2013A&A...558A.140G


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.10CET16:39:24

2013A&A...558A.140G - Astronomy and Astrophysics, volume 558A, 140-140 (2013/10-1)

Extended envelopes around Galactic Cepheids. IV. T Monocerotis and X Sagittarii from mid-infrared interferometry with VLTI/MIDI.

GALLENNE A., MERAND A., KERVELLA P., CHESNEAU O., BREITFELDER J. and GIEREN W.

Abstract (from CDS):

We study the close environment of nearby Cepheids using high spatial resolution observations in the mid-infrared with the VLTI/MIDI instrument, a two-beam interferometric recombiner. We obtained spectra and visibilities for the classical Cepheids X Sgr and T Mon. We fitted the MIDI measurements, supplemented by B, V, J, H, K literature photometry, with the numerical transfer code DUSTY to determine the dust shell parameters. We used a typical dust composition for circumstellar environments. We detect an extended dusty environment in the spectra and visibilities for both stars, although T Mon might suffer from thermal background contamination. We attribute this to the presence of a circumstellar envelope (CSE) surrounding the Cepheids. This is optically thin for X Sgr (τ0.55µm=0.008), while it appears to be thicker for T Mon (τ0.55µm=0.15). They are located at about 15-20 stellar radii. Following our previous work, we derived a likely period-excess relation in the VISIR PAH1 filter, f8.6µm[%]=0.81(±0.04)P[day]. We argue that the impact of CSEs on the mid-IR period-luminosity (P-L) relation cannot be negligible because they can bias the Cepheid brightness by up to about 30%. For the K-band P-L relation, the CSE contribution seems to be lower (<5%), but the sample needs to be enlarged to firmly conclude that the impact of the CSEs is negligible in this band.

Abstract Copyright:

Journal keyword(s): techniques: high angular resolution - techniques: interferometric - circumstellar matter - stars: variables: Cepheids

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 V* T Mon cC* 06 25 12.9997562821 +07 05 08.561189768 8.24 7.20 5.98   4.996 G3Iabv+A0p 438 1
2 * 30 Gem PM* 06 43 59.2869703486 +13 13 40.818795627 6.82 5.65 4.49 3.63 3.03 K0+IIICa1 131 0
3 * 18 Mon SB* 06 47 51.6475157606 +02 24 43.840168370 6.62 5.58 4.47 3.68 3.13 K0+III 147 0
4 V* RS Pup cC* 08 13 04.2157137938 -34 34 42.691837063 8.89 8.00 6.70   5.453 F8Iab 311 1
5 * l Car cC* 09 45 14.8112246 -62 30 28.451894   4.33 3.40     G5Iab/b 281 1
6 V* X Sgr cC* 17 47 33.6241002643 -27 49 50.848981593 5.84 5.34 4.54   3.661 F7II 303 0
7 HD 168592 PM* 18 22 18.5735335091 -38 39 24.831468681   6.579 5.073     K4/5III 23 0
8 * lam Sgr PM* 18 27 58.2407185 -25 25 18.114589 4.75 3.85 2.81 2.06 1.50 K1IIIb 255 0

    Equat.    Gal    SGal    Ecl

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2019.12.10-16:39:24

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