J/MNRAS/483/3510 Polarization of stars with debris discs (Vandeportal+, 2019)
Polarization of stars with debris discs: comparing observations with models.
Vandeportal J., Bastien P., Simon A., Augereau J.-C., Storer E.
<Mon. Not. R. Astron. Soc., 483, 3510-3528 (2019)>
=2019MNRAS.483.3510V 2019MNRAS.483.3510V (SIMBAD/NED BibCode)
ADC_Keywords: Polarization ; Surveys ; Infrared
Keywords: polarization - scattering - surveys - circumstellar matter -
stars: individual (HD 165908, HD 7570, HR 8799, HD 115404, HD 137909)
Abstract:
The Herschel Space telescope carried out an unprecedented survey of
nearby stars for debris discs. The dust present in these debris discs
scatters and polarizes stellar light in the visible part of the
spectrum. We explore what can be learned with aperture polarimetry and
detailed radiative transfer modelling about stellar systems with
debris discs. We present a polarimetric survey, with measurements from
the literature, of candidate stars observed by DEBRIS and DUNES
Herschel surveys. We perform a statistical analysis of the
polarimetric data with the detection of far-infrared excess by
Herschel and Spitzer with a sample of 223 stars. Monte Carlo
simulations were performed to determine the effects of various model
parameters on the polarization level and find the mass required for
detection with current instruments. Eighteen stars were detected with
a polarization 0.01=<P~<0.1 per cent and ≥3σP, but only two
of them have a debris disc. No statistically significant difference is
found between the different groups of stars, with, without, and
unknown status for far-infrared excess, and presence of polarization.
The simulations show that the integrated polarization is rather small,
usually <0.01 per cent for typical masses detected by their
far-infrared excess for hot and most warm discs. Masses observed in
cold discs can produce polarization levels above 0.01 per cent since
there is usually more dust in them than in closer discs. We list five
factors which can explain the observed low-polarization detection
rate. Observations with high-precision polarimeters should lead to
additional constraints on models of unresolved debris discs.
Description:
We performed a coherent census of polarization due to nearby debris
discs for 109 stars. The stars were selected from the DEBRIS
(Rodriguez et al. 2015MNRAS.449.3160R 2015MNRAS.449.3160R, Cat. J/MNRAS/449/3160) and
DUNES (Eiroa et al. 2013A&A...555A..11E 2013A&A...555A..11E, Cat. J/A+A/555/A11) candidate
stars observed with Herschel. Combining with polarization measurements
from the literature for other candidate stars, we obtained a list of
223 stars with also information about the presence of debris discs
based on their mid- and far-IR excesses. Eighteen of them were
detected with a polarization P≥3σP, these stars are described
in table 1. The results for 205 stars with P<3σP are presented
in table A1.
The observations were made at the 1.6-m Ritchey-Chretien telescope of
the Mont-Megantic Observatory (OMM), based in Quebec, Canada. We
observed in three runs between 2009 December 1 and 2010 March 3. We
used an 8.18arcsec aperture; all multiple stars we observed were
integrated at the same time in the 8.18arcsec aperture. We used a
broadband red filter, RG645, which yields a bandpass centred at 766nm
with an full width at half-maximum (FWHM) of 241nm. Polarization was
measured with the Beauty and the Beast instrument which is a
two-channel photoelectric polarimeter. It uses a Wollaston prism as
analyser, a Pockels cell operated at 125Hz as modulator, and an
achromatic quarter-wave plate.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 81 18 All stars observed at OMM and from the Leroy
compilation with a polarization P≥3σP
tablea1.dat 87 205 Polarization data for all the stars observed at
OMM and from the Leroy compilation with a
polarization P<3σP
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- ID Star identification given by DEBRIS and SUNS
surveys (Phillips et al. 2010MNRAS.403.1089P 2010MNRAS.403.1089P,
Cat. J/MNRAS/403/1089) (G1)
