (HAO), using a 0.36m Meade LX200
GPS telescope with a Santa Barbara Instrument Group (SBIG) ST-10XME
CCD camera. The procedure for observations and reductions follows
that described in Rappaport+ (2016MNRAS.458.3904R 2016MNRAS.458.3904R ;
2018MNRAS.474..933R 2018MNRAS.474..933R).
PEST = the Perth Exoplanet Survey Telescope (PEST) located in Perth,
Australia.
See also the "Description" section above.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 F12.4 d BJD [2457960.7/2458021.7] Barycentric Julian Date
(TBD) of observation
14- 14 A1 --- Bl Blended RV flag (1)
16- 21 F6.2 km/s RV1 [-34.1/0]? Velocity of the accretor (2)
23- 26 F4.2 km/s e_RV1 [0/0.4]? Uncertainty in RV1
28- 34 F7.2 km/s RV2 [-108/54] Velocity of the donor (3)
36- 39 F4.2 km/s e_RV2 [0.5/2] Uncertainty in RV2 (4)
41- 48 A8 --- Inst Instrument (5)
--------------------------------------------------------------------------------
Note (1): Blended RV flag as follows:
d = Only velocities of the donor were measured; could not disentangle the
velocities of the accretor and donor from the line broadening kernels;
e = Only velocities of the donor were measured; the photospheric lines of
the accretor were contaminated by the disk absorption lines.
Note (2): Velocity of the accretor measured from the line broadening kernels.
Note (3): Velocity of the donor measured from the He I lines, which are present
only in the donor spectrum.
Note (4): A minimum uncertainty of 0.50 km/s is adopted to account for
systematic uncertainties.
Note (5): Instrument as follows:
TRES = the Tillinghast Reflector Echelle Spectrograph (TRES) on the 1.5m
telescope at Fred Lawrence Whipple Observatory. TRES is a
fiber-fed spectrograph with a spectral resolution of R∼44000 over
the wavelength range 3900-9100Å.
McDonald = the 2.7m Harlan J. Smith Telescope and its Robert G. Tull Coude
Spectrograph at McDonald Observatory (R=60000; 3570-10200Å).
APF = the 2.4m Automated Planet Finder (APF) coupled with a
high-resolution, slit-fed spectrograph that works at a typical
resolution of R∼110,000 (spectral range: 3750 to 7600Å).
See also the "Description" section above.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 12-Nov-2018