Rotational periods of solar-mass young stars in Orion

Marilli, E.; Frasca, A.; Covino, E.; Alcalá, J. M.; Catalano, S.; Fernández, M.; Ferro, A. Arellano; Rubio-Herrera, E.; Spezzi, L.

doi:10.1051/0004-6361:20066458

Cited by 34 publications

(34 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This scenario has been supported through the years by different observational photometric studies which show that T-Tauri stars with disks (CTTS) have significantly longer periods than their disk-less counterparts (WTTS), i.e. they rotate at a small fraction (10-20%) of the break-up velocity (Attridge & Herbst 1992;Bouvier et al 1993;Edwards et al 1993;Choi & Herbst 1996;Marilli et al 2007). This indicates an efficient method for shedding AM, which is contrary to the expectation that these stars should spin close to break-up speed, having recently contracted from their natal clouds (Stassun et al 1999).…”

Section: Article Published By Edp Sciencesmentioning

confidence: 92%

Evidence of early disk-locking among low-mass members of the Orion Nebula Cluster

Biazzo

Melo

Pasquini

et al. 2009

A&A

View full text Add to dashboard Cite

Context. We present new high-resolution spectroscopic observations for 91 pre-main sequence stars in the Orion Nebular Cluster (ONC) with masses in the range 0.10−0.25 M carried out with the multi-fiber spectrograph flames attached to the UT2 at the Paranal Observatory. Aims. Our aim is to better understand the disk-locking scenario in very low-mass stars. Methods. We have derived radial velocities, projected rotational velocities, and full width at 10% of the Hα emission peak. Using published measurements of infrared excess (Δ(I C − K)), as disk tracer and equivalent width of the nead-infrared Ca ii line λ8542, mid-infrared difference [3.6]-[8.0] μm derived by Spitzer data, and 10% Hα width as diagnostic of the level of accretion, we looked for any correlation between projected angular rotational velocity divided by the radius (v sin i/R) and presence of disk and accretion. Results. For 4 low-mass stars, the cross-correlation function is clearly double-lined, indicating that the stars are SB2 systems. The distribution of rotation periods derived from our v sin i measurements is unimodal with a peak of a few days, in agreement with previous results for M < 0.25 M . The photometric periods were combined with our v sin i to derive the equatorial velocity and the distribution of rotational axes. Our sin i is lower than the one expected for a random distribution, as previously found. We find no evidence of a population of fast rotators close to the break-up velocity. A clear correlation between v sin i/R and Δ(I C − K) has been found. While a spread in the rotation rates is seen for stars with no circumstellar disk (Δ(I C − K) < 0.3), stars with a circumstellar disk (Δ(I C − K) > 0.3) show an abrupt drop in their rotation rates by a factor of ∼5. On the other hand, only a partial correlation between v sin i and accretion is observed when other indicators are used. The X-ray coronal activity level (log L X /L bol ) shows no dependence on v sin i/R, suggesting that all stars are in a saturated regime limit. The critical velocity is probably below our v sin i detection limit of 9 km s −1 . Conclusions. The ONC low-mass stars in our sample, close to the hydrogen burning limit, at present do not seem to be locked, but the clear correlation we find between rotation and infrared color excess suggests that they were locked once. In addition, the percentage of accretors seems to scale inversely to the stellar mass.

show abstract

Section: Article Published By Edp Sciencesmentioning

confidence: 92%

Evidence of early disk-locking among low-mass members of the Orion Nebula Cluster

Biazzo

Melo

Pasquini

et al. 2009

A&A

View full text Add to dashboard Cite

show abstract

“…They have well measured mass, radius and rotation frequency (Hartigan et al 1995;Bouvier et al 1997;Herbst & Mundt 2005;Marilli et al 2007). We suspected that one good such example of a faint jet in an evolved CTTS would be, among others, the RY Tau jet (Gómez de Castro & Verdugo 2001).…”

