A likely exoplanet orbiting the oscillating K-giant<i>α</i>Arietis

Lee, B.-C.; Mkrtichian, D. E.; Han, Inwoo; Kim, K.-M.; Park, M.-G.

doi:10.1051/0004-6361/201016293

Cited by 23 publications

(25 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several stars with planetary-mass companions have already been discovered, mainly around red giants (Niedzielski et al 2007(Niedzielski et al , 2009aGettel et al 2012b,a). These findings supplement the slowly growing population of ∼50 planets currently known around evolved stars, discovered in such projects as the McDonald Observatory Planet Search , the Okayama Planet Search (Sato et al 2003), the Tautenburg Planet Search (Hatzes et al 2005), the Lick K-giant Survey (Frink et al 2002), the ESO FEROS planet search (Setiawan et al 2003a,b), the Retired A Stars and Their Companions (Johnson et al 2007), the CORALIE and HARPS search (Lovis & Mayor 2007), and the Boyunsen Planet Search (Lee et al 2011).…”

Section: Introductionmentioning

confidence: 90%

The Penn State-Toruń Centre for Astronomy Planet Search stars

Zieliński

Niedzielski

Wolszczan

et al. 2012

A&A

View full text Add to dashboard Cite

Aims. We present basic atmospheric parameters (T eff , log g, v t , and [Fe/H]) as well as luminosities, masses, radii, and absolute radial velocities for 348 stars, presumably giants, from the ∼1000 star sample observed within the Penn State-Toruń Centre for Astronomy Planet Search with the High Resolution Spectrograph of the 9.2 m Hobby-Eberly Telescope. The stellar parameters (luminosities, masses, radii) are key to properly interpreting newly discovered low-mass companions, while a systematic study of the complete sample will create a basis for future statistical considerations concerning the appearance of low-mass companions around evolved low-and intermediate-mass stars. Methods. The atmospheric parameters were derived using a strictly spectroscopic method based on the LTE analysis of equivalent widths of Fe I and Fe II lines. With existing photometric data and the Hipparcos parallaxes, we estimated stellar masses and ages via evolutionary tracks fitting. The stellar radii were calculated from either estimated masses and the spectroscopic log g or from the spectroscopic T eff and estimated luminosities. The absolute radial velocities were obtained by cross-correlating spectra with a numerical template. Results. We completed the spectroscopic analysis for 332 stars, 327 of which were found to be giants. A simplified analysis was applied to the remaining 16 stars, which had incomplete data. The results show that our sample is composed of stars with effective temperatures ranging from 4055 K to 6239 K, with log g between 1.39 and 4.78 (5 dwarfs were identified). The estimated luminosities are between log L/L = −1.0 and 3 and lead to masses ranging from 0.6 to 3.4 M . Only 63 stars with masses larger than 2 M were found. The radii of our stars range from 0.6 to 52 R with the vast majority between 9−11 R . The stars in our sample are generally less metal-abundant than the Sun with median [Fe/H] = −0.15. The estimated uncertainties in the atmospheric parameters were found to be comparable to those reached in other studies. However, due to lack of precise parallaxes, the stellar luminosities and, in turn, the masses are far less precise, within 0.2 M in best cases and 0.3 M on average.

show abstract

Section: Introductionmentioning

confidence: 90%

The Penn State-Toruń Centre for Astronomy Planet Search stars

Zieliński

Niedzielski

Wolszczan

et al. 2012

A&A

View full text Add to dashboard Cite

show abstract

“…The RV standard star τ Ceti shows an rms scatter of 6.7 m s −1 over the time span of our observations and demonstrates the long-term stability of the BOES (Lee et al 2011). …”

Section: Observations and Analysismentioning

confidence: 92%

“…We have reported two new exoplanets (Han et al 2010;Lee et al 2011) and confirmed an exoplanet ) and an oscillating star (Kim et al 2006).…”

Section: Observations and Analysismentioning

confidence: 99%

See 1 more Smart Citation

Detection of an exoplanet around the evolved K giant HD 66141

Lee

Mkrtichian

Han

et al. 2012

A&A

Self Cite

View full text Add to dashboard Cite

Aims. We have been carrying out a precise radial velocity (RV) survey for K giants to search for and study the origin of the lowamplitude and long-periodic RV variations. Methods. We present high-resolution RV measurements of the K2 giant HD 66141 from December 2003 to January 2011 using the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at the Bohyunsan Optical Astronomy Observatory (BOAO). Results. We find that the RV measurements for HD 66141 exhibit a periodic variation of 480.5 ± 0.5 days with a semi-amplitude of 146.2 ± 2.7 m s −1 . The Hipparcos photometry and bisector velocity span (BVS) do not show any obvious correlations with RV variations. We find indeed 706.4 ± 35.0 day variations in equivalent width (EW) measurements of H α line and 703.0 ± 39.4 day variations in a space-born measurements 1.25μ flux of HD 66141 measured during the COBE/DIRBE experiment. We reveal that a mean value of long-period variations is about 705 ± 53 days, whose origin is a rotation period of the star and variability that is caused by surface inhomogeneities. For the 480-day periods of RV variations an orbital motion is the most likely explanation. Assuming a stellar mass of 1.1 ± 0.1 M for HD 66141, we obtain a minimum mass for the planetary companion of 6.0 ± 0.3 M Jup with an orbital semi-major axis of 1.2 ± 0.1 AU and an eccentricity of 0.07 ± 0.03.

show abstract

“…Each estimated S/N at an I 2 region was about 200 with a typical exposure time ranging from 10 to 20 min. The long-term stability of the BOES was demonstrated by observing the RV standard star τ Ceti, which was constant with an rms scatter of 6.8 m s −1 over the time span of our observations (Lee et al 2011(Lee et al , 2012. We obtained 24 and 32 spectra each for HD 208527 and HD 220074, respectively, from September 2008 to June 2012.…”

Section: Observations and Reductionmentioning

confidence: 99%

Planetary companions orbiting M giants HD 208527 and HD 220074

Lee

Han

Park

2012

A&A

Self Cite

View full text Add to dashboard Cite

Aims. The purpose of the present study is to research the origin of planetary companions by using a precise radial velocity (RV) survey. Methods. The high-resolution spectroscopy of the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO) was used from September 2008 to June 2012. Results. We report the detection of two exoplanets in orbit around HD 208527 and HD 220074 exhibiting periodic variations in RV of 875.5 ± 5.8 and 672.1 ± 3.7 days. The RV variations are not apparently related to the surface inhomogeneities, and a Keplerian motion of the planetary companion is the most likely explanation. Assuming possible stellar masses of 1.6 ± 0.4 and 1.2 ± 0.3 M , we obtain the minimum masses for the exoplanets at 9.9 ± 1.7 and 11.1 ± 1.8 M Jup around HD 208527 and HD 220074 with orbital semi-major axes of 2.1 ± 0.2 and 1.6 ± 0.1 AU and eccentricities of 0.08 and 0.14, respectively. We also find that the previously known spectral classification of HD 208527 and HD 220074 was in error. Our new estimation of stellar parameters suggests that both HD 208527 and HD 220074 are M giants. Therefore, HD 208527 and HD 220074 are so far the first candidate M giants found to harbor a planetary companion.

show abstract

A likely exoplanet orbiting the oscillating K-giantαArietis

Cited by 23 publications

References 42 publications

The Penn State-Toruń Centre for Astronomy Planet Search stars

The Penn State-Toruń Centre for Astronomy Planet Search stars

Detection of an exoplanet around the evolved K giant HD 66141

Planetary companions orbiting M giants HD 208527 and HD 220074

Contact Info

Product

Resources

About