Secondary outflow driven by the protostar Ser-emb 15 in Serpens

We present the detection of a secondary outflow associated with a Class I source, Ser-emb 15, in the Serpens Molecular Cloud. We reveal two pairs of molecular outflows consisting of three lobes, namely primary and secondary outflows, using ALMA 12CO and SiO line observations at a resolution of 318 au. The secondary outflow is elongated approximately perpendicular to the axis of the primary outflow in the plane of the sky. We also identify two compact structures, Sources A and B, within an extended structure associated with Ser-emb 15 in the 1.3 mm continuum emission at a resolution of 40 au. The projected sizes of Sources A and B are 137 au and 60 au, respectively. Assuming a dust temperature of 20 K, we estimate the dust mass to be 0.0024 Msun for Source A and 0.00033 Msun for Source B. C18O line data imply the existence of rotational motion around the extended structure, however, cannot resolve rotational motion in Source A and/or B, due to insufficient angular and frequency resolutions. Therefore, we cannot conclude whether Ser-emb 15 is a single or binary system. Thus, either Source A or B could drive the secondary outflow. We discuss two scenarios to explain the driving mechanism of the primary and secondary outflows: the Ser-emb 15 system is (1) a binary system composed of Source A and B or (2) a single star system composed of only Source A. In either case, the system could be a suitable target for investigating the disk and/or binary formation processes in complicated environments. Detecting these outflows should contribute to understanding complex star-forming environments, which may be common in the star-formation processes.Comment: 21 pages, 10 figures, Accepted for publication in the Astrophysical Journa

Crescent-Shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA

We report on an Atacama Large Millimeter/submillimeter Array (ALMA) study of the Class I or II intermediate-mass protostar DK Cha in the Chamaeleon II region. The 12CO (J=2-1) images have an angular resolution of ~1'' (~250 au) and show high-velocity blueshifted (>70 km s-1) and redshifted (>50 km s-1) emissions which have 3000 au scale crescent-shaped structures around the protostellar disk traced in the 1.3mm continuum. Because the high-velocity components of the CO emission are associated with the protostar, we concluded that the emission traces the pole-on outflow. The blueshifted outflow lobe has a clear layered velocity gradient with a higher velocity component located on the inner side of the crescent shape, which can be explained by a model of an outflow with a higher velocity in the inner radii. Based on the directly driven outflow scenario, we estimated the driving radii from the observed outflow velocities and found that the driving region extends over two orders of magnitude. The 13CO emission traces a complex envelope structure with arc-like substructures with lengths of ~1000au. We identified the arc-like structures as streamers because they appear to be connected to a rotating infalling envelope. DK Cha is useful for understanding characteristics that are visible by looking at nearly face-on configurations of young protostellar systems, providing an alternative perspective for studying the star-formation process.Comment: Accepted for publication in ApJ. 12 pages, 5 figure

Ring Gap Structure around Class I Protostar WL 17

WL 17 is a Class I object and was considered to have a ring-hole structure. We analyzed the structure around WL 17 to investigate the detailed properties of WL 17. We used ALMA archival data, which have a higher angular resolution than previous observations. We investigated the WL 17 system with the 1.3 mm dust continuum and 12CO and C18O (J = 2-1) line emissions. The dust continuum emission showed a clear ring structure with inner and outer edges of ~11 and ~21 au, respectively. In addition, we detected an inner disk of < 5 au radius enclosing the central star within the ring, the first observation of this structure. Thus, WL 17 has a ring-gap structure, not a ring-hole structure. We did not detect any marked emission in either the gap or inner disk, indicating that there is no sign of a planet, circumplanetary disk, or binary companion. We identified the base of both blue-shifted and red-shifted outflows based on the 12CO emission, which is clearly associated with the disk around WL 17. The outflow mass ejection rate is ~3.6x10^-7 Msun yr-1 and the dynamical timescale is as short as ~ 10^4 yr. The C18O emission showed that an inhomogeneous infalling envelope, which can induce episodic mass accretion, is distributed in the region within ~1000 au from the central protostar. With these new findings, we can constrain the planet formation and dust growth scenarios in the accretion phase of star formation.Comment: 22 pages, 9 figures, Accepted for publication in the Astrophysical Journa