Section: Stellar Constraintsmentioning

confidence: 97%

Nonradial and nonpolytropic astrophysical outflows

Sauty

Méliani

Lima

et al. 2011

A&A

View full text Add to dashboard Cite

Context. A large sample of T Tauri stars exhibits optical jets, approximately half of which rotate slowly, only at ten per cent of their breakup velocity. The disk-locking mechanism has been shown to be inefficient to explain this observational fact. Aims. We show that low mass accreting T Tauri stars may have a strong stellar jet component that can effectively brake the star to the observed rotation speed. Methods. By means of a nonlinear separation of the variables in the full set of the MHD equations we construct semi-analytical solutions describing the dynamics and topology of the stellar component of the jet that emerges from the corona of the star. Results. We analyze two typical solutions with the same mass loss rate but different magnetic lever arms and jet radii. The first solution with a long lever arm and a wide jet radius effectively brakes the star and can be applied to the visible jets of T Tauri stars such as RY Tau. The second solution with a shorter lever arm and a very narrow jet radius may explain why similar stars, either weak line T Tauri stars (WTTS) or classical T Tauri stars (CTTS) do not all have visible jets. For instance, RY Tau itself seems to have different phases that probably depend on the activity of the star. Conclusions. First, stellar jets seem to be able to brake pre-main sequence stars with a low mass accreting rate. Second, jets may be visible only part time owing to changes in their boundary conditions. We also suggest a possible scenario for explaining the dichotomy between CTTS and WTTS, which rotate faster and do not have visible jets.

show abstract

“…Moreover, such a young scenario is at odds with: a) the distance from the galactic plane, which amounts to 166 ± 17 pc (given the spectroscopic distance of 725 ± 75 pc -see below -and galactic latitude of +12.92 • ); b) the relatively long rotation period of the star (P rot = 22.047 ± 0.121 days); c) the absence of high magnetic activity level (the peak-to-peak photometric variation is ∼0.5%); d) the lack of detectable Li  λ6708 Å absorption line in the co-added FIES spectrum. Short rotation period (P rot < ∼ 5 days), coupled with high magnetic activity and strong Li  λ6708 Å absorption line (EW Li > ∼ 300 mÅ), are usually regarded as youth indicators in PMS low-mass stars (see, e.g., Marilli et al 2007;Gandolfi et al 2008). …”

Section: Stellar Mass Radius and Agementioning

confidence: 99%

Kepler-423b: a half-Jupiter mass planet transiting a very old solar-like star

Parviainen

Deeg

Lanza

et al. 2015

A&A

View full text Add to dashboard Cite

We report the spectroscopic confirmation of the Kepler object of interest , a half-Jupiter mass planet transiting an old solar-like star every 2.7 days. Our analysis is the first to combine the full Kepler photometry (quarters 1−17) with high-precision radial velocity measurements taken with the FIES spectrograph at the Nordic Optical Telescope. We simultaneously modelled the photometric and spectroscopic data-sets using Bayesian approach coupled with Markov chain Monte Carlo sampling. We found that the Kepler pre-search data conditioned light curve of Kepler-423 exhibits quarter-to-quarter systematic variations of the transit depth, with a peak-to-peak amplitude of ∼4.3% and seasonal trends reoccurring every four quarters. We attributed these systematics to an incorrect assessment of the quarterly variation of the crowding metric. The host star Kepler-423 is a G4 dwarf with M = 0.85 ± 0.04 M , R = 0.95 ± 0.04 R , T eff = 5560 ± 80 K, [M/H] = −0.10 ± 0.05 dex, and with an age of 11 ± 2 Gyr. The planet Kepler-423b has a mass of M p = 0.595 ± 0.081 M Jup and a radius of R p = 1.192 ± 0.052 R Jup , yielding a planetary bulk density of ρ p = 0.459 ± 0.083 g cm −3 . The radius of Kepler-423b is consistent with both theoretical models for irradiated coreless giant planets and expectations based on empirical laws. The inclination of the stellar spin axis suggests that the system is aligned along the line of sight. We detected a tentative secondary eclipse of the planet at a 2σ confidence level (∆F ec = 14.2 ± 6.6 ppm) and found that the orbit might have a small non-zero eccentricity of 0.019 +0.028 −0.014 . With a Bond albedo of A B = 0.037 ± 0.019, Kepler-423b is one of the gas-giant planets with the lowest albedo known so far.

show abstract

Rotational periods of solar-mass young stars in Orion

Cited by 34 publications

References 33 publications

Evidence of early disk-locking among low-mass members of the Orion Nebula Cluster

Evidence of early disk-locking among low-mass members of the Orion Nebula Cluster

Nonradial and nonpolytropic astrophysical outflows

Kepler-423b: a half-Jupiter mass planet transiting a very old solar-like star

Contact Info

Product

Resources

About