6 A1 --- f_ID [*] Flag on ID (G2)
8- 16 A9 --- Name Name of the primary star (G3)
18- 20 I3 10-5 Pol Polarization
22- 23 I2 10-5 e_Pol Error on Pol
25- 29 F5.1 deg theta ? Equatorial polarization angle of the
polarization vector (G4)
31- 33 F3.1 deg e_theta ? Error on theta (G4)
35- 38 F4.1 --- PolR Pol to e_Pol ratio
40- 45 F6.3 pc Dist Distance
47- 51 F5.3 pc e_Dist Error on Dist
53- 56 F4.1 10-5/pc P/d Polarization to distance ratio
58- 60 F3.1 10-5/pc e_P/d Error on P/d
62 A1 --- FIR [YN?] Presence of a disc according to
far-infrared excess
(Gaspar et al. 2013ApJ...768...25G 2013ApJ...768...25G,
Cat. J/ApJ/768/25) (G5)
64- 74 A11 --- Obs Source of the data (G6)
76- 81 A6 --- Date Observation dates for OMM data
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- ID Star identification given by DEBRIS and SUNS
surveys (Phillips et al. 2010MNRAS.403.1089P 2010MNRAS.403.1089P,
Cat. J/MNRAS/403/1089) (G1)
6 A1 --- f_ID [*] Flag on ID (G2)
8- 18 A11 --- Name Name of the primary star (G3)
20- 22 I3 10-5 Pol Polarization
24- 26 I3 10-5 e_Pol Error on Pol
28- 32 F5.1 deg theta ? Equatorial polarization angle of the
polarization vector (G4)
34- 37 F4.1 deg e_theta ? Error on theta (G4)
39- 41 F3.1 --- PolR Pol to e_Pol ratio
43- 49 F7.3 pc Dist Distance
51- 55 F5.3 pc e_Dist Error on Dist
57 A1 --- FIR [YN?] Presence of a disc according to
far-infrared excess
(Gaspar et al. 2013ApJ...768...25G 2013ApJ...768...25G,
Cat. J/ApJ/768/25) (G5)
59- 72 A14 --- Obs Source of the data (G6)
74- 87 A14 --- Date Observation dates for OMM data
--------------------------------------------------------------------------------
General Notes:
Note (G1): The first letter represents its spectral class and the number is a
zero-padded running number increasing with distance in each
subsample.
These identifiers are referred to by the acronym UNS, standing for
Unbiased Nearby Stars, as in the original SUNS survey names.
Note (G2): Flag as follows:
* = Phillips et al. (2010MNRAS.403.1089P 2010MNRAS.403.1089P, Cat. J/MNRAS/403/1089) had two
entries for CCDM 15278+2906A and CCDM 15278+2906B as A065 in their
Table 7, and also their Table in the Vizier catalogue. Both of them
correspond to HD 137909 (β CrB). Its polarization was detected
by Leroy but not by Simon.
This led us to two different entries for this star, the detection by
Leroy in Table 1 and the non detection by Simon in Table A1. This has
no significant effect on our statistics below.
Note (G3): The choice of name is generally in the order of preference: HD, HIP,
GJ, LHS, NLTT, TYC, PPM, CCDM, other catalogue name, and 2MASS,
following Phillips et al. (2012yCat..74031089P,
Cat. J/MNRAS/403/1089)
Note (G4): When the uncertainty on the polarization angle is larger than ∼52deg,
its orientation is indefinite. Also, it is customary not to give the
polarization angle when the polarization is considered to be too
small to yield a reliable polarization angle.
Note (G5): Detection of FIR excess as follows:
Y = FIR excess detected
N = FIR excess not detected
? = no information or uncertain
Note (G6): Observers as follows:
SI = This paper (Vandeportal et al. 2019MNRAS.483.3510V 2019MNRAS.483.3510V)
AP = Appenzeller (1968ApJ...151..907A 1968ApJ...151..907A)
BE = Behr (1959VeGoe...7..200B 1959VeGoe...7..200B)
BM = Bhatt & Manoj (2000A&A...362..978B 2000A&A...362..978B)
HU = Huovelin et al. (1985A&A...152..357H 1985A&A...152..357H, 1988ApJ...329..882H 1988ApJ...329..882H,
1990A&A...231..588H 1990A&A...231..588H)
KO = Korhonen & Reiz (1986A&AS...64..487K 1986A&AS...64..487K)
KR = Krautter (1980A&AS...39..167K 1980A&AS...39..167K)
LE = Leroy (1993A&AS..101..551L 1993A&AS..101..551L, Cat. J/A+AS/101/551)
MA = Mathewson & Ford (1970MmRAS..74..139M 1970MmRAS..74..139M)
PI = Piirola (1977A&AS...30..213P 1977A&AS...30..213P)
SC = Schroder (1976A&AS...23..125S 1976A&AS...23..125S)
SE = Serkowski (1970ApJ...160.1083S 1970ApJ...160.1083S)
TI = Tinbergen (1982A&A...105...53T 1982A&A...105...53T)
WA = Walborn (1968PASP...80..162W 1968PASP...80..162W)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 27-Jul-2022