Children with Low Handgrip Strength: A Narrative Review of Possible Exercise Strategies to Improve Its Development

Background: Handgrip strength (HGS) is a predictor of health in both children and adults. Evidence suggests that without a possible strategy, children with low HGS may become adults with low HGS. However, little is known about what strategies are effective for children with low HGS to achieve a higher baseline level in adulthood. This narrative review aimed to investigate whether physical exercise interventions could improve HGS in children. Methods: The relevant databases/search engine was searched using keywords related to the main topics discussed throughout this review. Results: Our findings suggest that it may not be possible to improve HGS over that observed from normal development with physical education or traditional resistance-training programs. However, if the training program includes exercises that directly stimulate the forearm/hand muscle groups to grip, it may be possible to obtain changes in HGS that exceed the changes due to normal developmental growth. Conclusion: Although there are associations between HGS and markers of health, no research could be identified that examined whether increasing HGS would lead to an improvement in health. If an increase in HGS really does represent an improvement in long-term health, then gripping exercise may need to be included into physical activity programs during the growth/development phase

Cryptic species in a Vulnerable seabird : short-tailed albatross consists of two species

The occurrence of cryptic species within a threatened taxon is rare, but where they do occur, understanding species boundaries is essential for planning an effective conservation strategy. The short-tailed albatross Phoebastria albatrus is a Vulnerable seabird that mainly breeds on Torishima and the Senkaku Islands in the western North Pacific. Although it has been tacitly regarded as a single management unit with 2 breeding sites, the species is known to comprise 2 genetically separated populations (Senkaku-type and Torishima-type). However, morphological examination of birds from both populations has not been conducted owing to the difficulty in accessing the Senkaku Islands. In this study, we examined the morphological differences between immigrants from the Senkaku Islands to Torishima (Senkaku-type) and native birds on Torishima (Torishima-type) and found significant differences in morphological characteristics between the 2 bird types. In general, Torishima-type birds were larger than Senkaku-type birds, whereas Senkaku-type birds had relatively longer beaks. Based on the morphological differences found in this study as well as genetic and ecological differences revealed in previous studies, we believe that Senkaku- and Torishima-type birds should be classified as different cryptic species. To the best of our knowledge, this is the first case of cryptic species being identified in a threatened avian species

Secondary Outflow Driven by the Protostar Ser-emb 15 in Serpens

We present the detection of a secondary outflow associated with a Class I source, Ser-emb 15, in the Serpens Molecular Cloud. We reveal two pairs of molecular outflows consisting of three lobes, that is, primary and secondary outflows, using Atacama Large Millimeter/submillimeter Array  ^12 CO and SiO line observations at a resolution of ∼318 au. The secondary outflow is elongated approximately perpendicular to the axis of the primary outflow in the plane of the sky. We also identify two compact structures, Sources A and B, within an extended structure associated with Ser-emb 15 in the 1.3 mm continuum emission at a resolution of ∼40 au. The projected sizes of Sources A and B are 137 au and 60 au, respectively. Assuming a dust temperature of 20 K, we estimate the dust mass to be 2.4 × 10 ^−3 M _⊙ for Source A and 3.3 × 10 ^−4 M _⊙ for Source B. C ^18 O line data imply rotational motion around the extended structure, but we cannot resolve rotational motion in Source A and/or B because the angular and frequency resolutions are insufficient. Therefore, we cannot conclude whether Ser-emb 15 is a single or binary system. Thus, either Source A or Source B could drive the secondary outflow. We discuss two scenarios that might explain the driving mechanism of the primary and secondary outflows: the Ser-emb 15 system is (1) a binary system composed of Sources A and B, or (2) a single-star system composed of Source A alone. In either case, the system could be a suitable target for investigating the disk and/or binary formation processes in complicated environments. Detecting these outflows should contribute to understanding complex star-forming environments, which may be common in the star formation processes